Silk-Based Biomimetics Made by the Molecular Imprinting Technique—Exploiting Protein Aggregation Versus Protein Structuration to Form Target-Selective Nanotraps

We report about tailor-made biomimetics stemmed from merging biology with polymer chemistry and material science. Aqueous-soluble nanotraps that behave as biomimetic receptors were prepared in the form of protein super-assemblies fixed by non-natural crosslinking. The starting material to form the nanotrap were biocompatible, nontoxic proteins, already in use in regenerative medicine, such as silk fibroin [1].<br/>Molecular recognition was conveyed to the nanotraps by the unconventional exploitation of the molecularly imprinted polymers (MIPs) technique, that is a strategy to entail molecular recognition to a nanomaterial by means of a template-assisted synthesis [2,3]. The unicity of the present approach lays in the exploitation of proteins, such as silk fibroin, as building block for the formation of the nanotraps.<br/>Silk fibroin was methacrylated (SilMA) prior to use it as a macromolecular building block. SilMA was then placed in solution with the target analyte and the physicochemical conditions were optimized by means of surface response method to yield to discrete nucleation of SilMA nanoaggregates. The nanotraps were obtained in the form of disordered aggregation of proteins, or by the nucleation of discrete beta-structured protein superstructures.<br/>The imprinted silk-nanotraps, called bioMIPs, were physically and functionally characterized, demonstrating high affinity binding (nM) for the targets and selectivity [4]. Enzymatic degradation of the bioMIPs was studied. The biocompatibility of the nanotraps was confirmed. The nanotraps were further labelled with fluorescent tags and tested for imaging in cell cultures [6].<br/>The formation of the silk bioMIPs is paradigmatic of the role that protein aggregation versus protein secondary structure formation can play in the formation of functional nanobiomaterials, standing as a novel approach for the preparation of selective nanobiomaterials. The bioMIP’s synthesis proved general to entail recognition towards biotargets [4,5], with perspective to sequester molecular players in vitro and in vivo, for the ultimate control of diseases, and for further translation in clinical uses.<br/>References<br/>1. B. Kundu, R. Rajkhowa, S.C. Kundu, X. Wang Adv. Drug Deliv. Rev. 2013, 65, 457.<br/>2. Y. Hoshino, T. Kodama, Y. Okahata, K.J. Shea J. Am. Chem. Soc. 2008, 130, 15242.<br/>3. S. Piletsky, F. Canfarotta, A. Poma, A.M. Bossi, S. Piletsky, Trends Biotechnol. 2020, 38, 368.<br/>4. A.M. Bossi, A. Bucciarelli, D. Maniglio, ACS Appl. Mater. Interfaces, 2021, 13, 312431.<br/>5. A.M. Bossi, D. Maniglio, Microchem. Acta, 2022, 189, 66.<br/>6. D. Maniglio, F. Agostinacchio, A.M. Bossi, MRS Advances, 2023.