Molecularly Imprinted Silk Fibroin Nanoparticles

Abstract

Nanosized biomimetics prepared by the strategy of molecular imprinting, that is, the stamping of recognition sites by means of a template-assisted synthesis, are demonstrating potential as plastic antibodies in medicine, proving effective for cell imaging and targeted therapies. Most molecularly imprinted nanoparticles (MIP-NPs) are currently made of soft matter, such as polyacrylamide and derivatives. Yet, MIP-NPs biocompatibility is crucial for their effective translation into clinical uses. Here, we propose the original idea to synthesize fully biocompatible molecularly imprinted nanoparticles starting from the natural polymer silk fibroin (MIP SF-NPs), which is nontoxic and highly biocompatible. The conditions to produce MIP SF-NPs of different sizes ( d mean ∼ 50 nm; d mean ∼ 100 nm) were set using the response surface method. The stamping of a single, high affinity ( K D = 57 × 10 –9 M), and selective recognition site per silk fibroin nanoparticle was demonstrated, together with the confirmation of nontoxicity. Additionally, MIP SF-NPs were used to decorate silk microfibers and silk nanofibers, providing a general means to add entailed biofunctionalities to materials.

BioMIPs: molecularly imprinted silk fibroin nanoparticles to recognize the iron regulating hormone hepcidin

“…The preparation of the imprinted, silk fibroin–based nanoparticles, called bioMIPs, was adapted from the protocol published earlier [ 21 ]. Briefly, the starting material, methacrylated SF or SilMA [ 23 ], was diluted in aqueous conditions (PBS, final V = 4 mL) to the concentration of 0.03% w/v [ 21 ].…”

“…The preparation of the imprinted, silk fibroin–based nanoparticles, called bioMIPs, was adapted from the protocol published earlier [ 21 ]. Briefly, the starting material, methacrylated SF or SilMA [ 23 ], was diluted in aqueous conditions (PBS, final V = 4 mL) to the concentration of 0.03% w/v [ 21 ]. It is expected that, due to these highly diluted conditions, the SF proteins that spontaneously form supramolecular aggregates are forced to aggregate in a limited number of units, ultimately yielding to the formation of SF-nanoparticles (SF-NPs).…”

“…Recently, we reported the preparation of silk fibroin imprinted nanoparticles (MIP SF-NPs) [ 21 ] starting from the natural biocompatible material silk fibroin (SF) [ 22 ]. SF is a protein characterized by a heavy (~390 kDa) and a light chain (~26 kDa) linked together via a single disulfide bond.…”

“…SilMA possesses pendant double bonds, ideal to be crosslinked during the imprinting process as these can be exploited to stabilize the formed MIP nanoparticle. As a template, to proof the feasibility of imprinting SF-nanoparticles, initially we choose the protein albumin (~66 kDa) [ 21 ]. Results indicated that the amount of SilMA in the synthesis solution directly correlated to the size of the formed MIP SF-nanoparticles (50 or 100 nm).…”

“…The MIP SF-nanoparticles demonstrated selective and specific binding for their targeted protein. Cell viability assays on mouse embryotic fibroblasts showed that the SF MIP nanoparticles were cyto-compatible even at high concentrations (1.5 mg/mL) [ 21 ]; thus, the MIP SF-nanoparticles can fully be considered tailor-made functional biological biomimetics, deserving the specific name “bioMIPs.”…”