No abstract

Owing to the large contact surface area in geometry, disc-shaped polymer particles and their fascinating properties compared to those of spherical particles have received increasing attention. Although a variety of methods have been developed, fabricating polymer discs in a facile and versatile manner remains a challenge. In this study, we propose a method to fabricate polymer discs by a hot-press process combined with a sacrificial matrix technique, where only aqueous solutions and suspensions are employed. By embedding polymer microspheres in alginate gel, space between the microspheres is created, and thus, the microspheres can be deformed into individual discs after hotpressing near the T g of the polymer. As case studies, polystyrene, poly(L-lactic acid), and poly(D,L-lactide-co-glycolide) microspheres with a wide range of sizes were processed into polymer discs. The choice of sacrificial matrix and the optimal condition for hot-pressing are also discussed. Moreover, the high interfacial adhesion of the prepared discs was verified, including the adhesiveness of polymer discs to the surface of a cover glass under airflow, as well as the enhancement of aggregation for bovine serum albumin-coated polymer discs in the presence of glutaraldehyde. We suggest that the enhanced adhesiveness of polymer discs can improve their performances in both particle-based targeted drug delivery and latex turbidimetric immunoassay.

The key factor of polymer particles using as a drug carrier is the ability to adhere to the surface of the target sites in order to optimize the drug delivery efficiency. To this end, shape of the particles is one of the essential parameters since nonspherical particles such as discs theoretically have more contact surface area than spherical particles. We herein propose a facile method to fabricate elongated polymer micro/nano discs by combining phase separation and a roll-to-roll coating process with a stretching method. By roll-to-roll coating, biodegradable poly(lactide-co-glycolide) (PLGA) discs formed on polyvinyl alcohol (PVA) film can be instantly stretched by uniaxial stretcher. The effect of stretching temperature and percentage of film elongation on the particle morphology was studied. The results showed that the PLGA discs can be elongated and the aspect ratio of 2.3 can be achieved with 600% elongation at 80 C, reflecting the increase of estimated contact surface area by 1.8 times. The adhesion efficiency of these elongated discs was compared with discs before stretching, spheres, and elongated spheres by using the water-dropping test. The elongated discs showed the best result among these particles and their adhesion efficiency are strongly related to estimated contact surface area.