Dermal microneedles (MNs) have emerged as promising minimally invasive biomedical devices that can overcome many challenges facing conventional drug delivery strategies including the first pass metabolism limiting oral administration and the largely impermeable stratum corneum limiting topical administration. Offering painless delivery, rapid drug penetration, and the possibility of self-administration, MNs have the potential to revolutionize and enhance drug delivery through widespread use; thus, considering sustainability in MN design is of utmost importance for manufacturers, end users, and the environment. While polymers have become the preferred choice of materials in MN design, those of natural origin suffer poor mechanical properties, limited durability, and batch-to-batch variation. Alternatively, those of synthetic origin offer more robust solutions but are generally petroleum-based, including the well-established polymeric biomaterial polyethylene glycol (PEG). There is thus a dire need to design MNs which offer high performance while being eco-friendly and sustainable.

Herein, we report the development of a high renewable carbon content PEG-based stimuli-responsive MN platform for transdermal drug delivery. Importantly, over 50% of the MN content is made of components which can be produced as high renewable carbon materials, notably a high-degree crosslinker and a pH-responsive polymer. The MN arrays are fabricated by an energy-efficient, environmentally friendly, rapid, and solvent-free approach based on photopolymerization of a high renewable carbon index (RCI) mixture. While the high-degree crosslinker was incorporated into the MN base offering enhanced mechanical strength and increased RCI, the pH-responsive polymer was implemented as a smart coating and biocompatible drug carrier. Extensive drug release studies have demonstrated the platform’s ability to deliver two types of model protein drugs into artificial skin models in an effective, efficient, and pH-triggered manner. Overall, this work presents a promising strategy to boost the sustainability of MN-based drug delivery systems without compromising performance, thus enabling new avenues for eco-friendly next-generation biomedical tools.