Innovative transdermal delivery of insulin using gelatin methacrylate-based microneedle patches in mice and mini-pigs.

Painless and controlled on-demand drug delivery is the ultimate goal for the management of various chronic diseases, including diabetes. To achieve this purpose, microneedle patches are gaining increased attention. While degradable microneedle (MN) arrays are widely employed, the use of non-dissolving MN patches remains a challenge to overcome. In this study, we demonstrate that crosslinking gelatin methacrylate with polyethylene glycol diacrylate (PEGDA) is potent for engineering non-dissolving MN arrays. Incorporation of MoS2 nanosheets as a photothermal component into MN hydrogels results in MNs featuring on-demand release properties. An optimized MoS2-MN array patch formed using a hydrogel solution containing 500 µg mL-1 of MoS2 and photochemically crosslinked for 5 min shows required mechanical behavior under a normal compressive load to penetrate the stratum corneum of mice or pig skin and allows the delivery of macromolecular therapeutics such as insulin upon swelling. Using ex vivo and in vivo models, we show that the MoS2-MN patches can be used for loading and releasing insulin for therapeutic purposes. Indeed, transdermal administration of insulin loaded into MoS2-MN patches reduces blood glucose levels in C57BL/6 mice and mini-pigs comparably to subcutaneously injected insulin. We believe that this on-demand delivery system might alter the current insulin therapies and might be a potential approach for delivery of other proteins.

Development of a multiparametric (bio)sensing platform for continuous monitoring of stress metabolites.

There is a growing need for real-time monitoring of metabolic products that could reflect cell damages over extended periods. In this paper, we report the design and development of an original multiparametric (bio)sensing platform that is tailored for the real-time monitoring of cell metabolites derived from cell cultures. Most attractive features of our developed electrochemical (bio)sensing platform are its easy manufacturing process, that enables seamless scale-up, modular and versatile approach, and low cost. In addition, the developed platform allows a multiparametric analysis instead of single-analyte analysis. Here we provide an overview of the sensors-based analysis of four main factors that can indicate a possible cell deterioration problem during cell-culture: pH, hydrogen peroxide, nitric oxide/nitrite and lactate. Herein, we are proposing a sensors platform based on thick-film coupled to microfluidic technology that can be integrated into any microfluidic system using Luer-lock connectors. This platform allows obtaining an accurate analysis of the secreting stress metabolites during cell/tissues culture.

Reference method for off-line analysis of nitrogen oxides in cell culture media by an ozone-based chemiluminescence detector.

Nitric oxide (NO) and its by-products are important biological signals in human physiology and pathology particularly in the vascular and immune systems. Thus, in situ determination of the NO-related molecule (NOx) levels using embedded sensors is of high importance particularly in the context of cellular biocompatibility testing. However, NOx analytical reference method dedicated to the evaluation of biomaterial biocompatibility testing is lacking. Herein, we demonstrate a PAPA-NONOate-based reference method for the calibration of NOx sensors. After, the validation of this reference method and its potentialities were demonstrated for the detection of the oxidative stress-related NO secretion of vascular endothelial cells in a 3D tissue issued from 3D printing. Such NOx detection method can be an integral part of cell response to biomaterials. Graphical abstract.

Introduction of a model of skin lesions on rats and testing of dissolving microneedles containing 5-aminolevulinic acid.

Topical photodynamic therapy (PDT) is widely used to treat non melanoma skin cancers. It consists of topically applying on the skin lesions a cream containing a prodrug (5-aminolevulinic acid (5-ALA) or methyl aminolevulinate (MAL)) that is then metabolized to the photosensitizer protoporphyrin IX (PpIX). Light irradiation at PpIX excitation wavelength combined with oxygen then lead to a photochemical reaction inducing cell death. Nevertheless, this conventional PDT treatment is currently restricted to superficial skin lesions since the penetration depth of the prodrug is limited and hampers the production of PpIX in deep seated lesions. To overcome this problem, dissolving microneedles (MNs) included in a square flexible patch were developed. This easy-to-handle MN-patch is composed of 5-ALA mixed with hyaluronic acid (HA) and has the ability to dissolve after skin application. To evaluate the efficiency of this MN-patch in vivo, a skin lesion model has been developed on rats by applying UV-B illuminations. After 40 UV-B illuminations, histological and pharmacokinetic controls confirmed that the rats presented skin lesions. Once the rat skin lesion model has been validated, it was demonstrated that the MNs penetrated into the skin and fully dissolved in one hour on most of the rats. After one hour, the fluorescence images showed that the MN-patch produced a consequent and homogeneous level of PpIX. Overall, the dissolving MN-patch is a recent technology that has interesting features and several preclinical investigations should be led to compare its efficiency to that of the conventional treatment for PDT of non melanoma skin cancers.

A facile fabrication of dissolving microneedles containing 5-aminolevulinic acid.

Photodynamic therapy induced by protoporphyrin IX (PpIX) is widely used to treat precancerous skin lesions. The penetration depth of the prodrug 5-aminolevulinic acid (5-ALA) using topical application is currently limited, which hampers the production of PpIX in deep seated lesions. To enhance 5-ALA delivery in deep skin layers, a soluble microneedles patch (MN-patch) containing 5-ALA has been successfully developed by using a fast solvent casting molding method which could be easily up-scaled. The shape, number and height of the needles have been designed according to the medical application and the mechanical strain necessary for skin insertion. Hyaluronic acid (HA) has been chosen as the needle materials due to its biocompatibility, fast solubility and biodegradation and was mixed with 5-ALA prior to casting. HA-based MN-patch containing 5-ALA have exhibited mechanical properties enabling a good insertion into the skin without significant damages to MN. Interactions between HA and 5-ALA were evaluated by Fourier transform infrared spectroscopy (FTIR) and carbon nuclear magnetic resonance (13C NMR), stability of 5-ALA in the MN-patch was monitored by proton nuclear magnetic resonance (1H NMR) and exhibited a good stability over 5 months after manufacturing. Dissolution rate of the whole patch was completed in 1 hour in ex vivo rat skin without cytotoxicity. Overall, the MN-patch can be a promising technique to enhance 5-ALA penetration and produce PpIX in deeper skin lesions.

Photodynamic therapy for skin cancer: How to enhance drug penetration?

Photodynamic therapy (PDT) induced by protoporphyrin IX (PpIX) has been widely used in dermatological practices such as treatment of skin cancers. Clearance rate depends on different factors such as light irradiation, skin oxygenation and drug penetration. The poor penetration of 5-aminolevulinic acid (5-ALA) with topical application is limited and restrains the production of PpIX which could restrict PDT outcomes. This review will focus on techniques already used to enhance drug penetration in human skin, and will present their results, advantages, and drawbacks. Chemical and physical pretreatments will be discussed. Chemical pre-treatments comprise of drug formulation modification, use of agents that modify the heme cycle, enhance PpIX formation, and the combination of differentiation-promoting agent prior to PDT. On the other hand, physical pretreatments affect the skin barrier by creating holes in the skin or by removing stratum corneum. To promote drug penetration, iontophoresis and temperature modulation are interesting alternative methods. Cellular mechanisms enrolled during chemical or physical pretreatments have been investigated in order to understand how 5-ALA penetrates the skin, why it is preferentially metabolized in PpIX in tumour cells, and how it could be accumulated in deeper skin layers. The objective of this review is to compare clinical trials that use innovative technology to conventional PDT treatment. Most of these pretreatments present good or even better clinical outcomes than usual PDT.

Electrospinning in water and in situ crosslinking of hyaluronic acid / cyclodextrin nanofibers: Towards wound dressing with controlled drug release.

Hyaluronic acid (HA) is widely investigated due to its high potential for wound dressing applications. The fabrication of biomimetic HA-based scaffolds by electrospinning is thus extensively studied. However, HA is often dissolved in toxic organic solvents to allow the efficient production of electrospun nanofibers. Indeed, although HA is soluble in water, its ionic nature leading to long-range electrostatic interactions and the presence of counter ions induce a dramatic increase of the viscosity of aqueous HA solutions without insuring enough chain entanglements necessary for a stable and efficient electrospinning. In this study, biocompatible insoluble HA-based nanofibers were fabricated by electrospinning in pure water. To this end, poly(vinyl alcohol) (PVA) was added as a carrier polymer and it was found that the addition of hydroxypropyl-ßcyclodextrin (HPßCD) stabilized the process of electrospinning and led to the efficient formation of uniform nanofibrous scaffolds. An in situ crosslinking process of the scaffolds is also proposed, insuring a whole fabrication process without any toxicity. Furthermore, the beneficial presence of HPßCD in the HA-based scaffolds paves the way for wound dressing applications with controlled drug encapsulation-release properties. As a proof of concept, naproxen (NAP), a non-steroidal anti-inflammatory drug was chosen as a model drug. NAP was impregnated into the scaffolds either in aqueous solution or under supercritical CO2. The resulting functional scaffolds showed a regular drug release profile along several days without losing the fibrous structure. This study proposes a simple approach to form stable HA-based nanofibrous scaffolds embedding HPßCD using water as the only solvent, enabling the development of safe functional wound dressings.