Construction of the lactate-sensing fibremats by confining sensor fluorescent protein of lactate inside nanofibers of the poly(HPMA/DAMA)/ADH-nylon 6 core–shell fibremat

The development of a new materials platform capable of sustaining the functionality of proteinous sensor molecules over an extended period without being affected by biological contaminants in living systems, such as proteases, is highly demanded. In this study, our primary focus was on fabricating new core–shell fibremats using unique polymer materials, capable of functionalizing encapsulated sensor proteins while resisting the effects of proteases. The core-fibre parts of core–shell fibremats were made using a newly developed post-crosslinkable water-soluble copolymer, poly(2-hydroxypropyl methacrylamide)-co-poly(diacetone methacrylamide), and the bifunctional crosslinking agent, adipic dihydrazide, while the shell layer of the nanofibers was made of nylon 6. Upon encapsulating the lactate-sensor protein eLACCO1.1 at the core-fibre part, the fibremat exhibited a distinct concentration-dependent fluorescence response, with a dynamic range of fluorescence alteration exceeding 1000% over the lactate concentration range of 0 to 100 mM. The estimated dissociation constant from the titration data was comparable to that estimated in a buffer solution. The response remained stable even after 5 cycles and in the presence of proteases. These results indicates that our core–shell fibremat platform could serve as effective immobilizing substrates for various sensor proteins, facilitating continuous and quantitative monitoring of various low-molecular-weight metabolites and catabolites in a variety of biological samples.