Development and validation of an ultraviolet-visible spectrophotometric method for determination of phenylethyl resorcinol in new topical nanoemulsions

Ultraviolet spectrophotometry as method to determine the concentration of β-myrcene released from chitosan in aqueous medium

Myrcene (β-myrcene), found in essential oils from plant species such as hops and cannabis, has many advantageous properties, but its use is limited due to volatility and low solubility in water. One way to circumvent these limitations is to encapsulate the essential oils in a polymer matrix. However, these hydrophobic molecules are difficult to quantify when dispersed in water. Seeking to study the release of this terpene in drug release tests from polymeric matrices, this work aimed to develop an easy and cheap UV spectrophotometric method for the quantification of β-myrcene in aqueous medium. To achieves this goal, samples were prepared in 0.05% (w/v) polysorbate 80 solution, with concentrations of β-myrcene ranging from 0.01% to 0.1% (v/v), and were analyzed at 226 nm. Each sample was analyzed in triplicate and repeated on three different days, to evaluate the repeatability of the results. The results were subjected to Q, F and Student's t-tests. The regression parameters obtained for β-myrcene were above 0.99 and through statistical analysis, it was possible to confirm the repeatability for the results. The values of the limits of detection and quantification indicated that the method is not affected by intrinsic factors of the equipment. The results of accuracy, robustness and selectivity showed recovery rates within acceptable limits. This demonstrates that the quantification of β-myrcene in aqueous medium by UV spectrophotometry is feasible.

Enhancement of Skin Wound Healing by rhEGF-Loaded Carboxymethyl Chitosan Nanoparticles

The self-assembly of hydrophobically modified polymers has become a research hotspot due to its wide application in the biomedical field. Recombinant human epidermal growth factors (rhEGFs) are molecules that are able to enhance wound healing; however, they have a short half-life and require sustained action to enhance their mitogenic effect on epithelial cells. Here, we proposed a new delivery system to avoid the inhibition of rhEGF by various enzymes, thus improving its bioavailability and sustained release. The amphiphilic polymer was composed of conjugated linoleic acid (CLA) and carboxymethyl chitosan (CMCS), which were further characterized by fourier transformed infrared spectroscopy (FTIR) and 1H nuclear magnetic resonance (1H NMR). Then, the self-assembly behavior of CLA-CMCS (CC) polymer in water was observed in which the particle size of CC decreased from 196 to 155 nm with the degree of CLA substitution increasing. The nanoparticles were loaded with rhEGF and the maximum rhEGF loading efficiency (LE) of CC3 nanoparticles was 82.43 ± 3.14%. Furthermore, CC nanoparticles (NPs) exhibited no cytotoxicity for L929 cells, and cell proliferation activity was well preserved after rhEGF loading to CC-NPs and was comparable to that of free rhEGF. Topically applied rhEGF:CC-NPs significantly accelerated the wound-closure rate in full thickness, which was most probably due to its sustained release and enhanced skin permeation. In conclusion, carboxymethyl chitosan-based nanoparticles were constructed and showed good cytocompatibility. Moreover, these findings also demonstrated the therapeutic potential of rhEGF:CC-NPs as a topical wound-healing drug carrier.

Polymeric nanoparticles based on carboxymethyl chitosan in combination with painless microneedle therapy systems for enhancing transdermal insulin delivery

Biodegradable nanoparticles (NPs) have been frequently used as insulin transdermal delivery vehicles due to their grand bioavailability, better encapsulation, controlled release and less toxic properties. However, the skin's barrier properties prevent insulin-loaded NP permeation at useful levels. Nowadays, microneedles have been spotlighted as novel transdermal delivery systems due to their advantages such as painlessness, efficient penetration and no hazardous residues. Herein, we introduce polymeric nanocarriers based on carboxymethyl chitosan (CMCS) for insulin delivery, combining with microneedle therapy systems, which can rapidly deliver insulin (INS) into the skin. The resulting CMCS-based nanocarriers are spherical nanoparticles with a mean size around 200 nm, which could generate supramolecular micelles to effectively encapsulate insulin (EE% = 83.78 ± 3.73%). A nanocrystalline microneedle array (6 × 6, 75/150 μm) was used to penetrate the stratum corneum (SC) for enhancing transdermal insulin delivery, while minimizing the pain sensation caused by intravenous injection. Compared with the transdermal rate of passive diffusion [2.77 ± 0.64 μg (cm-2 h-1)], the transdermal rate of the insulin-loaded NP combined with microneedle penetration shows a 4.2-fold increase [10.24 ± 1.06 μg (cm-2 h-1)] from permeation experiment in vitro. In vivo hypoglycemic experiments demonstrate the potential of using nanocarrier combination with microneedle arrays for painless insulin delivery through the skin in a clinical setting. Thus, the developed combination scheme of nanoparticles and microneedle arrays offers an effective, user-friendly, and low-toxicity option for diabetes patients requiring long-term and multiple treatments.

Fabrication of Carboxylmethyl Chitosan Nanocarrier via Self-Assembly for Efficient Delivery of Phenylethyl Resorcinol in B16 Cells

Micro-molecular drugs have special advantages to cope with challenging diseases, however their structure, physical and chemical properties, stability, and pharmacodynamics have more requirements for the way they are delivered into the body. Carrier-based drug delivery systems can circumvent many limited factors of drug delivery and increase their bioavailability. In this context, stable drug nanocarriers of alkaline amino acids (arginine, Arg) modified conjugated linoleic acid-carboxymethyl chitosan (CLA-CMCS) conjugate were developed, which could generate supramolecular micelles to effectively encapsulate the tyrosinase inhibitor phenylethyl resorcinol (PR). The resulting CCA-NPs were spherical nanoparticles with a mean size around 175 nm. The 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) assay and cellular uptake investigation demonstrated that the CCA-NPs were non-cytotoxic and had excellent cell transport ability. In addition, these CCA-NPs were able to effectively deliver PR and inhibited melanin formation to reduce pigmentation by enhancing cellular uptake. In conclusion, our research indicated that nanocarriers based on self-assembly amphiphilic polymers constituted a promising and effective drug delivery system in hyperpigmentation targeting.

Development of a carboxymethyl chitosan functionalized nanoemulsion formulation for increasing aqueous solubility, stability and skin permeability of astaxanthin using low-energy method

In this research, firstly astaxanthin (ASX)-loaded nanoemulsions (NEs) were produced using a convenient low-energy emulsion phase inversion method. The optimised ASX-NEs were prepared in the presence of Cremophor^® EL and Labrafil^® M 1944 CS, with a surfactant-to-oil ratio of 4:6. The ASX-NE droplets were spherical with a mean droplet diameter below 100 nm and a small negative surface charge. The system was stable without alteration of mean droplet diameter for three months. Then, the ASX-NE was functionalised with carboxymethyl chitosan (CMCS) through direct CMCS (0.02%) incorporation during the preparation process. The ASX chemical stability and skin permeability increased in the following order: ASX solution control < ASX-NE < CMCS-ASX-NE. Cell viability assays on L929 cells revealed low cytotoxicity of blank NE, ASX-NE and CMCS-ASX-NE in the range from 5 to 500 μg mL^-1. In conclusion, the CMCS-ASX-NE might be a promising delivery vehicle in dermal and transdermal products.