Polyethylene Glycol Nanofiller for Robust Lyophilization of Graphically Encoded Hydrogel Microparticles

Graphically encoded hydrogel microparticle-based biosensing is a promising suspension microarray platform by virtue of multiplexing capability, robust sensitivity, and facilitated downstream analysis. However, the absence of a long-term and stable storage protocol for the hydrogel microparticle has been a bottleneck for the sensing platform to be adapted to practical fields. In this study, the polyethylene glycol (PEG) nanofiller-mediated lyophilization strategy of the hydrogel microparticles is presented. To inhibit the lyophilization-induced deformation of the porous structure and geometries of the particles, PEG is utilized as the filler material occupying the porous region in the hydrogel particles to prevent the interaction between polymer chains and the collapse of the porous structure. Based on the filler effect, the high decoding accuracy (more than 95%) for the lyophilized microparticles after reconstitution can be achieved by outstanding preservation of the particle geometries. Furthermore, the immunoassay performance of the antibody-functionalized microparticles lyophilized with PEG nanofiller is comparable to that of the non-lyophilized particles. Finally, the possibility of long-term storage (more than 6 months) of the lyophilized microparticles is confirmed by thermal aging. This finding is expected to promote the hydrogel microparticle-based sensing platform to be extended to practical fields via the innovation of the storage protocol.