Development And Characterization Of Peel-Off Gel Masks Incorporating Activated Charcoal And Salicylic Acid For Enhanced Skin Radiance And Rejuvenation

Facial masks have long been integral to skincare routines, revered for their ability to deliver concentrated treatments and provide immediate, visible improvements to the skin. Among various types of facial masks, peel-off gel masks have garnered significant attention due to their unique mode of application and numerous benefits. These masks are particularly appreciated for their ability to form a film on the skin, which, upon removal, helps in the physical exfoliation of dead skin cells and impurities [1], [2]. The primary benefits of peel-off gel masks include deep cleansing, exfoliation, and enhanced skin texture. These masks work by creating a cohesive film that adheres to the skin’s surface. When the mask is peeled off, it removes the film along with dead skin cells, dirt, and oil from the pores [2], [3]. This process helps to unclog pores, reducing the likelihood of acne and other skin issues, and leads to a clearer and smoother complexion [3], [4]. Essential components of peel-off masks typically include film-forming agents, exfoliating agents, and various active ingredients tailored to specific skin concerns [5].  The incorporation of activated charcoal and salicylic acid in peel-off masks is expected to offer synergistic benefits for enhancing skin radiance and rejuvenation. Activated charcoal is well-known for its exceptional adsorptive properties, enabling it to remove impurities, toxins, and excess oil from the skin, thus providing a deep cleansing effect [6], [7]. Salicylic acid, a beta hydroxy acid, is renowned for its exfoliating abilities that help unclog pores, reduce acne, and promote cellular turnover, leading to improved skin texture and clarity [8]. The rationale for incorporating activated charcoal and salicylic acid into peel-off masks lies in their complementary mechanisms of action. Activated charcoal effectively binds to impurities, aiding in their removal from the skin’s surface, while salicylic acid penetrates the pores to dissolve sebum and exfoliate dead skin cells from within. This combination is likely to ensure a thorough cleansing and exfoliation process, crucial for maintaining healthy and radiant skin. Regular use of peel-off masks containing activated charcoal and salicylic acid can also lead to noticeable improvements in skin clarity, texture, and overall radiance. The deep cleansing action helps minimize the appearance of pores, while salicylic acid’s exfoliating properties promote a smoother and more even skin tone. Moreover, by exfoliating dead skin cells and removing impurities, alongside the occlusive properties of the mask, it enhances the absorption of subsequent products containing active substances, thereby maximizing their effectiveness. These results not only improve the appearance of the skin but also promote overall skin health and rejuvenation [1], [3], [9], [10].This study aims to develop and characterize a peel-off gel mask formulation incorporating activated charcoal and salicylic acid to enhance skin radiance and rejuvenation. The research will evaluate the physicochemical properties of the developed formulations, including organoleptic characteristics, homogeneity, pH, spreadability, and drying time. Additionally, the overall impact of the masks on skin irritation, smoothness, and tightness will be assessed through skin evaluations and volunteer feedback, examining user acceptability and satisfaction to ensure the mask's potential as an effective and innovative skincare product.

MATERIALS AND METHODS

Materials

All chemicals used were of analytical grade and were commercially available. These include: Phenoxyethanol, EDTA disodium, and Propylene glycol, which were obtained from Himedia (Mumbai, India); Polyvinyl alcohol (PVA), fully hydrolyzed (Mw approx. 72000), from Merck (Darmstadt, Germany); hydroxypropylmethylcellulose (HPMC) from Pure Chemical (India); activated charcoal from Labtech (India); salicylic acid from Medisco Inc. (Irving, TX, 75063, USA); ethanol 96% (EtOH) from Vectoria (Sana'a, Yemen); and glycerin and distilled water from Dieda Corporation for Drugs Med Appliances (Taiz-Al-Howban, Yemen).

Preparation of Peel-Off Gel Masks

The peel-off gel mask formulations incorporating activated charcoal and salicylic acid were prepared according to the formula presented in Table 1. The compositions of the peel-off gel masks consist of polyvinyl alcohol as a film-forming agent, hydroxypropyl methylcellulose or gelatin as gelling and matrix forming polymer, glycerin and propylene glycol as plasticizers, ethanol as a solvent, and phenoxyethanol as a preservative.

Initially, heat the required amount of water to 80°C in a beaker and slowly add PVA to the hot water while stirring continuously until it completely dissolves. For formulations F1, F3, F5, and F7, dissolve HPMC in a small portion of water at room temperature, and then add this to the PVA solution. For formulations F2, F4, F6, and F8, heat a small portion of water to 40°C and dissolve gelatin, then add the gelatin solution to the PVA while stirring continuously. Next, dissolve sodium EDTA in a small amount of water and add it to each mixture. Add glycerin and propylene glycol to each mixture while stirring. For the respective formulations, add the required amounts of activated charcoal and salicylic acid to the mixture, ensuring thorough mixing. Gradually add ethanol and phenoxyethanol to the mixture while stirring continuously, ensuring the mixture is homogeneous. Continue stirring for an additional 30 minutes. After preparation, each gel formulation was allowed to rest overnight at 8 °C to release any air incorporated during homogenization before conducting any evaluations [6], [11].

Organoleptic Properties

The organoleptic properties of the masks were assessed based on parameters such as color, odor, and consistency through visual inspection. This evaluation aimed to detect any changes in these characteristics. Consistency and color were evaluated visually, while odor was assessed by smelling the product [3], [12].

Homogeneity Test

The homogeneity test was conducted by placing 0.1 grams of the gel between two glass slides and checking whether the surface was evenly smooth and the base was homogeneous. The preparation is considered homogeneous if no coarse particles can be palpated [4].

pH Test

A total of 1 gram of gel was weighed and dissolved in 10 mL of distilled water, then stirred to ensure uniformity. The pH meter was then immersed, and the results were recorded [4].

Spreadability Test

A total of 1 gram of the peel-off gel preparation is placed between two horizontal glass plates (10 cm × 20 cm). Then, a standard weight of 25 grams is applied to the upper plate, and the spreading diameter is measured after 1 minute [5], [13].

Drying Time Test

One gram of each formula was weighed and evenly spread using a mask brush over a 6.0 x 3 cm area on the forearm skin. The application was allowed to dry until the film could be peeled off, and the drying time was recorded [4].

Irritation test

An irritation test, based on the modified method of Budiman et al. (2017) [14], was conducted by applying a specified amount of the sample to the forearm skin surface of a group of 10 volunteers. The sample was left on for 20–30 minutes before being removed, after which the skin was observed for any signs of itching, redness, or swelling. A positive irritation reaction is indicated by the presence of redness, itching, or swelling on the treated skin of the forearm [15]. Ethical approval for the experimental procedure's irritation testing was obtained from the University Ethics Committee.

Hedonic Test

A group of 10 volunteers, representative of the target audience for peel-off gel masks, was recruited for this study. The inclusion criteria ensured a variety of skin types and ages over 18, excluding those with sensitive skin or allergies. Volunteers were provided with clear, standardized instructions on the application of the peel-off mask. This included guidelines on the amount of product to use, the duration for which it should be left on the skin, and the proper method of removal. Ensuring consistent application across participants was critical for the validity of the results [16]. Ethical approval for the experimental procedure's irritation testing was obtained from the University Ethics Committee. Each Volunteer was asked to apply the selected formulation of peel-off gel mask on the forearm area and leave it for about 15 minutes before cleaning with a wet tissue. The volunteers were then asked for their personal responses regarding likes or vice versa (dislike) in terms of ease of application, comfort during wear/stinging, ease of removal, immediate effects on the skin (smoothness, brightness/radiance, tightness), and overall satisfaction. These criteria addressed both functional and experiential aspects of the mask [16]. The results offered valuable insights into consumer preferences, guiding further development and refinement of the peel-off gel mask formulation.

Data Analysis

The experiments were conducted in triplicate and the results were reported in terms of the mean and standard deviations. The mean parameters were analyzed using one-way analysis of variance (ANOVA) to determine the significance different at the level set at 0.05. Statistical analysis was conducted using Microsoft Excel (Microsoft Corporation, Redmond, USA).

RESULTS AND DISCUSSION

Organoleptic Properties

The organoleptic test aimed to evaluate the mask’s color, odor, and consistency, providing insights into the sensory attributes of the final product. All formulations were semi-solid in consistency and smooth in texture. The results of the organoleptic assessment for the prepared peel-off gel masks are summarized in Figure 1 and Table 2.

       
           
       
   Figure 1: Formulations of Peel-Off Gel Masks

Homogeneity Test

The homogeneity test is conducted to assess the uniformity and even distribution of particles within the formulation. Ensuring the homogeneity of mask preparations is crucial, as it significantly impacts the effectiveness of the active ingredients present in the mask [17], [18]. The formulation must be smooth and soft upon application to the skin, devoid of any grittiness. The results of the homogeneity test indicated that all formulations were homogeneous, as evidenced by the absence of coarse particles, grittiness, color migration, and secondary particle aggregation. This outcome suggests that the selected ingredients were appropriate and did not interact in a manner that caused clumping. Additionally, the mask preparation process adhered to the established procedure, ensuring that all ingredients were fully dissolved and evenly distributed. The manufacturing process is important in achieving homogeneity. Consistent and uniform stirring, along with maintaining an appropriate temperature for dissolving and blending the ingredients, are essential to ensure the homogeneity and effectiveness of the final product.

pH Test

As shown in table 3, the pH values of the peel-off gel mask formulations varied considerably, ranging from acidic to neutral. Formulations F1 through F4 exhibited near-neutral pH values, while formulations F5 through F8 demonstrated more acidic pH levels.

Spreadability Test

Spreadability testing is carried out to determine the ability of the prepared peel-off gel masks to spread when applied to the skin. This term describes how easily a gel spreads over the skin or the affected area upon application. The therapeutic efficacy of a formulation is influenced by its spreading value, which is determined by the rate and duration of shear force during application and the formulation's viscosity [3]. According to the literature, a good peel-off mask gel should have a dispersion ability of 5-7 cm [3].

All formulations were within the range of good spreadability, indicating that they have optimal spreading ability on the skin (see Table 3). F2 and F4 demonstrated the highest spreadability, followed by F6 and F8, indicating a smoother and more even application. On the lower end, F1, F3, and F5 showed less spreadability. Based on the one-way ANOVA test, the significant results were p=0.0001 (P <0>

Drying Time Test

The film drying time test was conducted by observing the time required for the preparation to dry completely, starting from the application of the peel-off gel mask on the skin until a dry layer was formed. Measurements of drying time revealed a range of results, reflecting the time required for the masks to set on the skin, as shown in Table 3. Ideally, the peel-off gel mask should dry within 15 to 30 minutes [14]. It was observed that all preparations dried within this range. Formulation F4 exhibited the shortest drying time among the tested formulations, with a mean of 17.67 ± 1.53 minutes. In contrast, formulations F1, F3, F5, and F7 demonstrated longer drying times, ranging from 21 to 23 minutes. Meanwhile, formulations F2, F4, F6, and F8 required a shorter duration to dry completely, ranging from 17 to 19.5 minutes.

The differences in drying time indicate variations in the composition and physical properties of the formulations, which can influence user experience and effectiveness. Formulations F1, F3, F5, and F7 demonstrated longer drying times than the other formulations due to their HPMC content. These results are consistent with the spreadability test results. Formulations F2, F4, F6, and F8, which contain gelatin, exhibited higher spreadability values due to their thinner consistency, which enhances spreadability and facilitates faster water evaporation. This suggests that these formulations might be preferable for users seeking quick application and removal. The one-way ANOVA test showed significant results with p=0.0028 (P < 0>

Irritation Test

The irritation test was conducted to assess the safety level of the gel peel-off masks. The skin changes of the volunteers were examined visually, with the parameters observed being the presence of redness, itching, or swelling [15].

The test involved 10 volunteers, with the peel-off gel mask applied to the skin surface of their forearms.  The results showed that all volunteers had negative reactions for the parameters of irritation. From the results of the irritation test, it can be concluded that the prepared peel-off gel mask is safe to use and exhibits good peel-off properties without leaving any residue. It showed good compatibility with all skin types without causing any irritation or itching.

Hedonic Test

Table 4 and Figure 2 illustrate the feedback collected from volunteers after the application of the peel-off gel masks. Additionally, Figure 3 displays images of the forearms of the volunteers taken during the mask application. Furthermore, Figure 4 is included to show images of the skin on the inner forearms before and after the mask application. These images are provided to visually illustrate the treatment effects.

Most formulations scored highly in ease of application, with F2, F3, F4, F7, and F8 all achieving a score of 100%, indicating that the volunteers found these formulations very easy to apply. Regarding comfort during wear, all formulations scored between 80% and 100%, indicating that the masks were generally comfortable to wear. Formulation F1 received the highest score of 100%, indicating maximum comfort. Formulations F2, F3, F4, F5, F6, F7, and F8 scored 90% or above in the Ease of Removal criterion, indicating that the masks were easy to remove for most participants as seen in Figure 3. Furthermore, the peel-off gel masks from all formulations did not exhibit signs of cracking or tearing during peeling, which can be attributed to their high film integrity, as demonstrated in the Figure 3. Temporary stinging was evaluated, and most formulations scored very low in this category, with scores ranging from 0% to 20%. This indicates minimal to no stinging sensation during use, which is a favorable outcome. The very low stinging sensation observed in formulations F5, F6, F7, and F8 was attributed to their salicylic acid content. This sensation was temporary and did not cause any discomfort to the volunteers. It is noteworthy that the presence of activated charcoal in combination with salicylic acid in the same formulation helps to reduce the stinging sensation, as observed in formulations F7 and F8. The majority of formulations (F5 to F8) received a score of 100% for skin smoothing, indicating excellent effects. These formulations also achieved a score of 100% for skin brightening, suggesting they were highly effective in enhancing skin brightness. Additionally, formulations F5 to F8 attained a score of 100% for skin tightness, demonstrating their efficacy in providing the desired skin-tightening effect.  The hedonic test results indicate that formulations F5, F6, F7, and F8 performed exceptionally well across most criteria, particularly in terms of skin smoothing, brightening, and tightening effects. These observable results are a direct consequence of the inclusion of salicylic acid in the masks, along with the synergistic and enhancing effects of activated charcoal. Figure 4 illustrates some of the results obtained for one of these formulations, F8, showing the differences before and after application.  Salicylic acid remains a vital active ingredient in many over-the-counter (OTC) topical drug products. As a keratolytic agent, salicylic acid facilitates the disaggregation of corneocytes in the upper stratum corneum, thereby promoting the shedding of scales and softening the stratum corneum. Currently, salicylic acid products available on the market typically have a pH ranging from 3 to 4 [20].