Transdermal Cubic Phases of Metformin Hydrochloride: In Silico and in Vitro Studies of Delivery Mechanisms

Rapid Correction of the Hypoglycemia State in Nonhuman Primates Using a Glucagon Long-Dissolving Microneedle Patch

The timely administration of glucagon is a standard clinical practice for the treatment of severe hypoglycemia. However, the process involves cumbersome steps, including the reconstitution of labile glucagon and filling of the syringe, which cause considerable delays in emergency situations. Moreover, multiple dosages are often required to prevent the recurrence of the hypoglycemic episode because of the short half-life of glucagon in plasma. Herein, we develop a glucagon-loaded long-dissolving microneedle (GLMN) patch that exhibits the properties of fast onset and sustained activity for the effective treatment of severe hypoglycemia. Three types of MN patches were fabricated with different dimensions (long, medium, and short). The longer MN patch packaged a higher dosage of glucagon and exhibited supreme mechanical strength compared to the shorter one. Additionally, the longer MN patch could insert more deeply into the skin, resulting in higher permeability of glucagon across the skin tissue and more rapid systemic absorption as compared with the shorter MN patch. The GLMN patch was observed to reverse the effects of hypoglycemia within 15 min of application in animal models (specifically, rat and rhesus monkey models) and maintained long-term glycemic control, owing to highly efficient drug permeation and the drug reservoir effect of the MN base. The current study presents a promising strategy for the rapid reversal of severe hypoglycemia that exhibits the desirable properties of easy use, high efficiency, and sustained action.

Separable Microneedle for Integrated Hyperglycemia Sensing and Photothermal Responsive Metformin Release

Microdevices that offer hyperglycemia monitoring and controllable drug delivery are urgently needed for daily diabetes management. Herein, a theranostic separable double-layer microneedle (DLMN) patch consisting of a swellable GelMA supporting base layer for glycemia sensing and a phase-change material (PCM) arrowhead layer for hyperglycemia regulation has been fabricated. The Cu-TCPP(Fe)/glucose oxidase composite and 3,3',5,5'-tetramethylbenzidine coembedded in the supporting base layer permit a visible color shift at the base surface in the presence of glucose via a cascade reaction, allowing for the in situ detection of glucose in interstitial fluid. The PCM arrowhead layer is encapsulated with water monodispersity melanin nanoparticles from Sepia officinalis and metformin that is imparted with a near-infrared ray photothermal response feature, which is beneficial to the controllable release of metformin for suppression of hyperglycemia. By applying the DLMN patch to the streptozotocin-induced type 2 diabetic Sprague-Dawley rat model, the results demonstrated that it can effectively extract dermal interstitial fluid, read out glucose levels, and regulate hyperglycemia. This DLMN-integrated portable colorimetric sensor and self-regulated glucose level hold great promise for daily diabetes management.

Monoolein-based nanodispersions for cutaneous co-delivery of methylene blue and metformin: Thermal and structural characterization and effects on the cutaneous barrier, skin penetration and cytotoxicity

This study evaluated the potential of monoolein (MO)-based nanodispersions to promote the cutaneous co-delivery of metformin (MET) and methylene blue (MB) for the treatment of non-melanoma skin cancer. MO-based nanodispersions were obtained using Kolliphor® P407 (KP) and/or sodium cholate (CH), and characterized concerning the structure, thermal stability, ability to disrupt the skin barrier, cutaneous permeation and retention of MB and MET. Additionally, the cytotoxic effect of MO nanodispersions-mediated combination therapy using MET and MB in A431 cells was evaluated. The nanodispersions exhibited nanometric size (<200 nm) and thermal and physical stability. Small angle X-ray scattering studies revealed multiple structures depending on composition. They were able to interact with stratum corneum lipid structure, increasing its fluidity. The effect of MO-nanodispersions on topical/transdermal delivery of MB and MET was composition-dependent. Nanodispersions with low MO content (5 %) and stabilized with KP and CH (0.05-0.10 %) were the most promising, enhancing the cutaneous delivery of MB and MET by 1.9 to 2.2-fold and 1.4 to 1.7-fold, respectively, compared to control. Cytotoxic studies revealed that the most promising MO nanodispersion-mediated combination therapy using MET and MB (1:1) reduced the IC₅₀ by 24-fold, compared to MB solution, and a further reduction (1.5-fold) was observed by MB photoactivation.

Efficacy and safety of permeation enhancers: a kinetic evaluation approach and molecular mechanism study in the skin

This study sought to provide approach for evaluating and predicting the efficacy and safety of permeation enhancers on the basis of their kinetic distribution behavior in the skin dictated by physicochemical properties. Herein, the efficacy-safety regularity of eight permeation enhancers were studied with ex vivo skin permeation study, small-angle X-ray scattering, MTT assay, H&E staining, and in vivo skin erythema analysis, classifying into the following three categories: high enhancement-low irritation, medium enhancement-high irritation, and low enhancement-low irritation. These three modes were positively correlated with the distribution amount of permeation enhancers in the skin layers and verified by the in vitro tape-stripping study. The kinetic parameter, effective-safety index (I_ES), was proposed to describe the regularity of enhancement effect tendency and irritation risk, and the relationship between I_ES and physicochemical properties of permeation enhancers was analyzed with multiple regression analysis. According to the results of modulated temperature differential scanning calorimetry and dielectric spectrum, permeation enhancers with high lipophilicity and low polarity had I_ES > 1, suggesting high enhancement effect and low irritation due to their higher affinity with the stratum corneum (SC) than with epidermis (EP). Permeation enhancers with medium lipophilicity and medium polarity exhibited 0 <I_ES ≤ 1, showing medium enhancement effect and high irritation, as determined by their comparable affinity with the SC and epidermis (EP). However, permeation enhancers with low lipophilicity and high polarity had I_ES → 0, demonstrating low enhancement effect and irritation, as indicated by their poor affinity with the SC. In summary, different physicochemical properties of permeation enhancers influenced their affinities with skin layers, resulting in their different enhancement effect and irritation potential. This study will provide a theoretical basis and criteria for evaluating and predicting the safety and efficacy of permeation enhancers, which will enable a more rational selection of permeation enhancers in the optimization of transdermal patches.

Recent advances in versatile inverse lyotropic liquid crystals

Owing to the rapid and significant progress in advanced materials and life sciences, nanotechnology is increasingly gaining in popularity. Among numerous bio-mimicking carriers, inverse lyotropic liquid crystals are known for their unique properties. These carriers make accommodation of molecules with varied characteristics achievable due to their complicated topologies. Besides, versatile symmetries of inverse LCNPs (lyotropic crystalline nanoparticles) and their aggregating bulk phases allow them to be applied in a wide range of fields including drug delivery, food, cosmetics, material sciences etc. In this review, in-depth summary, discussion and outlook for inverse lyotropic liquid crystals are provided.

Hydrogels and Cubic Liquid Crystals for Non-Invasive Sampling of Low-Molecular-Weight Biomarkers-An Explorative In Vivo Study

The molecular composition of human skin is altered due to diseases, which can be utilized for non-invasive sampling of biomarkers and disease diagnostics. For this to succeed, it is crucial to identify a sampling formulation with high extraction efficiency and reproducibility. Highly hydrated skin is expected to be optimal for increased diffusion of low-molecular-weight biomarkers, enabling efficient extraction as well as enhanced reproducibility as full hydration represents a well-defined endpoint. Here, the aim was to explore water-based formulations with high water activities, ensuring satisfactory skin hydration, for non-invasive sampling of four analytes that may serve as potential biomarkers, namely tryptophan, tyrosine, phenylalanine, and kynurenine. The included formulations consisted of two hydrogels (chitosan and agarose) and two different liquid crystalline cubic phases based on the polar lipid glycerol monooleate, which were all topically applied for 2 h on 35 healthy subjects in vivo. The skin status of all sampling sites was assessed by electrical impedance spectroscopy and transepidermal water loss, enabling explorative correlations between biophysical properties and analyte abundancies. Taken together, all formulations resulted in the successful and reproducible collection of the investigated biomarkers. Still, the cubic phases had an extraction capacity that was approximately two times higher compared to the hydrogels.

Sustainable and efficient skin absorption behaviour of transdermal drug: The effect of the release kinetics of permeation enhancer

At present, how the release kinetics of permeation enhancers affected their enhancement efficacy on drug skin absorption and its molecular mechanisms remained unclear. Herein, the release kinetics of permeation enhancer (Plurol Oleique CC (POCC)) which involved release percent (PR), release duration (RD) and release kinetic constant (k) and its enhancement efficacy on drug skin absorption were investigated with in vitro skin retention study and in vitro skin permeation study, respectively. POCC released from the acidic-drug loading patches followed with the Higuchi release model and had short RD (8-16 h), resulting in its unsustainable enhancement efficiency for acidic drugs. However, POCC released from the basic-drug loading patches followed with zero-order model with long RD (12-24 h), inducing a sustainable and efficient enhancement efficiency for basic drugs. The lower variance of an innovative parameter permeation enhancement coefficient (C_PE) represented the relatively sustainable and effective enhancement effect and was listed as followed: 0.20 (Zaltoprofen (ZPF)), 0.31 (Diclofenac (DCF)), 0.27 (Indomethacin (IMC)), 0.07 (Azasetron (AST)), 0.11 (Oxybutynin (OBN)) and 0.06 (Donepezil (DNP)). According to the results of FT-IR, MTDSC, ¹³C NMR spectra, molecular dynamics simulation, SAXS and Raman imaging, the Higuchi release model was caused by strong interaction between the acid drugs and pressure sensitive adhesive (PSA). This strong interaction induced faster diffusion speed of POCC from acidic-drug loading patches and make the swell degree of long periodicity phase (LPP) of stratum corneum (SC) lipids reached plateau early. The zero-order release model was because the weak interaction between basic drugs and PSA making most of POCC was still bound to PSA, which in turn lead to LPP swelled at a slow but sustainable process. In conclusion, zero-order release kinetic of POCC lead to sustainable and efficient penetration enhancement efficiency on basic drug, while the Higuchi release kinetic showed opposite effect for acidic drugs. A deep understanding of release kinetics of enhancer and its enhancement efficiency may drive the ideal selection of permeation enhancers and rational optimization of transdermal patches.

Lyotropic liquid crystal-based transcutaneous peptide delivery system: Evaluation of skin permeability and potential for transcutaneous vaccination

Transcutaneous drug delivery is a promising method in terms of drug repositioning and reformulation because of its non-invasive and easy-to-use features. To overcome the skin barrier, which is the biggest challenge in transcutaneous drug delivery, a number of techniques, such as microemulsion, solid-in-oil dispersions and liposomes, have been studied extensively. However, the low viscosity of these formulations limits drug retention on the skin and reduces patient acceptability. Although viscosity can be increased by adding a thickening reagent, such an addition often alters formulation nanostructures and drug solubility, and importantly, decreases skin permeability. In this study, a gel-like lyotropic liquid crystal (LLC) was used as a tool to enhance skin permeability. In particular, we prepared 1-monolinolein (ML)-based LLCs with different water contents. All LLCs significantly enhanced skin permeation of a peptide drug, an epitope peptide of melanoma, despite their high viscoelasticity. Fourier transform infra-red spectroscopic analysis of the skin surface treated with the LLCs revealed that the gyroid geometry more strongly interacted with the lamellar structure inside the stratum corneum (SC) than the diamond geometry. Finally, as the result of the in vivo tumor challenge experiment using B16F10 melanoma-bearing mice, the LLC with the gyroid geometry showed stronger vaccine effect against tumor than a subcutaneous injection. Collectively, ML-based LLCs, especially with the gyroid geometry, are a promising strategy to deliver biomacromolecules into skin. STATEMENT OF SIGNIFICANCE: Transcutaneous drug delivery is a promising method for drug repositioning and reformulation because of its non-invasive and easy-to-use features. To overcome the skin barrier, which is the biggest challenge in transcutaneous drug delivery, we used a gel-like lyotropic liquid crystal (LLC) as a novel tool to enhance skin permeability. In this paper, we demonstrated that an LLC with a specific liquid crystalline structure has the highest skin permeation enhancement effect for a peptide antigen as a model drug. Moreover, the peptide antigen-loaded LLC showed a vaccine effect that was comparable to a subcutaneous injection in vivo. This study provides a basis for designing a transcutaneous delivery system of peptide drugs with LLC.

Cubosomes as an emerging platform for drug delivery: a state-of-the-art review

Lipid-based drug delivery nanoparticles, including non-lamellar type, mesophasic nanostructured materials of lyotropic liquid crystals (LLCs), have been a topic of interest for researchers for their applications in encapsulation of drugs...

Design of Swollen Lipidic Cubic Phase to Increase Transcutaneous Penetration of Biomacromolecules

Lipidic cubic phase (LCP) is a self-assembled system composed of lipids with interpenetrated aqueous channels, and its potential in drug delivery systems has been investigated. Although LCP was shown to improve transcutaneous penetration of hydrophilic molecules of up to 1203 Da so far, the transcutaneous delivery of larger molecules such as proteins has not been achieved. This is likely because proteins are usually larger than the aqueous channels of LCP (∼37.2 Å in diameter), which limits the molecular diffusion in LCP. In this report, we overcome this issue by adding N-octyl-β-d-glucopyranoside to glyceryl monooleate-water-based LCP to give swollen LCP (SLCP), which has larger aqueous channel diameters (∼65.6 Å). First, we systemically evaluated the effect of swelling on drug diffusion in LCP/SLCP. The release kinetics of various peptides and proteins whose sizes ranged from 9.14 to 55.28 Å in diameter were evaluated, and the diffusion coefficients (D) were calculated by the Fickian diffusion model. As expected, all peptides and proteins diffused faster in SLCP than in LCP. A more detailed analysis revealed a negative linear relationship between log D and the ratio of the radius of gyration of the proteins to the aqueous channel radius, indicating that swelling of a cubic nanostructure is an effective strategy to enhance D. Next, the skin penetration of proteins encapsulated in LCP and SLCP was evaluated. The skin penetration of ovalbumin (42.9 kDa), for example, was enhanced by SLCP but not by LCP, and a positive correlation between D and the amount of skin penetration was found. Collectively, this study provides an effective measure for designing LCP systems that enhance transcutaneous penetration of biomacromolecules.

Ocular lamellar crystalline gels for sustained release and enhanced permeation of resveratrol against corneal neovascularization

Corneal neovascularization (CNV) is the major cause of blindness after eye injury; however, only several drugs can be applied and the invasive administration ways (i.e., intravitreal injection and subconjunctival injection) are used. Resveratrol is a highly effective anti-VEGF agent against CNV. However, its applications are limited due to its strong hydrophobicity and instability. Here, we developed a resveratrol-loaded ocular lamellar crystalline gel (ROLG) for high inhibition of CNV. ROLGs were composed of resveratrol, glyceryl monooleate (GMO), ethanol, and water, and their lamellar crystalline structures were identified by polarizing light microscopy and small-angle X-ray scattering. High drug loading (4.4 mg/g) of ROLGs was achieved due to the hydrogen bonding between GMO and resveratrol. Resveratrol showed sustained release with 67% accumulative release in 7 h, which was attributed to the slow erosion of gels. Resveratrol in ROLGs had a high corneal permeation 3 times higher than resveratrol in hyaluronic acid suspensions (RHSs). ROLGs were administered to rats only once a day because of their strong retention on the cornea surface. ROLGs were safe due to the very little contact of ethanol in ROLGs to the cornea. CNV post-rat corneal alkaline injury was highly inhibited by ROLGs, resulting from the attenuation of corneal VEGF expression and then corneal healing was improved. The ROLG was a promising ocular medicine for the prevention of CNV.

Topical transdermal chemoprevention of breast cancer: where will nanomedical approaches deliver us?

Despite the high incidence of breast cancer, there are few pharmacological prevention strategies for the high-risk population and those that are available have low adherence. Strategies that deliver drugs directly to the breasts may increase drug local concentrations, improving efficacy, safety and acceptance. The skin of the breast has been proposed as an administration route for local transdermal therapy, which may improve drug levels in the mammary tissue, due to both deep local penetration and percutaneous absorption. In this review, we discuss the application of nanotechnology-based strategies for the delivery of well established and new agents as well as drug repurposing using the topical transdermal route to improve the outcomes of preventive therapy for breast cancer.

Effect of Chemical Penetration Enhancer-Adhesive Interaction on Drug Release from Transdermal Patch: Mechanism Study Based on FT-IR Spectroscopy, 13C NMR Spectroscopy, and Molecular Simulation

Chemical penetration enhancers (CPEs) are commonly added into transdermal patches to impart improved skin permeation of drug. However, significant unexplained variability in drug release kinetics in transdermal patches is possible as a result of the addition of CPEs; investigations into the underlying mechanisms are still limited. In the present study, a diverse set of CPEs was employed to draw broad conclusions. Solubility parameters of CPEs and acrylate pressure-sensitive adhesive were calculated by molecular dynamics simulation and Fedors group contribution method to evaluate drug-adhesive miscibility. CPE-adhesive interaction was characterized by FT-IR study, ¹³C NMR spectroscopy, and molecular docking simulation. Results showed that release enhancement ratio (ER_R) of CPEs for zolmitriptan was rank ordered as isopropyl myristate > azone > Plurol Oleique^® CC497 > Span^® 80 > N-methylpyrrolidone > Transcutol^® P. It was found that solubility parameter difference (Δδ) between CPE and adhesive was negatively related with ER_R. It was proved that hydrogen bonding between CPE and adhesive would increase drug release rate, but only if the CPE showed good miscibility with adhesive. CPE like isopropyl myristate, which had good miscibility with adhesive, could decrease drug-adhesive interaction leading to the release of drug from adhesive.

The impact of chemical engineering and technological advances on managing diabetes: present and future concepts

Monitoring blood glucose levels for diabetic patients is critical to achieve tight glycaemic control. As none of the current antidiabetic treatments restore lost functional β-cell mass in diabetic patients, insulin injections and the use of insulin pumps are most widely used in the management of glycaemia. The use of advanced and intelligent chemical engineering, together with the incorporation of micro- and nanotechnological-based processes have lately revolutionized diabetic management. The start of this concept goes back to 1974 with the description of an electrode that repeatedly measures the level of blood glucose and triggers insulin release from an infusion pump to enter the blood stream from a small reservoir upon need. Next to the insulin pumps, other drug delivery routes, including nasal, transdermal and buccal, are currently investigated. These processes necessitate competences from chemists, engineers-alike and innovative views of pharmacologists and diabetologists. Engineered micro and nanostructures hold a unique potential when it comes to drug delivery applications required for the treatment of diabetic patients. As the technical aspects of chemistry, biology and informatics on medicine are expanding fast, time has come to step back and to evaluate the impact of technology-driven chemistry on diabetics and how the bridges from research laboratories to market products are established. In this review, the large variety of therapeutic approaches proposed in the last five years for diabetic patients are discussed in an applied context. A survey of the state of the art of closed-loop insulin delivery strategies in response to blood glucose level fluctuation is provided together with insights into the emerging key technologies for diagnosis and drug development. Chemical engineering strategies centered on preserving and regenerating functional pancreatic β-cell mass are evoked in addition as they represent a permanent solution for diabetic patients.

Additives-directed lyotropic liquid crystals architecture: Simulations and experiments

In this study, alkanes and sucrose esters are employed to investigate the influence of additives on lyotropic liquid crystal architecture. After molecular dynamic simulations and experiment characterization, we showed how the additives control the structure of LLCs. By controlling the polarity of additives, the phase behavior of LLCs can be engineered to form the required structure. Dissipative particle dynamics (DPD) is introduced for simulating the self-assembly of phytantriol (PT), providing intuitionistic images and structure information, which shows that additives with low-polarity complicate the internal structure of liquid crystal systems. Then the ternary phase diagrams of additives, PT, and water are constructed to systematically study the effects of additives on the phase behavior of LLCs. Consistent with DPD simulation results, there is a certain regularity in the effects of additives on the structure of liquid crystals. The difference in the structure of LLCs is due to the variability in the critical packing parameter (CPP) obtained by changing the polarity of additives. Our findings demonstrate that additives polarity is a key factor in LLCs structure, and may pave a promising avenue for novel LLCs development and translation, determining the self-assembly process and the resulting phase of LLCs.

Developing an analytical method by HPLC for simultaneous quantification of methylene blue and metformin applied to in vitro skin permeation and retention studies

The aim of this study was to develop an HPLC method for simultaneous quantification of metformin (MET) and methylene blue (MB) in in vitro skin permeation/retention studies, in which retention was evaluated in the different layers of the skin [stratum corneum (SC) and the viable epidermis + dermis (VE + D)]. The method was validated considering the following parameters: specificity, linearity, quantitation limit (LOQ), recovery, precision and accuracy. Calibration curves were obtained using the following six matrices: methanol, water, methanolic extracts from the SC and VE + D spiked with the drugs and drugs extracted from the SC and VE + D. The precision, accuracy and LOQ of the method were evaluated in water and in VE + D and SC, applying the drug extraction process. The results show that the method is selective and linear for both drugs. The precision and accuracy values, independent of matrix and drug, were below the limit of 15%. The LOQ of MB was defined as 0.4 μg/ml in the VE + D and SC and 0.8 μg/ml in water. The LOQ of MET was defined as 0.8 μg/ml in the VE + D and SC and 0.4 μg/ml in the water. The recovery of the method was adequate, consistent and reproducible for the concentration range of 0.4-10 μg/ml for MB (73.3-92.1%) and 0.8-10.0 μg/mL for MET (72.4-94.4%). This method has a potential application in the development of formulation for skin delivery of MB and MET.

Preparation and Evaluation of Cubic Nanoparticles for Improved Transdermal Delivery of Propranolol Hydrochloride

Transdermal drug delivery of propranolol hydrochloride (PRH) is promising for the treatment of infantile hemangioma (IH). Clinically used PRH hydrogel fails to reach the deep IH for complete recovery. In this study, the PRH-loaded cubic nanoparticles (CNPs) were prepared to promote the transdermal effect of PRH. A remote drug loading method was developed to prepare the PRH-CNPs. For the traditional passive drug loading method, the largest encapsulation efficiency (EE%) was around 50%. The remote drug loading was performed by increasing the pH of the mixture of blank CNPs and PRH solution. The optimal PRH-CNPs showed an EE% of 90.15 ± 2.44% at pH 8.5. The permeation of the PRH solution was poor while the PRH-CNPs showed greatly enhanced skin permeation. It was found that smaller-sized PRH-CNPs contributed to increased skin permeation and retention. In addition, the PRH-CNPs had higher cytotoxicity towards the EOMA cells when compared with the PRH solution. During storage for 1 month, the PRH-CNPs kept stable size distribution, pH, and EE%. In conclusion, results of this study suggested that the PRH-CNPs could be a potential candidate for the treatment of the IH by transdermal delivery.

Amifostine-loaded armored dissolving microneedles for long-term prevention of ionizing radiation-induced injury

Amifostine is a cytoprotective agent against the hematopoietic damage induced by ionizing radiation, although the intravenous injection of amifostine is a unique administration method with strict dosing time limitation. Hence, the fields of application of amifostine are greatly limited. Here, we developed an amifostine-loaded armored microneedle (AAMN) with long-term prevention of hematopoietic injury induced by ionizing radiation. First, amifostine-loaded hyaluronic acid microneedles (AMNs) were fabricated, and the AMNs were then dipped in an N-vinyl-2-pyrrolidone (NVP) solution followed by ultraviolet (UV) photocuring to obtain AAMNs. AAMNs were nail-shaped with much higher mechanical strength compared to the conical shape and weak strength of AMNs, which was verified by their in silico simulation. In the in vitro release experiment, more than 55% of amifostine was released from AAMNs within 10 min, and 95% was released in 60 min. Drug skin permeation of AAMNs was also high, at twice that of AMNs. AAMNs provided long-term protection of the hematopoietic system from radiation within 3-7 h pre-radiation compared to the unique amifostine injection 0.5 h pre-radiation because topical application of AAMNs led to the long-term maintenance of the in vivo effective drug concentration. More importantly, AAMNs led to the survival of all irradiated mice due to intravenous amifostine. AAMNs are a promising transdermal delivery system of amifostine for long-term protection against ionizing radiation-induced injury. STATEMENT OF SIGNIFICANCE: An amifostine-loaded dissolving armored microneedle (AAMN) patch is developed for long-term prevention of ionizing radiation-induced injury. High drug loads in microneedles (MNs) with adequate mechanical strength is a challenge. We fabricated armors on the surface of high amifostine-loaded hyaluronic acid microneedles (AMNs) by dipping the tips of AMNs in N-vinyl-2-pyrrolidone (NVP) solutions and then subjecting them to UV irradiation, and high-strength armored AMNs (AAMNs) were obtained. AAMNs show deeper skin insertion and much higher drug permeation than AMNs. The controlled drug release from AAMNs in the mouse skins provides a long-term protection of radiation-induced injury with 3-7 h administration pre-radiation compared to the merely 0.5-h point of amifostine injection.

Wound healing of laser injured skin with glycerol monooleicate cubic liquid crystal

Laser has found increasingly wider applications in the medical filed, but laser is likely to cause damage to patients' skin. In this experiment, we were surprised to find that glyceryl monooleate (GMO)-based cubic liquid crystal had excellent healing effect on the skin of guinea pigs damaged by laser. Transepidermal water loss (TEWL), H.E. pathology, Masson trichrome dyeing, interleukin-6 (IL-6) levels and the percutaneous depth of fluorescein isothiocyanate (FITC) dyeing were used to evaluate the therapeutic effect of GMO-based cubic liquid crystals against laser damage of different degrees among guinea pigs. GMO-based cubic liquid crystals had an obvious effect in the treatment of slight and moderate laser damage. This finding may provide a effective medical treatment protocols for laser skin damage.

Near-infrared light activatable hydrogels for metformin delivery

Drug loaded hydrogels have proven to be versatile controlled-release systems. We report here on heat active hydrogel formation by mixing graphene oxide (GO) or carboxyl enriched reduced graphene oxide (rGO-COOH) with metformin hydrochloride, an insulin sensitizer drug currently used as the first line therapy to treat patients with type 2 diabetes. The driving forces of the gelation process between the graphene-based nanomaterial and metformin are hydrogen bonding and electrostatic interactions, weakened at elevated temperature. Using the excellent photothermal properties of the graphene matrixes, we demonstrate that these supramolecular drug reservoirs can be photothermally activated for transdermal metformin delivery. A sustained delivery of metformin was achieved using a laser power of 1 W cm-2. In vitro assessment of the key target Glucose-6 Phosphatase (G6P) gene expression using a human hepatocyte model confirmed that metformin activity was unaffected by photothermal activation. In vivo, metformin was detected in mice plasma at 1 h post-activation of the metformin loaded rGO-COOH gel.

Transdermal metformin hydrochloride-loaded cubic phases: in silico formulation optimization, preparation, properties, and application for local treatment of melanoma

Metformin hydrochloride (Met) is commonly used for antidiabetic therapy though its antimelanoma action is also reported. Conventional oral administration method of Met is not appropriate for therapy of melanoma because of large dose, adverse reactions, and low efficiency. Here, a transdermal Met-loaded cubic phase was developed for local treatment of melanoma. In silico formulation optimization of the cubic phases was done, and the corresponding formulations were prepared and characterized. The optimized formulations were screened based on the stable microstructure and proper fluidity. Highly efficient mouse skin permeability of Met was found with the cubic phases compared to Met solutions. High antimelanoma effect of transdermal Met-loaded cubic phases also was shown by the significant decrease of tumor volume and the improvement of melanoma cell apoptosis on the B16 melanoma mice. Met-loaded cubic phases are a promising topically applied medication for local therapies of melanoma.