Fabrication of photomasks consisting microlenses for the production of polymeric microneedle array

Continuous High-Throughput Fabrication of Architected Micromaterials via In-Air Photopolymerization

Recent advances in optical coding, drug delivery, diagnostics, tissue engineering, shear-induced gelation, and functionally engineered rheology crucially depend on microparticles and microfibers with tunable shape, size, and composition. However, scalable manufacturing of the required complex micromaterials remains a long-standing challenge. Here in-air polymerization of liquid jets is demonstrated as a novel platform to produce microparticles and microfibers with tunable size, shape, and composition at high throughput (>100 mL h-1 per nozzle). The polymerization kinetics is quantitatively investigated and modeled as a function of the ink composition, the UV light intensity, and the velocity of the liquid jet, enabling engineering of complex micromaterials in jetting regimes. The size, morphology, and local chemistry of micromaterials are independently controlled, as highlighted by producing micromaterials using 5 different photopolymers as well as multi-material composites. Simultaneous optimization of these control parameters yields rapid fabrication of stimuli-responsive Janus fibers that function as soft actuators. Finally, in-air photopolymerization enables control over the curvature of printed droplets, as highlighted by high-throughput printing of microlenses with tunable focal distance. The combination of rapid processing and tunability in composition and architecture opens a new route toward applications of tailored micromaterials in soft matter, medicine, pharmacy, and optics.

Rapid microneedle fabrication by heating and photolithography

Many fabrication methods for microneedle (MN) involve harsh conditions and long drying time. This study aims to fabricate a dissolving MN patch in a simple and efficient manner under mild conditions, using a combination of thermal and photo polymerisation. The MN patch was fabricated by pre-polymerisation of vinylpyrrolidone solution with heating followed by photolithography. The heating temperature and time of pre-polymer solution curing were optimized based on viscosity measurement. The MN properties including shape, size, skin penetration, dissolution, moisture absorption were determined. The fabricated MNs were sharp and consistent. The heated N-vinylpyrrolidone solution required less UV exposure time, thus reducing the total fabrication time. The percentage of MN penetration in human cadaver skin was more than 33.9%. The MN was dissolved within 1-2 min in water, or 40 min in saturated water vapor.

Oleic Acid Nanovesicles of Minoxidil for Enhanced Follicular Delivery

Current topical minoxidil (MXD) formulations involve an unpleasant organic solvent which causes patient incompliance in addition to side effects in some cases. Therefore, the objective of this work was to develop an MXD formulation providing enhanced follicular delivery and reduced side effects. Oleic acid, being a safer material, was utilized to prepare the nanovesicles, which were characterized for size, entrapment efficiency, polydispersity index (PDI), zeta potential, and morphology. The nanovesicles were incorporated into the emugel Sepineo^® P 600 (2% w/v) to provide better longer contact time with the scalp and improve physical stability. The formulation was evaluated for in vitro drug release, ex vivo drug permeation, and drug deposition studies. Follicular deposition of the vesicles was also evaluated using a differential tape stripping technique and elucidated using confocal microscopy. The optimum oleic acid vesicles measured particle size was 317 ± 4 nm, with high entrapment efficiency (69.08 ± 3.07%), narrow PDI (0.203 ± 0.01), and a negative zeta potential of −13.97 ± 0.451. The in vitro drug release showed the sustained release of MXD from vesicular gel. The skin permeation and deposition studies revealed superiority of the prepared MXD vesicular gel (0.2%) in terms of MXD deposition in the stratum corneum (SC) and remaining skin over MXD lotion (2%), with enhancement ratios of 3.0 and 4.0, respectively. The follicular deposition of MXD was 10-fold higher for vesicular gel than the control. Confocal microscopy also confirmed the higher absorption of rhodamine via vesicular gel into hair follicles as compared to the control. Overall, the current findings demonstrate the potential of oleic acid vesicles for effective targeted skin and follicular delivery of MXD.