Microneedles (MNs) have been extensively developed over the last two decades, and highly efficient drug delivery was demonstrated with their minimal invasiveness via a transdermal route. Recently, MNs have not only been applied to the skin but also to other tissues such as blood vessels, scleral tissue, and corneal tissue. In addition, the objective of the MN application has been diversified, ranging from drug delivery to wound closure and biosensing. However, since most MN fabrication methods are expensive and time-consuming, they are inappropriate to prototype MNs for various tissues that have different and complex anatomies. Although several drawing-based techniques have been introduced for rapid MN production, they fabricated MNs with limited shapes, such as thin MNs with wide bases. In this study, we propose a three-step thermal drawing for rapid, prototyping MNs that can have a variety of shapes and can be fabricated on curved surfaces. Based on the temperature control of polymer bridge formation during thermal drawing, the body profile and aspect ratios of MNs were conveniently controlled, and the effect of temperature control on the body profile of MNs was explained. Thermally drawn MNs with different shapes were fabricated both on flat and curved surfaces, and they were characterized in terms of their mechanical properties and insertion into vascular tissue to find an optimal shape for vascular tissue insertion.

The physiological and toxicological evaluation of nano-silicon dioxide (nano-SiO₂) particles in food is important for ensuring food safety. In this study, nano-SiO₂ particles isolated from five brands of instant coffee, were structurally characterized using transmission electron microscopy, X-ray diffraction, Fourier-transform infrared spectroscopy, dynamic light scattering, and zeta potential analyses. Their toxicity was assessed by measuring cell viability, membrane integrity, and reactive oxygen species (ROS) levels in model gastrointestinal cells (GES-1 and Caco-2). Additionally, mortality, deformity rate, heart rate and death of whole zebra fish embryos were measured. The five types of nano-SiO₂ samples comprised amorphous particles with a purity of approximately 99%, which met the food additive standard. Considering that the original particle size ranged from 10 to 50 nm, the samples were classified as nano-SiO₂ food additives. Nano-SiO₂ did not significantly impact the activity of GES-1 or Caco-2 cells, and no significant cell membrane damage was observed (Caco-2 cells exhibited mild micro damage); however, a slight increase in intracellular RPS levels was detected. Moreover, nano-SiO₂ was found to cause head deformity, pericardial edema, yolk sac edema and tail bending. Collectively, the results show that nano-SiO₂ time- and dose-dependently affects GES-1 and Caco-2 cell viability, as well as the mortality, heart rate, and abnormality rate of zebra fish embryos. Specifically, a high concentration (≥ 200 μg/mL) and long exposure time (≥ 48 h) of food additive nano-SiO₂ affected GES-1, Caco-2 cells, and the gastrointestinal tract in zebra fish embryos.

Restenosis at a vascular anastomosis site is a major cause of graft failure and is difficult to prevent by conventional treatment. Perivascular drug delivery has advantages as drugs can be diffused to tunica media and subintima while minimizing the direct effect on endothelium. This in vivo study investigated the comparative effectiveness of paclitaxel, sirolimus, and sunitinib using a perivascular biodegradable microneedle cuff. A total of 31 New Zealand white rabbits were used. Rhodamine was used to visualize drug distribution (n = 3). Sirolimus- (n = 7), sunitinib- (n = 7), and paclitaxel-loaded (n = 7) microneedle cuffs were placed at balloon-injured abdominal aortae and compared to drug-free cuffs (n = 7). Basic histological structures were not affected by microneedle devices, and vascular wall thickness of the device-only group was similar to that of normal artery. Quantitative analysis revealed significantly decreased neointima formation in all drug-treated groups (p < 0.001). However, the tunica media layer of the paclitaxel-treated group was significantly thinner than that of other groups and also showed the highest apoptotic ratio (p < 0.001). Proliferating cell nuclear antigen (PCNA)-positive cells were significantly reduced in all drug-treated groups. Sirolimus or sunitinib appeared to be more appropriate for microneedle devices capable of slow drug release because vascular wall thickness was minimally affected.

Cardiovascular diseases remain the leading cause of death worldwide, largely due to sudden blockage or narrowing of coronary arteries, with myocardial infarction and angina as common outcomes. Stent implantation is a widely used intervention to restore vessel patency, offering advantages such as reduced invasiveness, faster recovery, and improved patient comfort compared to surgery. However, complications including in‐stent restenosis, elastic recoil, and stent migration persist. Among these, stent dislodgement poses a particularly severe risk, underscoring the need for improved anchoring strategies. Microneedles (MNs), recognized for their minimal invasiveness and strong tissue‐fixation capability, present an attractive but unexplored approach for vascular stents. Here, we report a novel microneedle stent (MNS) in which MN arrays were conformally integrated onto the surface of a 3D‐printed polycaprolactone stent using a UV‐curable resin transfer‐molding process. The MNs exhibited high structural fidelity, tunable mechanical strength, and stable adhesion to the stent surface, governed by UV‐crosslinking conditions. In vitro flow studies using a vessel phantom and peristaltic pump demonstrated robust anchoring under physiological conditions. Furthermore, in vivo implantation confirmed enhanced vascular fixation without adverse inflammatory responses. This work represents the first integration of MNs into vascular stents, offering a promising strategy to improve stent stability and clinical outcomes.