Innovative Nanocarrier System in Cosmeceutical: A Comprehensive Review on Anti-Ageing and Hair Care Applications.

COSMETICS:

Cosmetic preparations, esteemed and utilized by individuals of all genders since antiquity, primarily serve rejuvenate and aesthetic enhancement purposes. These formulations are generally applied topically and may consist of single constituents or complex blends of ingredients sourced from natural or synthetic origins.^[1] Such products are employed in the management of diverse dermatological and trichological conditions, including hair damage, wrinkle formation, photoaging, xerosis (dry skin), hypopigmentation, and hyperpigmentation. They exert quantifiable restorative and protective effects on the skin and hair, thereby functioning as an intermediary domain bridging conventional pharmaceuticals and cosmetic formulations ^[1].   They contain biologically active substances that provide therapeutic and cosmetic benefits to the skin.  The name "cosmetics" is derived from the term "COSMETIKOS," which signifies the ability to adorn. They include a wide range of formulations such as creams, lotions, lipsticks, perfumes, nail polishes, eye and facial makeup, hair colours, and deodorants ^[2]. In ancient societies like Egypt, Greece, Rome, and India, natural resources like oils, clays, and plant extracts were utilized for both religious and cosmetic purposes. With the merging of chemistry, dermatology, and modern technology, cosmetic science has developed over time to provide products that are both visually beautiful and advantageous for skin health ^[2].

Figure 1: cosmetics

As a result, cosmetics are now more than just beauty enhancers; they are an important part of self-expression, personal care, and cleanliness, reflecting both scientific breakthroughs and cultural values ^[3].The effectiveness of cosmetics is dependent on both the active chemicals and the technology used in their preparation. Creams, lotions, and gels often contain an active ingredient to target the location and substance that forms the base, vehicle, and presentation of the product.

Nanotechnology:

By integrating nanostructures and nanophases across diverse scientific disciplines particularly within nanomedicine and nano-based drug delivery systems nanotechnology has effectively bridged the interface between the physical and biological sciences. Nanomaterials, defined as substances with dimensions ranging from 1 to 1000 nm, significantly influence the advancement of nanomedicine, encompassing applications such as tissue engineering, biosensing, microfluidics, targeted drug delivery, and microarray technologies. Through the utilization of nanoscale therapeutic agents, nanotechnology facilitates the development of innovative nanomedicines. Nanoparticles serve as pivotal components in modern biomedicine, driving progress in drug delivery, tissue regeneration, biosensing, and nanobiotechnology. Typically, these nanoparticles are engineered nanospheres, precisely designed and structured at the atomic or molecular scale.    Inorganic nanoparticles such as magnetic and gold nanoparticles can be incorporated within micelles. Owing to their unique physicochemical properties, these inorganic nanoparticles are increasingly utilized in diverse biomedical applications, particularly in targeted drug delivery, diagnostic imaging, and therapeutic interventions. Moreover, nanostructures have been shown to facilitate the efficient transport of poorly water-soluble drugs to their specific target sites while protecting them from degradation within the gastrointestinal tract. As a result of their predominant uptake through absorptive endocytosis pathways, nanodrugs exhibit enhanced oral bioavailability.^[5]

Figure2: Nanoparticle

Nanomaterials were chosen for their capacity to overcome cosmetic restrictions, including penetration, stability, and controlled release of active ingredients.  This innovative technique allows nanomaterials to behave as active agents, expanding the potential of the products. Nanotechnology has significantly improved the efficiency of active ingredient release in conventional products, improving their value and matching consumer needs ^[6].

2. NANOTECHNOLOGY IN COSMETICS

The cutting-edge disciplines of nanotechnology and nano delivery systems involve the design, characterization, fabrication, and application of materials, devices, and systems at the nanoscale level (1–1000 nm). The integration of nanotechnology has notably advanced cosmetic science, leading to enhanced product performance and a substantial rise in global consumer demand Furthermore, the incorporation of nanomaterials has markedly increased the global market share of both cosmetic and pharmaceutical products ^[6].

These nanomaterials are primarily selected for their ability to overcome the conventional limitations of cosmetic formulations, including restricted skin penetration, poor stability, and inadequate control over the release of active ingredients. Because the Nanomaterials can also be active agents, this innovative strategy gave the products tremendous potential ^[6]. In this area, nanotechnology is crucial since it has greatly helped to overcome the drawbacks of traditional products, resulting in a more effective release of the active component and thus raising the product's value and satisfying consumer demands ^[6].

3. NANOTECHNOLOGY- NANOCARRIERS:

Nanocarriers have been shown to enhance the solubility, stability, and controlled release of active cosmetic ingredients. Studies have demonstrated that encapsulating compounds such as resveratrol and lipoic acid within nanoparticles significantly improves their chemical stability, photostability, antioxidant activity, and skin penetration ^[7]. In conclusion, nanocarriers serve as effective delivery systems that enhance the overall efficacy and performance of cosmetic products.

1. High capsulated efficiency
2. Transport of active ingredient
3. Site specific targeting
4. Controlled release
5. Increased efficacy

The primary function of nanocarriers is to deliver bioactive substances precisely to the target tissue. They can be fabricated from a wide range of materials with diverse structural architectures ^[7]. Encapsulation within nanocarriers can significantly enhance the therapeutic efficacy and bioavailability of active cosmetic ingredients while simultaneously minimizing potential adverse effects.

Figure 3: Nanocarriers

The types of nanocarriers are use in cosmetics are

• Liposomes:

 Liposomes are supramolecular aggregates that are created when amphiphilic substances, like polar lipids, are distributed throughout an aqueous solution. Because liposomes have an aqueous core, they can encapsulate both hydrophilic and hydrophobic compounds thanks to their core-shell topologies. Although the first generation of liposomes exhibited notable limitations, including instability and payload leakage, their inherent advantages were soon enhanced through integration with various synthetic and natural polymers. This innovation led to the development of lipid–polymer hybrid structures that demonstrate superior performance across diverse applications, particularly in drug delivery and diagnostic imaging ^[7]

• Gold carriers:

Numerous things can harm skin, such as pollution, exposure to ultraviolet (UV) radiation from the sun, cigarette smoke, etc. Reactive oxygen species (ROS) are produced as a result of several processes. By increasing the expression of matrix metalloproteinases (MMP), which break down collagen and elastin, an excess of ROS causes oxidative stress, which destroys cells, DNA, and protein and causes skin ageing. It is crucial to provide the skin an extra source of antioxidants so it can defend itself^.[8]

• Solid lipid carrier:

The benefits of solid lipid carrier:

1. Preventing chemical degradation of encapsulated active ingredients (such as         retinol).
2. Enabling controlled and SR of the active components.
3. Enhancing the stability of incorporated bioactive substances.
4. Improving skin penetration and absorption across the epidermal barrier, thereby    maintaining prolonged and effective therapeutic effects ^[8].

• Polymeric micelle:

Amphiphilic polymers spontaneously self-assemble at the critical micelle concentration (CMC) to form polymeric micelles—nanoscale colloidal structures characterized by a hydrophobic core and a hydrophilic shell ^[9]. These micelles arise from the intrinsic amphiphilic nature of the constituent polymers, typically composed

1. Hydrophobic segments (such as polycaprolactone, polylactic acid, or polypropylene oxide)
2. Hydrophilic blocks (such as polyethylene glycol or polyvinyl alcohol).

The hydrophobic core serves as a reservoir for poorly water-soluble drugs, enhancing their solubility and protecting them from premature degradation. The hydrophilic shell provides steric stabilization, improving the micelle’s circulation time and biocompatibility. Owing to this core–shell configuration, polymeric micelles effectively shield encapsulated drugs from oxidative degradation both in vitro and in vivo.^[10]

4.SKIN

The skin, the body’s largest organ, serves as a complex, multilayered barrier system composed of the epidermis, dermis, and hypodermis. The epidermis represents the outermost layer, while the dermis is primarily formed of dense connective tissue containing hair follicles and sweat glands. Beneath these lies the hypodermis, consisting largely of adipose and connective tissue, which provides insulation and mechanical cushioning. The stratum corneum, the outermost sublayer of the epidermis, plays a pivotal role in the barrier function of the skin due to its high lipid content and strong intercellular cohesion. Chemical substances may traverse the stratum corneum via three principal pathways appendageal, transcellular, and intercellular routes. In recent years, growing attention has focused on the interaction of nanoparticles with the skin, particularly regarding their potential risks when incorporated into topically applied cosmeceutical formulations. Nanoparticles are broadly categorized into two types:

Soluble or biodegradable nanoparticles (e.g., liposomes, Nano emulsions). Insoluble or non-biodegradable nanoparticles (e.g., titanium dioxide, fullerenes, quantum dots). Although dermal absorption of nanoparticles is generally minimal, it may occur under specific physiological or pathological conditions. Notably, cosmetic formulations are frequently used on compromised or diseased skin, where barrier integrity may be impaired, enhancing nanoparticle penetration. Most experimental evidence suggests that cutaneous nanocarriers predominantly localize within skin pores and follicular openings, with negligible diffusion beyond the stratum corneum ^[11]

Skin Ageing

Skin ageing represents a multifactorial degenerative process characterized by the progressive decline in structural and functional integrity of the skin. This phenomenon results from the synergistic effects of intrinsic (chronological and hormonal) and extrinsic (environmental and photo-induced) factors. With advancing age, there is a marked reduction in fibroblast activity, leading to diminished collagen synthesis and a decrease in dermal vascularization, ultimately resulting in loss of elasticity, increased laxity, and the formation of wrinkles ^[11].

Figure 4: Structure of skin

Numerous theories have been proposed to explain the biological mechanisms underlying skin ageing, including the genetic (DNA damage) theory, free radical theory, neuroendocrine theory, membrane theory, Hayflick limit theory, telomerase theory, and mitochondrial decline theory.

5. PATHOPHYSIOLOGY OF SKIN AGEING

Figure 5: Skin aging

According to extensive research, extrinsic factors such as ultraviolet (UV) radiation, pollution, smoking, and other environmental stress or sare responsible for the majority of skin ageing, while intrinsic (chronological) ageing contributes to only about 3% of the overall process ^[11].

Mechanism of Ageing at the Cellular and Molecular Level

The scientific understanding of ageing at the cellular and molecular level dates back to 1920, when Alexis Carrel conducted pioneering experiments using chick heart fibroblast cells, which appeared to proliferate indefinitely under optimal culture conditions. Decades later, Leonard Hayflick refined these observations and established the concept of the Hayflick limit, demonstrating that normal somatic cells possess a finite capacity for replication before entering a state of replicative senescence with advancing age, satellite cell populations gradually diminish, exhibiting reduced proliferative and myogenic capacity, which contributes to the loss of muscle tone and decreased dermal elasticity observed in aged skin.^[12]

Glycation in Ageing

Non-enzymatic glycation of proteins and lipids leads to the formation and accumulation of Advanced Glycation End-products (AGEs), which are significant contributors to cellular and extracellular degeneration during ageing. Glycation of collagen fibers induces excessive cross-linking, resulting in abnormal extracellular matrix (ECM) architecture, increased molecular rigidity, and disrupted cell–matrix interactions. Furthermore, the binding of AGEs to specific cell-surface receptors on immune cells (RAGE receptors) triggers the release of inflammatory cytokines and promotes the generation of reactive oxygen species (ROS), thereby amplifying oxidative stress and perpetuating a vicious cycle of tissue damage and inflammation.^[12]

Free Radicals in Ageing

The Free Radical Theory of Ageing (FRTA), first proposed by Denham Harman in 1954, postulates that endogenously generated free radicals play a central role in driving the biological ageing process.  The theory suggests that free radical reactions (RRs), primarily arising from mitochondrial oxidative metabolism, progressively damage cellular macromolecules such as DNA, proteins, and lipids, thereby contributing to functional decline and senescence.
Subsequent refinements of the theory emphasized that:

(a) most free radical reactions are initiated by mitochondria, with their frequency        increasing with            age.
(b) the lifespan of an organism is largely determined by the rate of mitochondrial free radical-induced damage^{. [12]}

Cellular and Molecular Mechanisms of Ageing

A prominent hallmark of ageing is tissue and organ atrophy, which often arises from reduced vascularization, hormonal insufficiency, decline in physical activity, and an overall sedentary lifestyle. Recent findings have identified impaired regenerative capacity governed by two key cell cycle control mechanisms, namely the regulation of cell proliferation and the balance between cell division and programmed cell death (apoptosis) as a fundamental contributor to the ageing process.^[13] In human fibroblasts, excessive telomere shortening disrupts normal cellular division, leading to reduced regenerative capacity and the formation of wrinkles one of the visible manifestations of ageing. Persistent telomere shortening promotes p53-mediated apoptosis, linking telomerase deficiency to cellular senescence and tissue degeneration observed in elderly individuals ^[13].

Nanotechnology in Anti-Ageing Applications

Nanotechnology represents a rapidly evolving interdisciplinary field that applies nanoscale innovations to enhance product efficacy and functionality. Nanotechnology has revolutionized anti-ageing formulations, offering improved prevention and treatment of conditions such as wrinkles, photoaging, hyperpigmentation, dandruff, and hair damage.

Traditional delivery systems have been increasingly replaced by advanced nanocarriers, including liposomes, niosomes, nanoemulsions, microemulsions, solid lipid nanoparticles (SLNs), nanostructured lipid carriers (NLCs), and nanospheres. These nanosystems offer several key advantages, such as:

TABLE1: Nanotechnology in Anti-Ageing Applications

Numerous nanoformulations have been developed for anti-ageing therapy, demonstrating superior efficacy, stability, and target specificity compared to conventional systems. These innovations exemplify how nanotechnology-driven delivery systems are shaping a new generation of cosmetic formulations designed to meet growing consumer expectations for efficacy and performance^.[14]

Role of Phytochemicals and Genetic Factors in Skin Health;

Recent studies have identified numerous phytochemicals that promote skin health and regeneration. Skin maintenance involves a complex interaction between stem cell activity and the expression of structural and regulatory genes.

Among the most critical of these are collagen genes—including COL1A1, COL1A2, COL3A1, COL5A1, and COL5A2—which encode the structural proteins responsible for the strength, elasticity, and texture of the dermis.  Protective strategies, including sun protection, a balanced diet rich in antioxidants, and consistent skincare practices, can effectively slow the progression of skin ageing.^[15]

Allopathic Medicine and Skin Epigenetic Ageing

In addition to natural and botanical compounds, Allopathic medical interventions have explored epigenetic modulation as a strategy to delay skin ageing. Several substances, collectively known as “geroprotective drugs,” have been shown to prolong tissue functionality by influencing key metabolic and epigenetic pathways. These agents regulate DNA methylation and histone acetylation patterns, and modulate microRNA (miRNA) expression, thereby maintaining cellular homeostasis and delaying the epigenetic ageing of skin cells ^[15].

Epigenetic and Molecular Modulators in Anti-Ageing Therapy

i. NAD?-Related Molecules and Sirtuin Activation

Nicotinamide adenine dinucleotide (NAD?) and its precursors have emerged as pivotal regulators of cellular metabolism and longevity. NAD? serves as a coenzyme in redox reactions and as a substrate for sirtuins (SIRT1–SIRT7), a family of NAD?-dependent deacetylases that play essential roles in DNA repair, mitochondrial function, and stress resistance. Studies have demonstrated that NAD? precursors such as nicotinamide (NAM), nicotinamide mononucleotide (NMN), and nicotinamide riboside (NR) can modulate DNA methylation patterns, influence cancer cell differentiation, and delay cellular senescence.
In skin biology, NAD? is crucial for maintaining stem cell activity and preserving cutaneous bioenergetics, thereby contributing to the delay of tissue ageing and improvement of skin function.

ii. Histone Deacetylase (HDAC) Inhibitors in Epigenetic Regulation

Histone Deacetylases (HDACs) are enzymes that remove acetyl groups from histone proteins, resulting in chromatin condensation and transcriptional repression. With ageing, dysregulated HDAC activity contributes to epigenetic silencing of longevity-associated genes and increased genomic instability.  HDAC inhibitors (HDACi) have demonstrated the ability to extend lifespan in multiple animal models, primarily by reversing age-related histone deacetylation, enhancing acetylation at pro-longevity gene loci, and reactivating cellular stress-response pathways ^[16] . In murine models, topical or systemic administration of HDAC inhibitors has been shown to prevent premature skin ageing associated with genetic disorders such as Cockayne syndrome, highlighting their therapeutic potential in cutaneous rejuvenation and DNA repair restoration.^[16]

iii. Metformin and miRNA-Mediated Epigenetic Modulation

Metformin, a well-established antidiabetic drug, has gained recognition as one of the most promising geroprotective agents due to its multi-targeted epigenetic effects. Evidence indicates that metformin can delay both intrinsic and photoinduced skin ageing through modulation of histone methylation and microRNA (miRNA) expression in senescent cells
Additionally, metformin activates SIRT1, augments DNA repair mechanisms, and promotes the differentiation of intestinal goblet cells, which collectively contribute to reduced systemic inflammation and improved microbiome balance  .These pleiotropic effects extend beyond the skin, reinforcing metformin’s role as a systemic anti-ageing and anti-inflammatory compound^.[17]

iv. β-Glucan and Histone Methylation Regulation

β-glucans enhance the skin’s innate defence mechanisms by modulating immune cell responses within the epidermis and dermis. Through this regulation of the cutaneous immune network, β-glucans not only protect against oxidative and environmental stress but also contribute to delaying the onset of visible signs of ageing. Because the immune responsiveness of aged skin is markedly reduced, elderly individuals experience impaired cutaneous defence mechanisms, rendering them more susceptible to infections and delayed wound healing ^[17,18].

5. HAIR

Mammals are characterized by the presence of hair, a distinctive feature that serves multiple physiological and functional roles, including protection, thermal regulation, facilitation of sweating and pheromone dispersion, enhancement of sensory perception, and, in certain species, color-based camouflage. In modern society, where hair care and styling play an essential role in self-image and grooming for both men and women, it has become increasingly important for dermatologists to possess a comprehensive understanding of hair products, their mechanisms of action, ingredients, efficacy, and the various cosmetic procedures employed in hair management ^[19]

Hair cosmetics are broadly categorized into two principal types:
 (1) products that exert temporary effects on the hair, such as shampoos, conditioners, sprays,and temporary colorants.

  (2) those that induce long-lasting or permanent alterations to the hair shaft, including relaxers, bleaches, permanent waves, and permanent dyes.

Owing to their wide range of formulations, diverse applications, and ease of availability, hair care preparations—whether used for cosmetic enhancement or therapeutic purposes—have gained substantial popularity among consumers ^[19]. Recent advances in cosmetic science highlight the potential of nanomaterials to enhance the performance of active ingredients in hair care products. This review begins with an overview of the structure and physiology of hair, followed by an exploration of current cosmetic and therapeutic approaches. Particular emphasis is placed on the development of innovative nano-based formulations designed to advance the field of hair treatment and care ^[19].

Hair Anatomy:

The structural organization of hair has been extensively studied since the 1930s, when X-ray diffraction techniques were first employed to elucidate the arrangement of hair fibres. Hair comprises a flexible filament of hard-cornified epithelium, continuously generated by the hair follicle embedded within the dermis, and the hair shaft, which represents the visible portion emerging          above   the       skin                  surface^[20].

Figure 6 : Structure of hair: (A) Hair follicle and (B) Hair shaft.

Anatomically, hair can be broadly divided into two principal parts:

A. Hair Follicle

B. Hair Shaft

1. Hair Follicle

The formation of the hair follicle during foetal skin development is governed by precisely regulated ectodermal–mesodermal interactions.

Structurally, the follicle resembles a tubular or stocking-like arrangement and is divided into three main segments:

• • • Lower segment: bulb and suprabulbar region
    • Middle segment: isthmus
    • Upper segment: infundibulum

Melanocyte stem cells, located within the bulge area, sustain pigment production throughout successive hair cycles, while melanocytes in the bulb region are responsible for the pigmentation of newly formed hair fibers ^[20].

2. Hair Shaft

The hair shaft is composed primarily of keratinized, non-living cells. It consists of three concentric structural layers—the cuticle, cortex, and medulla—which are held together by the cell membrane complex, functioning collectively as a mechanically integrated unit.

5. Cuticle

The cuticle is the outermost layer, consisting of dead, flattened cells arranged in a stratified, scale-like pattern.  Beneath the epicuticle lies the exocuticle, a 50–300 nm thick cysteine-rich layer that contains most of the cysteine residues within the scales.

5. Cortex

The cortex, located between the cuticle and the medulla, comprises elongated, fibrous keratinized cells arranged in twisted bundles. It contains melanin granules, which determine the natural colour of hair. Disruption of the cortex’s extensive disulfide bond network can lead to increased trans-epidermal water loss and facilitate the ingress of foreign substances, thereby compromising hair integrity ^[21].

5. Medulla

The medulla forms the innermost core of the hair shaft and is composed of cells with low disulfide bond content, high lipid concentration, and trichohyalin as a major structural protein^[21].

6.  Cosmetics for Hair and Medical Care

The unique anatomical and physiological characteristics of the hair follicle allow it to be modified by a wide range of cosmetic and medical formulations available to consumers. Cosmetic hair products primarily serve to cleanse, protect, and condition the hair, while also stimulating growth, enhancing shine, and altering colour to meet individual preferences ^[22]. The growing overlap between cosmetic and pharmaceutical approaches in hair care—often termed cosmeceutical innovation—has driven the development of multifunctional products that combine aesthetic enhancement with dermatological efficacy.^[22]

7. Hair Care and Treatment Formulations Based on Nanotechnology

According to the European Union Cosmetic Products Regulation (EC No. 1223/2009), a nanomaterial is defined as “an insoluble or bio persistent, intentionally manufactured material with one or more external dimensions, or an internal structure, on the scale of 1 to 100 nanometres”. In recent years, the integration of nanostructures—such as silver (Ag), gold (Au), and titanium dioxide (TiO?) nanoparticles—into hair care formulations has attracted significant attention. These nanomaterials not only enhance the optical and aesthetic properties of cosmetic products but also impart biological activity, contributing to improved hair health and protection.^[23] The application of nanotechnology in hair cosmetics and therapeutics represents a promising advancement in targeted and controlled delivery systems. Nanocarriers are particularly valuable for formulating products intended for both cosmetic enhancement and medical treatment of hair and scalp disorders. The key advantages of using nanocarriers in hair formulations include their ability to:

1. Improve efficacy while minimizing toxicity and irritation of active compounds.
2. Enhance compound stability against environmental degradation.
3. Provide controlled and sustained release of active ingredients.
4. Facilitate deeper follicular and dermal penetration of hydrophilic or moderately lipophilic substances.^[23]

8. Nano-Based Formulations for Hair Cosmetics:

This section will concentrate on nano-based formulations specifically designed for hair cosmetic purposes, including both organic (lipid- or polymer-based) and inorganic (nanotube-, nanosheet-, or inorganic NP-based) formulations.  There have been reviews of nanomaterial-based cosmetic formulations and cosmeceuticals ^[24].

9.A. Classification of Nano-Based Hair Formulations

Nano-based hair formulations can be broadly categorized according to the nature of the nanocarrier material, which influences their physicochemical properties, stability, and interaction with biological tissues. These systems are generally divided into organic and inorganic nanocarriers, each offering unique advantages for targeted hair and scalp delivery.^[24]

1.1 Nanocarriers Based on Organic Materials

Organic nanocarriers are primarily composed of biodegradable and biocompatible polymers or lipids, making them suitable for cosmetic and therapeutic applications. They offer flexibility in encapsulating both hydrophilic and lipophilic agents and can enhance penetration through the hair follicle and scalp while minimizing toxicity^.[25]

1.1.1 Polymer-Based Systems

Polymeric nanocarriers, such as dendrimers, nanospheres, and nanocapsules, are versatile systems engineered from synthetic or natural polymers.

• Dendrimers possess a highly branched, tree-like structure with multiple surface functional groups, allowing for high drug-loading capacity and controlled release.
• Nanospheres are matrix systems where the active ingredient is uniformly dispersed throughout the polymeric network, providing sustained release and protection against degradation.
• Nanocapsules feature a core–shell structure, in which the active compound is enclosed within a polymeric membrane, enabling targeted delivery and reduced irritation potential.

These polymer-based systems are widely explored for delivering active compounds that promote hair growth, prevent hair loss, and improve hair strength and texture^.[25]

1.1.2 Lipid-Based Systems

Lipid-based nanocarriers, including solid lipid nanoparticles (SLNs), liposomes, and nanostructured lipid carriers (NLCs), have gained substantial attention in hair formulations due to their superior compatibility with biological membranes and enhanced stability.

• SLNs provide a solid lipid matrix that protects sensitive compounds from oxidation and degradation.
• Liposomes, composed of phospholipid bilayers, facilitate deep follicular penetration and efficient encapsulation of both hydrophilic and lipophilic molecules.
• NLCs, the next generation of lipid carriers, combine solid and liquid lipids to improve loading efficiency and prevent drug expulsion during storage.^[25]

These systems are particularly beneficial in delivering vitamins, antioxidants, and botanical extracts to the hair shaft and follicle.

1.2 Nanocarriers Based on Inorganic Materials

Inorganic nanocarriers are composed of materials such as silica, carbon, or layered minerals. They possess excellent mechanical strength, tunable surface chemistry, and high thermal stability, making them effective platforms for sustained and targeted delivery in hair applications.^[25]

1.2.1 Nanotube-Based Systems

Nanotubes, including halloysite and carbon nanotubes (CNTs), are cylindrical nanostructures capable of encapsulating a wide range of active agents within their hollow cores.

• Halloysite nanotubes (HNTs) are naturally occurring aluminosilicate minerals with high biocompatibility and a strong affinity for keratin, making them useful in hair repair and protection formulations.
• Carbon nanotubes exhibit high mechanical strength and conductivity; when surface-functionalized, they can enhance penetration and targeted delivery while maintaining low toxicity.^[25]

1.2.2 Nanosheet-Based Systems

Nanosheets, such as layered double hydroxides (LDHs) and graphene oxide nanosheets, are two-dimensional materials characterized by their large surface area and modifiable surface functionalities.

• LDHs enable controlled intercalation and sustained release of active ingredients.
• Graphene oxide nanosheets, with their high adsorption capacity and biocompatibility, are emerging as potential carriers for antioxidants and peptides in advanced hair treatment formulations.^[25]

Figure 7 : Structure of liposome, lipid nanoparticle, micelle.

1. 1. Nanocarriers Based on Organic Materials
   2. Systems Based on Polymers (such as Dendrimers, Nanospheres, and Nanocapsules)

Polymer-based nanocarriers have emerged as highly versatile systems in hair cosmetic formulations due to their tunable structure, biocompatibility, and ability to encapsulate both hydrophilic and hydrophobic active ingredients. Recent developments have focused on their application in reducing the cytotoxic effects of conventional hair dye components, such as p-phenylenediamine (PDA), which is known for its potential allergenicity and oxidative stress–inducing properties.These nanoparticles demonstrated effective encapsulation of bioactive agents while enhancing adherence to the hair surface and improving product stability. As summarized in Table 1, numerous polymer-based nanomaterials—such as dendrimers, nano capsules, and chitosan derivatives—have been successfully engineered for use in nano-enabled hair formulations. Collectively, these systems offer enhanced delivery efficiency, reduced cytotoxicity, and controlled release profiles, establishing them as pivotal tools in the advancement of next-generation hair cosmetics. ^[24,25]

Figure 8 : Structure of nanosphere, nano capsule, dendrimer

1. 1. 1. Systems Based on Lipids (such as Solid Lipid Nanoparticles, Liposomes, and Nanostructured Lipid Carriers)

Lipid-based nanocarriers have gained considerable attention in the field of hair cosmetics due to their biocompatibility, ability to encapsulate both hydrophilic and lipophilic substances, and affinity for biological membranes. These systems—including solid lipid nanoparticles (SLNs), liposomes, nanostructured lipid carriers (NLCs), and nanoemulsions (NEs)—offer significant advantages such as enhanced stability of active ingredients, improved scalp penetration, and sustained release profiles, making them particularly suitable for formulations targeting hair conditioning, repair, and protection.Research into the use of lipid nanoparticles for improving hair texture and moisture retention has shown promising results. Sonneville-Aubrun et al.  developed nanoemulsions (NEs) composed of various cosmetic oils dispersed in an aqueous glycol phase and stabilized by a surfactant blend of disodium stearoyl glutamate and PEG-8 isostearate. They developed thermodynamically stable oil-in-water nanoemulsions using non-ionic surfactants, which improved the dispersion and surface adherence of silicone oil on hair fibres. This nanoemulsion approach enhanced hair softness, shine, and manageability while minimizing product buildup.Further advances in lipid nanotechnology have focused on nanostructured lipid carriers (NLCs)—a second-generation system derived from SLNs that combines solid and liquid lipids to enhance drug-loading capacity and prevent crystallization during storage. Müller et al. ^[25] first demonstrated the potential of NLCs in cutaneous and cosmetic applications, highlighting their ability to improve the stability and penetration of active compounds in topical formulations. Building upon this concept, Prasertpol and Tiyaboonchai designed both negatively charged (N-NLCs) and positively charged (P-NLCs) formulations and evaluated their performance in hair split-end repair.  Overall, lipid-based nanocarriers provide a robust platform for enhancing the efficacy, sensory appeal, and long-term stability of hair care formulations. Their ability to mimic natural lipid environments and deliver active agents selectively to the hair shaft and follicle underscores their growing role in the design of next-generation nano-enabled hair cosmetics ^[25].

Figure 9 : Structure of liposomes

1.2 Nanocarriers Based on Inorganic Materials

1.2.1 Systems Based on Nanotubes (such as Halloysite and Carbon Nanotubes)

Carbon Nanotubes (CNTs)

Since their discovery by Sumio Iijima in 1991, carbon nanotubes (CNTs) have become one of the most extensively studied nanomaterials in biomedical and cosmetic sciences due to their unique structural, mechanical, and physicochemical properties. These include an exceptionally high aspect ratio, large specific surface area, chemical tunability, and remarkable nanoscale size stability. Structurally, CNTs consist of graphitic carbon sheets rolled into cylindrical nanostructures, forming either single-walled carbon nanotubes (SWCNTs) or multiwalled carbon nanotubes (MWCNTs). SWCNTs are composed of a single graphene cylinder with diameters ranging from 0.4 to 2 nm, while MWCNTs consist of multiple concentric graphene cylinders with inner tube diameters of 1–3 nm and outer diameters extending up to 100 nm, depending on synthesis conditions. Their hollow structure enables the encapsulation and transport of various biologically active compounds, making them promising candidates for drug delivery, gene transport, and protein immobilization. When appropriately functionalized, CNTs have been successfully employed as nanocarriers for anticancer agents, nucleic acids, and peptides, demonstrating controlled release and targeted cellular uptake ^[26]. Furthermore, CNTs possess excellent optical absorption and thermal conductivity, facilitating their use as mediators in photothermal (PTT) and photodynamic (PDT) therapies, where they enable precise destruction of pathological cells through light-induced heating or reactive oxygen species generation. Through chemical functionalization, CNTs were modified with carboxyl (–COOH) and amine (–NH?) groups to increase electrostatic interactions and hydrogen bonding with keratin, thereby improving affinity and colour deposition on hair fibres (Fig. 10A).Alternatively, physical functionalization techniques were employed, wherein CNTs were coated with surfactants, biopolymers, or organic polyamines to enhance their dispersion stability and compatibility with aqueous cosmetic formulations (Fig. 10B^).[26] This approach not only ensures even pigment distribution but also contributes to improved colour fastness, reduced toxicity, and enhanced hair texture following application. Collectively, CNT-based systems represent a cutting-edge innovation in nano-enabled hair care, combining cosmetic functionality (e.g., durable, uniform colouring) with potential

Figure 10 A- chemical functionalization & 10 B- physical functionalization

biomedical applications (e.g., targeted follicular delivery or scalp therapy). Ongoing research aims to further optimize CNT biocompatibility, surface modification techniques, and environmental safety, ensuring their safe integration into next-generation hair formulations ^[25,26].

Halloysite Clay Nanotubes (HNTs)

 In comparison to widely utilized carbon nanotubes (CNTs), halloysite clay nanotubes (HNTs) represent a naturally occurring, biocompatible, and cost-effective nanomaterial with remarkable potential for use in cosmetic and biomedical formulations. Their excellent functional ability, low toxicity, and abundance in natural clay deposits make them an environmentally sustainable alternative to synthetic nanotubes.  Structurally, HNTs possess a tubular morphology formed through the rolling of flat aluminosilicate kaolinite layers approximately 15–20 times, resulting in multilayered nanostructures with distinct inner and outer surface chemistries ^[26] The tubular architecture of HNTs facilitates dual-mode loading of active compounds—either encapsulation within the lumen or adsorption onto the external surface—allowing for controlled and sustained release of incorporated agents. Moreover, their large surface area and high adsorption capacity make HNTs particularly advantageous in the formulation of skin cleansers, exfoliants, and protective coatings, where enhanced adsorption contributes to deep cleansing and pollutant removal ^[26]. In the field of hair care, several studies have underscored the promising role of HNTs as functional nanocarriers. Cavallaro et al.  developed a halloysite/keratin hybrid nanocomposite as a protective hair treatment designed to enhance photoprotection and mechanical resilience of hair fibers. Their investigation revealed that pH variations significantly influenced the structural, thermodynamic, and colloidal stability of the HNT/keratin core–shell system, thereby optimizing its performance as a photoprotective coating for hair. Overall, HNTs offer a biocompatible, versatile, and sustainable nanoplatform for developing next-generation cosmetic and therapeutic hair formulations, capable of targeted                                      delivery, enhanced durability, and improved environmental safety compared to conventional nanocarriers^{.  [24,25,26]}

FIGURE 11- HNTs