Green Tea Niosomal Gel – An Approach For Protection Against Blue Light Induced Skin Damage

1.1 Topical drug delivery: -

Topical drug delivery system is traditional drug delivery system having a history of more than thousand years.in ancient Days ointment and salves are made from plant, animal and mineral extract. These preparations are delivered through a topical route for treatment of skin diseases. This method was employed by Chinese, Egyptians and Babylonians.¹ The skin acts as a barrier for the entry and exit of many chemicals, prevents moisture loss and controls body temperature to maintain homeostasis within the body. Topical preparations are useful in preventing gastric degradation of drug and avoids first pass metabolism.so, there is increase in bioavailability of the drug and these tropical preparations give its action directly at the site of action.²

Various Topical Formulations Available In Market Are Listed Below: -

• Semi -Solid preparations: -

Eg: - Gels, Paste, Creams, Ointments.

• Liquid Preparations: -

Eg: - Lotions, Solutions, Liniments.

• Solid Preparations: -

Eg: - Powders.

• Other Preparations: -

Eg: - Transdermal patches, Foams, Sprays, etc.³

BENEFITS OF TOPICAL DRUG DELIVERY SYSTEM: -

• Avoidance of First-Pass Metabolism.
• Targeted, Localized Therapy.
• Improved Patient Compliance.
• Reduced Systemic Side Effects.
• Patient-Friendly Formulations.
• Lower Dose and Enhanced Efficacy.
• Non-Invasive and Easily Reversible.
• Controlled or Sustained Release Possibilities.⁴

1.2 Anatomy and physiology of skin: -

The largest organ of the human body is skin, it covers about 15% of total adult body weight, it performs many important functions like protection against external physical, chemical and biological agents, it prevents excessive water loss from the body. The skin is composed of three main layers: -1) Epidermis, 2) Dermis and 3) Subcutaneous fascia .⁵ Epidermis is the outermost layer of the skin having different layers such as stratum spinosum, stratum granulosum, stratum lucidum, stratum basale.  Cells of epidermis includes keratinocytes, melanocytes, langerhans and marker cells. Dermis is a second layer of skin which is connected to epidermis by the basement membrane. The dermis is made up of two layers of connective tissue, the reticular and papillary, which blend together without obvious separation. The higher dermal layer, known as the papillary layer, is thinner and made up of loose connective tissue that comes into touch with the epidermis. The deeper, thicker, and less cellular layer is called the reticular layer. Collagen fiber bundles make up the dense connective tissue that makes up this layer. Hypodermis also known as Subcutaneous fascia, it is located beneath the dermis so it is called as hypodermis. It is the deepest layer of the skin, it consists of sensory neurons, blood vessels, hair follicle and adipose lobules.⁶

The skin structure and physiology play a crucial role in the delivery and permeation of drug via this route. The presence of hair follicles and pores plays a critical role in drug permeation.⁷ Stratum Corneum is layer of skin composing of 40% lipids, 40% proteins and only 20% water. So, this composition helps in permeation of liphophillic drug. This liphophillic character of drug is suitable for topical delivery of drugs. However hydrophilic drugs are difficult to pass through stratum corneum due to its less water content. Here the hair follicles and pores play role in the absorption of drugs.⁸

Fig 1.01: - Structure of Skin

 1.3 Skin Aging

Skin aging is a progressive biological process characterized by structural and functional deterioration.

It is classified into:

Intrinsic Aging

Occurs naturally due to:

• Genetics
• Hormonal alterations
• Cellular senescence
• Reduced collagen synthesis

Characteristics include:

• Fine wrinkles
• Thin epidermis
• Dry skin
• Reduced elasticity

Extrinsic Aging :

Major contributors Results from environmental factors.

include:

• Ultraviolet radiation
• Blue light
• Air pollution
• Cigarette smoke
• Poor nutrition
• Psychological stress

Extrinsic aging is largely mediated through oxidative stress.

1.4 Photoaging

Photoaging refers to premature aging caused by chronic exposure to environmental radiation.

Although ultraviolet radiation has traditionally been considered the principal cause of photoaging, increasing evidence suggests that prolonged exposure to visible blue light also contributes significantly to:

• Hyperpigmentation
• ROS generation
• DNA oxidation
• Collagen degradation
• Matrix metalloproteinase activation
• Wrinkle formation
• Skin barrier dysfunction

Unlike UVB, blue light penetrates deeper into the dermis, affecting fibroblasts and extracellular matrix proteins responsible for maintaining skin elasticity.

1.5 Blue Light: Sources and Characteristics

Visible light constitutes approximately 44% of the solar electromagnetic spectrum and ranges from 400 to 700 nm. Blue light, also referred to as High-Energy Visible (HEV) light, occupies the wavelength range of 400–500 nm. Owing to its relatively short wavelength and high photon energy, blue light possesses greater biological activity than other visible wavelengths and has become an important focus of dermatological and cosmetic research.

Historically, sunlight has been the major source of blue light. However, modern lifestyles have significantly increased exposure to artificial blue light through digital devices and LED-based illumination. Recent estimates suggest that people spend nearly 90% of their time indoors, where LED lighting and electronic screens have become the predominant sources of visible light exposure.

1.5.1 Sources of Blue Light

Natural sources include:

• Sunlight
• Clear daylight
• Reflected solar radiation

Artificial sources include:

• Smartphones
• Tablets
• Laptop computers
• Desktop monitors
• LED televisions
• LED bulbs
• Computer monitors
• Gaming devices
• Medical LEDs
• Cosmetic LED

1.5.2 Physical Properties of Blue Light

Table no.1 : Property of blue light

Because photon energy is inversely proportional to wavelength (Planck's equation), blue light possesses considerably greater energy than green, yellow, orange, or red light. This high energy enables interactions with endogenous chromophores and photosensitizers present within skin cells, initiating photochemical reactions that generate reactive oxygen species

1.5.3 Blue Light-Induced Skin Damage

Increasing evidence demonstrates that blue light induces numerous adverse biological effects on the skin. While ultraviolet radiation has traditionally been regarded as the principal environmental cause of photoaging, visible blue light has recently emerged as an independent contributor to oxidative skin damage.

Blue light penetrates more deeply than UVB radiation and reaches the dermis, where fibroblasts, collagen fibers, and elastin fibers reside. Consequently, prolonged exposure promotes extracellular matrix degradation and accelerates skin aging.

Major biological effects include:

1. ROS Generation

Blue light excites endogenous photosensitizers such as flavins, porphyrins, NADH, and lipofuscin. Excited photosensitizers transfer energy to molecular oxygen, generating ROS including:

• Superoxide anion (O?•?)
• Hydrogen peroxide (H?O?)
• Hydroxyl radicals (•OH)
• Singlet oxygen (¹O?)

ROS production represents the primary mechanism responsible for blue light-induced phototoxicity.

2. Oxidative Damage

Excess ROS attack cellular macromolecules:

• DNA
• Lipids
• Proteins
• Mitochondria
• Cell membranes

This oxidative damage disrupts normal cellular metabolism and promotes apoptosis.

3. DNA Damage

Experimental studies demonstrate that blue light induces:

• DNA strand breaks
• Oxidized nucleotides
• 8-OHdG formation
• Chromosomal instability

Persistent DNA damage accelerates cellular senescence and contributes to photoaging.

4. Inflammatory Response

Blue light stimulates inflammatory signaling pathways including:

• NF-κB
• MAPK
• AP-1
• TRPV1 activation

These pathways promote production of inflammatory mediators such as:

• TNF-α
• IL-1β
• IL-6
• COX-2

Inflammation subsequently enhances collagen degradation and impairs skin repair

5. Hyperpigmentation

Blue light activates melanocytes through:

• Opsin-3 receptor
• Calcium signaling
• MITF activation
• Increased tyrosinase expression

These events stimulate melanin synthesis, producing persistent pigmentation, particularly in individuals with darker skin phototypes.

6. Skin Barrier Dysfunction

Blue light reduces epidermal barrier integrity by:

• Increasing lipid peroxidation
• Disrupting keratinocyte differentiation
• Altering ceramide metabolism

Barrier impairment increases trans-epidermal water loss and skin sensitivity.

1.5.4 Mechanism of Blue Light-Induced Oxidative Stress

The mechanism of blue light-induced skin damage involves a cascade of molecular events.

Step 1

Blue light penetrates the epidermis and dermis.

Step 2

Endogenous chromophores absorb photons.

Step 3

Generation of ROS.

Step 4

Oxidative stress exceeds antioxidant defenses.

Step 5

Activation of:

NF-κB

MAPK

AP-1

TRPV1

Step 6

Production of inflammatory cytokines and matrix metalloproteinases.

Step 7

• Collagen degradation
• Elastin fragmentation
• DNA oxidation
• Hyperpigmentation
• Premature aging

This oxidative pathway provides the rationale for using antioxidant-rich botanical formulations to neutralize ROS before irreversible tissue damage occurs.

1.6 Gel: -

As per USP Gels are defined as a semi solid system containing either suspensions made up of small organic or inorganic molecules interpenetrated by a liquid. These are the preparation which are intended for application on the skin. Gels are generally considered to be more rigid because gels contain more covalent cross links, a higher density of physical bonds. ¹⁰ A gel consists of natural or synthetic polymers forming a three-dimensional matrix throughout a hydrophilic liquid or a dispersion medium. A gel is made up of two layers cross-linked, three-dimensional substance that contains a significant volume of liquid to create a stiff network which immobilizes the liquid continuous phase.

Ideal properties of topical gel:

• Gel should be clear and homogenous.
• Should be inert in nature.
• It should be stable, nonirritant.
• It should be non-sticky.
• It should have anti- microbial activity.

Advantages of Gel: -

• It can be used as controlled release formulation.
• They can be used to administer both polar and non-polar drugs.
• Easy to formulate as compared to other semi solid dosage form.
• They are biodegradable and biocompatible.
• They are washable and nontoxic in nature.
• Retention time is higher than other topical dosage forms.
• They provide excellent spread ability and cooling effect.

Disadvantages: -

• Some drug may degrade in gel formulation due to presence of polymer.
• Gelling agent may precipitate and result in salting out.
• Flocculation in some gel may produce an unstable gel.
• Solvent evaporation from the formulation may result in drying of the gel.
• The additives may induce irritation.
• The water content may increase the chances of microbial or fungal attack in gel.¹⁰

 1.6.1 Niosomal gel: -

Niosomal gels are semisolid systems where niosomes are embedded within a gel matrix, combining enhanced solubility, stability, and controlled release of therapeutic agents with easy topical application and prolonged residence time.¹¹ These systems improve penetration, bioavailability, and patient compliance while enabling sustained and targeted delivery.

Figure 1.02 : Structure of Niosomesz

1.7 Method of preparation of Noisome: -

1. Ether injection method

In this method cholesterol and non-ionic surfactant are dissolved in diethyl ether. This mixture is then injected through a 14 guage needle into an aqueous solution of drug maintained at 60°C. The ether solution is evaporated to room temperature giving single layered vesicles having particle size in the range of 50-1000nm. The advantage of this method includes control of size, which can be obtained by controlling the size of the needle whereas limited solubility of materials in ether and difficulty to remove ether from the final formulation are the disadvantages of this method.

Figure 1.03 : Ether Injection Method

2. Hand shaking method

In this method the vesicle forming agents, that is cholesterol and surfactant are dissolved in volatile organic solvent such as methanol, diethyl ether or chloroform in a round bottom flask. The solvent is then evaporated using rotary evaporator which leaves a thin film of solid mixture on the wall of the flask. This dried film of surfactant is hydrated using an aqueous solution of drug with gentle agitation giving milky niosomal dispersion. This is one of the most common methods forming multi lamellar niosomes.

Figure 1.04 : Hand Shaking Method

 3. Reverse phase evaporation method

In a mixture of organic solvent (ether and chloroform), equal ratios (1:1) of cholesterol and surfactant is dissolved. To the above phase an aqueous phase containing the drug is added giving a mixture of two phases. This phase is sonicated at 4-5°C to form a clear gel which is further sonicated after the addition of phosphate buffer saline. The organic phase is removed using rotary vacuum evaporator at 40°C and at reduced pressure. This results in a viscous suspension of noisome which is diluted with phosphate buffer saline at 60°C for 10 minutes to yield niosomes.

Figure 1.05 : Reverse Phase Evaporation Method

 4. Sonication 

An aqueous solution of drug in buffer is added to the mixture of surfactant and cholesterol. This mixture is added to a 10ml glass vial which is probe (titanium probe) sonicated for 3minutes at 60°C to yield niosomes. This method is also used to form SUV’s from MLV’s.

Figure 1.06 : Sonication Method

 5. Bubble method

This method has the advantage of preparing niosomes in one step without the use of organic solvent. In this method, all the vesicle forming components were dispersed in aqueous solution of drug and mixed for 15 sec using a high shear homogenizer. This homogenous dispersion was placed in a round bottom flask which had three necks. First neck was water cooled reflex. Second neck was thermometer to check the temperature and third neck was to provide the nitrogen supply. After homogenization the dispersion was immediately bubbled using a continuous stream of nitrogen gas bubbles giving niosomes, having mean particle size between 0.2 and 0.5 μm.

Figure 1.07 : Bubble Method

6. Micro fluidization method

 In this method two fluidized streams were made to interact at high velocities in micro channels within an interaction chamber. Due to the effect of high speed and energy small uniform uni-lamellar niosomes were formed. This was known as submerged jet principle which was found to have better reproducibility as compared to other methods.

Figure 1.08 : Microfluidization Method

 7. Multiple membrane extrusion

A mixture of surfactant, cholesterol and di-acetyl phosphate was dissolved in chloroform after which the solvent was evaporated using rotary evaporator leaving a thin film. This film was then hydrated using an aqueous solution of drug. The suspension formed was then extruded through polycarbonate membrane which was placed in series for up to 8 passages giving niosomes.

Figure 1.09 : Multiple Membrane Extrusion Metho

8. Transmembrane pH gradient technique

In this technique the surfactant and cholesterol placed in a round bottom flask and dissolved using an organic solvent such as chloroform. The solvent evaporated under reduced pressure thereby leaving a thin film on the walls of the flask. This film was hydrated by vortex mixing using citric acid having pH 4.0 which leads to the formation of multi lamellar vesicles. These vesicles were then frozen and thawed 3 times after which they were subjected to sonication thus forming niosomal suspension to which an aqueous solution of drug was further added. The pH of the aqueous drug sample was then increased to 7-7.5 using a base, usually disodium hydrogen phosphate so that a pH gradient was created across the niosomal membrane. In order to obtain niosomes this mixture was heated for 10 minutes at 60°C. The neutral pH gave mixture of protonated (membrane impermeable) and un-protonated (membrane permeable) forms of drug of which the un-protonated form of the drug crossed the niosome membrane and became protonated after entering the acidic medium thus getting trapped into the vesicle. This diffusion across the bilayer continued until the interior and exterior concentrations of drug attained equilibrium.

Figure 1.10 : Transmembrane pH gradient Method

9. Microfluidics Method

The microfluidics method is gaining interest as a novel production technology for nanoparticles, particularly niosomes. The idea of the microfluidics method originated in 1947 and the first use of microfluidic channels was in the 1990s. The adoption of microfluidic technology also occurred in the 1990s. The production of niosomes can be carried out using microfluidics devices. It consists of side channels alongside central channels. Both the organic and aqueous phases are pumped in different channels under pressure at a specific flow rate to an ice-filled interaction chamber. The niosomes are usually collected from the mixing channels using a glass vial. Uniform, small size, and cholesterol-niosomes are produced using this method. Based on Noelia et al. (2020), the niosomes produced by the microfluidics method are smaller in diameter compared to those produced by the thin film hydration method. Other advantages that can be observed when using the microfluidics method are as follows: the control of the input variables, minimal chemical usage, and the possibility of scaling up noisome production.

Figure 1.11 : Microfluidics Method

 1.8 Drug Profile

Figure 1.12 : EGCG Details

Epigallocatechin gallate (EGCG) is considered the principal active constituent.

Approximate concentration:

• 40–60% of total catechins.

1.8.1 Pharmacological Activities

Green tea possesses several pharmacological properties:

• Antioxidant
• Anti-inflammatory
• Anti-photoaging
• Anti-wrinkle
• Anti-melanogenic
• Anti-acne
• Antimicrobial
• Anti-carcinogenic
• UV protective
• Blue-light protective
• Free radical scavenging
• Collagen protective
• Anti-aging

1.8.2 Mechanism of Action

Green tea polyphenols act through multiple mechanisms:

• Scavenges reactive oxygen species (ROS)
• Inhibits lipid peroxidation
• Suppresses inflammatory cytokines
• Reduces oxidative stress
• Protects collagen and elastin
• Inhibits matrix metalloproteinases (MMP-1 and MMP-9)
• Activates endogenous antioxidant enzymes such as superoxide dismutase (SOD) and catalase.²⁹

1.8.3 Role in Anti-Blue Light Cosmetics

Green tea protects skin from blue light exposure by:

• Reducing intracellular ROS production
• Preventing oxidative DNA damage
• Protecting mitochondria
• Reducing inflammation
• Preventing premature aging
• Maintaining skin barrier integrity
• Decreasing melanin overproduction

1.8.4 Advantages in Niosomal Formulation

Green tea is suitable for niosomal delivery because:

• Catechins have poor skin penetration in conventional formulations.
• Niosomes improve encapsulation of polyphenols.
• They enhance stability against oxidation.
• They provide sustained drug release.
• They improve skin penetration and retention.
• They reduce degradation of EGCG.
• They increase bioavailability.

1.8.5 Therapeutic Uses

• Anti-aging creams
• Anti-wrinkle gels
• Anti-pigmentation products
• Acne formulations
• Skin-brightening cosmetics
• Wound healing formulations
• Antioxidant skincare
• Blue-light protection formulations

1.8.6 Storage

Store in:

• Well-closed, airtight container
• Cool, dry place
• Protected from direct sunlight and moisture
• Temperature below 25°C

1.8.7 Safety Profile

Green tea extract is generally considered safe for topical use.

Possible adverse effects:

• Mild skin irritation (rare)
• Allergic reactions in sensitive individuals
• Oxidation on prolonged exposure to air and light if not properly formulated.

1.8.8 EGCG DETAILS

The major active constituent of green tea, Epigallocatechin gallate (EGCG), has

Table no. 2 : Properties of EGCG

1.8.9 Mechanism of Action

EGCG exerts its pharmacological effects by:

• Neutralizing free radicals through hydrogen donation.
• Activating the Nrf2/ARE antioxidant pathway, increasing antioxidant enzymes such as superoxide dismutase (SOD), catalase, and glutathione peroxidase.
• Inhibiting the NF-κB signaling pathway, thereby reducing inflammation.
• Suppressing matrix metalloproteinases (MMPs), which protects collagen and elastin from degradation.
• Reducing lipid peroxidation and DNA damage caused by oxidative stress.
• Modulating signaling pathways such as MAPK, PI3K/Akt, and AMPK.

Relevance to Anti-Blue Light Niosomal Gel

For a green tea-loaded niosomal gel, EGCG:

• Protects skin cells from blue light-induced oxidative stress.
• Reduces intracellular ROS generation.
• Prevents premature skin aging and wrinkle formation.
• Helps maintain collagen integrity.
• Reduces hyperpigmentation by decreasing oxidative stress and inflammation.
• Enhances skin protection when delivered via niosomes due to improved stability and penetration.

1.7 Excipient profile: -

 A. Carbopol 934

Figure 1.13 : Carbopol 934 Details

1. Chemical Name

Carbopol® 934 (Carbomer 934)

2. Synonyms

• Carbomer 934
• Carbopol® 934
• Cross-linked polyacrylic acid

3. Chemical Class

• Synthetic high-molecular-weight polymer
• Cross-linked poly(acrylic acid)
• Hydrophilic gelling agent

4. Chemical Formula

Carbopol 934 is a polymer and does not have a fixed molecular or empirical formula.

Its repeating structural unit is commonly represented as:

(C?H?O?)?

5. Structural Formula

The repeating unit of Carbopol 934 is:

Figure 1.14 : Structure of Carbopol 934

It is a cross-linked polymer of acrylic acid using allyl ethers of sucrose or pentaerythritol as cross-linking agents.

6. Molecular Weight

• Very high molecular weight
• Approximately 3 × 10? to 4 × 10? Da (polymeric; not a single fixed value)

7. Appearance

• White, fluffy powder
• Hygroscopic

8. Odor

• Odourless

9. Solubility

• Dispersible in water
• Swells readily in water after neutralization
• Insoluble in ethanol, acetone, chloroform, and other organic solvents

10. pH

• 2.5–3.5 (0.5% aqueous dispersion)
• Forms clear gels after neutralization to approximately pH 6–7

11. Density

• Bulk density: approximately 0.20–0.40 g/cm³
• Tapped density: approximately 0.30–0.50 g/cm³

12. Melting Point

• Not applicable
• Decomposes upon heating; does not exhibit a true melting point.

13. Boiling Point

• Not applicable
• Being a high-molecular-weight polymer, it decomposes before boiling.

14. Viscosity

• Produces high-viscosity gels after neutralization.
• Typical viscosity (0.5% dispersion): 30,500–39,400 cP (depends on neutralization and testing conditions).

15. Function in Pharmaceutical Formulations

• Gelling agent
• Thickening agent
• Suspending agent
• Stabilizer
• Controlled-release matrix former
• Mucoadhesive polymer

16. Uses in Topical Formulations

• Topical gels
• Creams
• Lotions
• Ophthalmic preparations
• Cosmetic gels
• Niosomal gels
• Transdermal formulations

 17. Storage Conditions

• Store in a tightly closed container.
• Protect from moisture and excessive heat.
• Store at room temperature in a dry place.

B. Sodium Benzoate

Figure 1.15 : Sodium Benzoate Details

1. Chemical Name

Sodium Benzoate

2. Synonyms

• Benzoic acid sodium salt
• Sodium benzene carboxylate
• E211 (food additive)

3. Chemical Class

• Antimicrobial preservative
• Sodium salt of benzoic acid

4. Chemical Formula

 C?H?NaO?

5. Molecular Weight

144.11 g/mol

6. Chemical Structure

The structure consists of a benzene ring attached to a carboxylate group (COO?) with Na? as the counter ion.

Figure 1.16 : Structure of Sodium benzoate

7. CAS Number

532-32-1

8. Appearance

• White crystalline powder or granules

9. Odor

• Odourless or faint characteristic odour

10. Taste

?  Slightly sweet and astringent

11. Solubility

• Freely soluble in water
• Sparingly soluble in ethanol
• Practically insoluble in ether

12. pH

• 7.0–8.5 (1% aqueous solution)

13. Melting Point

• >300°C (decomposes)

14. Boiling Point

• Not applicable (decomposes before boiling)

15. Density

• 1.44 g/cm³ (approximately 20–25°C)

16. Function in Pharmaceutical/Cosmetic Formulations

• Antimicrobial preservative
• Prevents growth of bacteria, yeasts, and molds
• Extends shelf life of formulations

17. Mechanism of Action

Sodium benzoate is most effective in acidic formulations (pH < 5.5). It converts to benzoic acid, which penetrates microbial cells, disrupts enzyme activity, interferes with energy production, and inhibits microbial growth.

18. Typical Concentration

• Cosmetics: 0.1–0.5%
• Topical pharmaceutical formulations: 0.1–0.5%
• Maximum permitted concentration depends on regulatory requirements.

19. Compatibility

Compatible with:

• Carbopol 934/940
• Hydroxypropyl methylcellulose (HPMC)
• Glycerine
• Propylene glycol
• Herbal extracts
• Niosomal formulations

Less effective in alkaline formulations due to reduced conversion to benzoic acid.

20. Storage

• Store in a well-closed container.
• Protect from moisture.
• Keep in a cool, dry place away from direct sunlight.

21. Uses

• Topical gels
• Creams
• Lotions
• Oral pharmaceutical formulations
• Cosmetic products

C. Triethanolamine

Figure 1.17 : Triethanolamine Details

1. Chemical Name

Triethanolamine (TEA)

2. Synonyms

• TEA
• Tris(2-hydroxyethyl)amine
• 2,2′,2′′-Nitrilotriethanol

3. Chemical Class

• Organic amine
• pH-adjusting agent
• Neutralizing agent
• Emulsifying agent

4. Chemical Formula

C?H??NO?

5. Molecular Weight

149.19 g/mol

6. Chemical Structure

Triethanolamine consists of a tertiary amine attached to three hydroxyethyl (-CH?CH?OH) groups.

Structural formula:

Figure 1.18 : Structure of Triethanolamine

7. CAS Number

    102-71-6

8. Appearance

• Clear, colourless to pale yellow viscous liquid

9. Odor

• Mild ammonia-like odour

10. Solubility

• Miscible with water
• Miscible with ethanol
• Soluble in methanol and acetone

11. pH

• 10.0–11.5 (1% aqueous solution)

12. Melting Point

• 20–21°C

13. Boiling Point

• 335–336°C

14. Density

• 1.12–1.13 g/cm³ (at 20–25°C)

15. Refractive Index

?  1.482–1.485 (20°C)

16. Function in Pharmaceutical and Cosmetic Formulations

• Neutralizing agent
• pH adjuster
• Gelling agent activator (for Carbopol)
• Emulsifier
• Surfactant
• Buffering agent

17. Mechanism of Action

Triethanolamine neutralizes the acidic carboxyl groups of Carbopol 934/940, causing the polymer chains to uncoil and hydrate, thereby forming a clear, high-viscosity gel.

18. Typical Concentration

• 0.2–2% w/w in topical gels and creams

•  Added gradually until the desired pH (typically 5.5–6.5) is achieved

19. Compatibility

Compatible with:

• Carbopol 934
• Sodium Benzoate
• Glycerin
• Propylene glycol
• Herbal extracts
• Niosomal formulations

Avoid strong oxidizing agents.

20. Storage

• Store in a tightly closed container.
• Protect from moisture and direct sunlight.
• Store at room temperature.

21. Uses

• Topical gels
• Creams
• Lotions
• Emulsions
• Cosmetic products
• Pharmaceutical formulations

22. Role in Green Tea Niosomal Gel

In your green tea-loaded niosomal anti-blue light gel, triethanolamine is used to:

• Neutralize Carbopol 934.
• Adjust the gel pH to 5.5–6.5, which is suitable for skin application.
• Produce a smooth, transparent gel with appropriate viscosity.
• Improve the consistency and spreadability of the formulation.

D. Distilled water: -

Synonyms: Aqua, Hydrogen oxide

Chemical name: Water

Structural formula: (H?O)

Chemical structure:

Fig 1.19 : Structure of Water

Functional category: Solvent

Description: The chemical composition of portable water is variable; this portable water is then purified by distillation process in pharmaceutical practices. E.g. Water for injection.

Boiling point: 100 °C

Solubility: Miscible with most solvents.

Specific gravity: 0.9971

Surface tension: 71.97 mN/m

Vapour pressure: 3.17 kPa

Viscosity: 0.889 mPa·s

storage conditions: Water is stable in physical states.

Applications: Purified water is the most widely used excipients in pharmaceutical production operations. Purified water and water for injection are used for cleaning operation and in formulation of various products.

2. AIMS AND OBJECTIVES

2.1 Aim

The main aim of this work is to prepare and evaluate a niosomal gel containing Epigallocatechin Gallate for effective Blue Light Protection.

2.2 Objectives

The key objectives of the study are:

1. To procure, authenticate and prepare extract of Green Tea.
2. To perform phytochemical screening and standardization of prepared green tea extract
3. To formulate green tea niosomes using ether injection method.
4. To incorporate the optimized niosomal dispersion into a carbopol based topical gel.

2.3 Need of the Study

The increasing exposure to blue light from sunlight, smartphones, computers, and other digital devices has been associated with oxidative stress, premature skin aging, and hyperpigmentation. Although green tea (Camellia sinensis) extract possesses potent antioxidant and photoprotective properties due to its catechin content, its topical application is limited by poor stability and low skin penetration. Incorporation of green tea extract into niosomes can enhance its stability, improve skin permeation, and provide controlled release of the active constituents. Therefore, the present study aims to develop and evaluate a green tea extract-loaded niosomal gel as a novel topical formulation for protection against blue light-induced skin damage.

3.0 METHODOLOGY

The chemicals that were used are AR/LR grade or the best possible grade available were used as supplied by the manufacturer without further purification or investigation.

Table no 3: List of chemicals

Table no 4: List of equipment’s

3.1 PREPARATION OF GREEN TEA EXTRACT

1. Pulvarize into coarse powder.
2. Pass through sieve no.40.
3. Weigh 100g of powder
4. Extract using 70% ethanol by maceration for 48hr.[or oxhlet extraction can be done]
5. Filter through whatman no.1 filter paper.
6. Concentrate under reduced pressure using rotary evaporator below 45*C.
7. Dry in a vacuum desicator or autoclave.
8. Store in an amber glass container at 4*C

3.2 PRE-FORMULATION STUDIES OF GREEN TEA CATECHIN EXTRACT

1. Authentication of Crude Drug

The authentication is based on supplier information provided with the green tea material.

2. Organoleptic Evaluation

The green tea catechin extract was evaluated for its physical characteristics, including colour, odour, appearance, and texture. Organoleptic evaluation provides preliminary information regarding the quality, identity, and acceptability of the extract before formulation.

3. Solubility Study

The solubility of green tea catechin extract was determined in different solvents to identify a suitable solvent system for formulation development. Solubility influences drug loading, entrapment efficiency, and release characteristics of the final dosage form.

4. pH Determination

The pH of the green tea catechin extract solution was measured using a calibrated digital pH meter. Determination of pH is important to ensure compatibility of the extract with excipients and to maintain skin-friendly characteristics in the topical formulation.

5. Moisture Content

The moisture content of the extract was determined by the loss-on-drying method. Moisture determination is essential to evaluate the stability and storage characteristics of the extract, as excess moisture may lead to degradation or microbial growth

6. Determination of λmax by UV Colorimeter

The maximum absorption wavelength (λmax) of the green tea catechin extract was determined using a UV–Visible spectrophotometer. The λmax is used for the quantitative estimation of the extract during drug content determination, entrapment efficiency, and in vitro release studies.

7. Ferric Chloride Test

The ferric chloride test was performed as a qualitative phytochemical test to confirm the presence of phenolic compounds in the green tea catechin extract. Catechins, particularly epigallocatechin gallate (EGCG), contain phenolic hydroxyl groups that react with ferric chloride to produce a characteristic greenish-blue or blue-black colour.8. Partition Coefficient

Transfer 10 mL of green tea extract into a separating funnel and add 10 mL benzene. Shake gently with frequent venting and allow the layers to separate completely. Collect the aqueous and benzene layers separately. Take 10 mL of the aqueous layer in a conical flask, add 20–30 mL distilled water and 2–3 drops of phenolphthalein. Titrate with standardized 0.1 N NaOH until a persistent pale-pink endpoint is obtained. Record the titre value and repeat the titration to obtain concordant readings. Calculate the concentration of the aqueous phase using N?V? = N?V?. Determine the concentration in the benzene phase using a suitable validated estimation method.

8. Partition Coefficient

Take 10 mL of green tea extract and 10 mL of benzene in a separating funnel. Shake gently and allow the layers to separate. Collect the aqueous and benzene layers separately. Take a measured aliquot of the aqueous layer, add distilled water and phenolphthalein, and titrate with standardized 0.1 N NaOH until a persistent pale-pink endpoint is obtained. Determine the concentration of the extract in both layers and calculate the partition coefficient.

3.3 PREPARATION OF GREEN TEA CATECHIN EXTRACT NIOSOME

Table no. 5: Formulation Chart of Niosome

Ether injection method

1. Dissolve:

• Span 60
• Stearic acid
• Green tea extract
• Dissolve in Diethylether

2. Heat the aqueous phase (phosphate buffer) to about 60–65°C (or above the phase transition temperature of the surfactant used).
3. Inject the organic phase slowly into the hot aqueous phase using a syringe.
4. The ether evaporates immediately due to the high temperature.
5. As the solvent evaporates, niosomal vesicles form spontaneously.
6. Allow any remaining ether to evaporate completely.
7. If needed, sonicate the dispersion to reduce particle size.
8. Do the centrifugation to get concentrated niosome dispersion.

3.4 EVALUATION OF NIOSOMES: -

1. Drug Entrapment efficiency ³⁰                                                                                                            Entrapment efficiency of niosomes was determined by exhaustive dialysis method. The measured quantity of niosomal suspension was taken into a dialysis tube to which osmosis cellulose membrane was securely attached on one side.⁵⁷ The dialysis tube was suspended in 100ml phosphate buffer (pH 7.4), which was stirred on a magnetic stirrer. The unentrapped drug was separated from the niosomal suspension into the medium through osmosis cellulose membrane. At every hour entire medium (100ml) was replaced with fresh medium (for about 4-5h) till the absorbance reached a constant reading indicating no drug is available in unentrapped form.⁵⁷ The niosomal suspension in the dialysis tube was further lysed with propane-1-ol and estimated the entrapped drug by UV spectrophotometric method at 274nm. The entrapment efficiency was calculated using following equation. Amount of entrapped drug.

% Entrapment Efficiency = Total amount of Drug -Free amount of Drug     _X100                                                                                                                                                                     Total amount of Drug

2. Zeta potential ²⁸

The zeta potential is an essential parameter in the characterization of the colloidal stability of systems such as niosomes. It represents the difference in electrical potential between the particle surface and the diffuse layer of ions surrounding it, known as the electric dual layer. This potential, expressed in millivolts, indicates the degree of electrostatic repulsion between particles with similar surface charges. High values (positive or negative) suggest greater stability, as they decrease the probability of niosome aggregation or flocculation, which is crucial for maintaining their structural integrity and functionality in pharmaceutical or biomedical applications.

3. Scanning Electron Microscopy (SEM)²⁷

Used to study surface morphology.

Shows external surface and vesicle shape.

Samples are dried and coated with gold before imaging.

3.5 Preparation of Green Tea Catechin Extract Niosomal gel:

Table no.6 : Formulation Chart of Niosomal Gel

 Disperse 0.5 g Carbopol 934 in approximately 50 mL distilled water with continuous stirring using magnetic stirrer.

1. Allow the dispersion to hydrate for 12–24 hours to obtain a lump-free gel base.
2. Add 2ml glycerin and 5ml propylene glycol, and stir until homogeneous.
3. Dissolve 0.2g sodium benzoate in a small quantity of distilled water and add it to the gel base.
4. Add the optimized green tea-loaded niosomal suspension slowly with gentle stirring to avoid rupture of vesicles.
5. Adjust the pH to 5.5–6.5 by adding triethanolamine dropwise while stirring.
6. Continue stirring until a smooth, homogeneous gel is obtained.
7. Transfer the gel into clean, airtight aluminum tubes or amber glass containers.

Figure 3.01: Preparation of Niosomal Gel

3.6 EVALUATION OF NIOSOMAL GEL: -

1. Visual inspection
2. PH determination
3. Viscosity
4. Spreadability
5. Skin Irritation Test

 Visual inspection ³⁸

Green tea niosomal gel underwent visual inspection to assess their uniformity, texture, absence of phase separation, and any signs of aggregation.

PH determination ³⁹

A specific quantity of gel, measured in grammes, was precisely weighed and subsequently dispersed in 25 ml of distilled water. pH of dispersion was determined using a digital pH meter.

 Viscosity²⁸

The viscosity of prepared gel was measured using Brookfield viscometer at different RPM viscosity was measured and noted. The measurement was made over the whole range of speed settings from 5-100 rpm with 10 seconds between two successive speeds.

 Spreadability²⁸

The Spreadability of the gel formulation was determined by using sliding plate apparatus and by measuring the diameter of 1 gm of gel between horizontal plates after 1 minute. The standardized weight tied on the upper plate was 20 gm. An excess of gel is placed between two glass slides and a 1000 gm weight is placed on them for 5 minutes, to compress the sample to a uniform thickness. The bottom slide is anchored to the apparatus and weights are placed in the pan. The time in seconds needed to separate the two slides is taken as a measure of spreadability. A shorter time interval indicates better spreadability. Spreadability was determined by using the following formula.

Where,

M = weight tied to the upper slide.

 L = length of the glass slide.

 T = Time taken to separate two slides (sec).

Skin Irritation Test

Apply the gel on the skin and leave for some time to check the irritation or inflammation.

4.0 RESULTS

4.1 PREFORMULATION STUDY

Authentication of Crude Drug

The green tea was procured from Naturgized India INC. Order ID: ORD31281277677

Organoleptic Evaluation

Table no.7 : Organoleptic Evaluation

Solubility Study

Table no. 8 : Solubility Study

pH Determination

Prepare a 1% w/v solution of the extract in distilled water and measure the pH.

pH = 5.99

Figure 4.01 : pH Determination

Moisture Content

Weight of empty dish (W?) = 37.47 g

Weight of sample + petri dish (before drying) (W?) = 42.45 g

Weight of sample + petri dish (after drying) (W?) = 42.25 g

Moisture Content (%) = [(42.45 − 42.25) / (42.45 − 37.47)] × 100

 = (0.20 / 4.98) × 100

 = 4.01%

Determination of λmax by Colorimeter

Dissolve the sample in methanol.

Scan between 200–400 nm.

Characteristic absorption maximum (λ max): approximately 274–280 nm.

Observed (λ max): 279 nm.

Figure 4.02 : Colorimetry

Ferric Chloride Test (Qualitative Test for Polyphenols)

Add a few drops of 1% FeCl? solution to the sample.

Observation: Development of a dark green to blue-black colour, indicating the presence of phenolic compounds (including catechins such as EGCG).

Figure 4.03 : Ferric Chloride Test

Partition Coefficient

The Partition Coefficient of EGCG is estimated to be 0.739.

Table no.9 : Partition Coefficient

4.2 EVALUATION OF GREEN TEA CATECHIN NIOSOME DISPERSION

Physical Inspection

Table no.10 : Physical Evaluation of Niosome

Figure 4.04 : Physical Inspection of Niosome

Morphological Study

The noisomes were 200-300nm, spherical in shape with a closed vesicular structure and narrow size distribution.

Figure 4.05 : Scanning Electron Microscopy image of the EGCG noisome

Zeta Potential

The zeta potential of the EGCG noisome was found to be -39.9 mV. The zeta potential distribution showed a single predominant peak at -40.0 mV.

Figure 4.06 : Zeta potential of EGCG Niosome

Entrapment Efficiency

Table no.11 : Entrapment Efficiency

4.3 EVALUATION OF GREEN TEA EXTRACT NIOSOMAL GEL

Visual inspection

Table no.12 : Visual Inspection of Niosomal Gel

Figure 4.07 : Visual Inspection of Niosomal Gel

pH determination

Table no.13: pH Determination of Niosomal Gel

Figure 4.08 : pH Determination of Niosomal Gel

 Viscosity

Table no.14 : Viscosity Determination

Figure 4.09 : Viscosity Determination

Spreadability

Table no.15 : Spreadability Determination

Skin Irritation Test

Table no.16 : Skin Irritation Test