Polymer homologue-mediated formation of hydrogel microneedles for controllable transdermal drug delivery

Poly(ethylene glycol) diacrylate (PEGDA) microneedles (MNs) are hydrogel-based devices that achieve controlled drug delivery kinetics by adjusting the crosslinking density. However, the biosafety of many crosslinking agents used to regulate crosslinking density is not ideal. To avoid crosslinking agents and simplify the preparation process, using two types of polymer homologues with different number-average molecular weights, we have successfully developed a series of PEGDA MNs with controllable crosslinking density (abbreviated as TP-X MNs). The research showed that the mechanical properties and drug release behavior of TP-X MNs could be tuned by simply controlling the weight proportion of two different PEGDA components in MNs. Ex vivo drug delivery experiments indicated that all TP-X MNs exhibited a sustained release profile, and their control range of 336-hour accumulative release rates was from 6.24% to 40.93%. Moreover, we prepared a novel dual-layer PEDGA MN, which can customize the drug loading and release rate in each layer of MN. This work demonstrates a new way to develop hydrogel MNs with adjustable crosslink density and broadens the applications of PEGDA MN in the biomedical field.