We report the photo-induced degradation of and cargo release from a nanoscale metal-organic framework (nMOF) incorporating photo-isomerizable 4,4'-azobenzenedicarboxylate (AZB) linkers. The structure matches a UiO-type framework where 12 4,4'-azobenzenedicarboxylate moieties are connected to a ZrO(OH) cluster, referred to as UiO-AZB. Due to the incorporation of photo-isomerizable struts, the degradation of UiO-AZB is accelerated by irradiation with white light (1.3 ± 0.1% h under dark conditions vs. 8.4 ± 0.4% h when irradiated). Additionally, we show slow release of Nile Red (NR) which is triggered by irradiation (0.04 ± 0.01% h under dark conditions vs. 0.36 ± 0.02% h when irradiated).
In the past two decades, keratin biomaterials have shown impressive results as scaffolds for tissue engineering, wound healing, and nerve regeneration. In addition to its intrinsic biocompatibility, keratin interacts with specific cell receptors eliciting beneficial biochemical cues. However, during extraction from natural sources, such as hair and wool fibers, natural keratins are subject to extensive processing conditions that lead to formation of unwanted by-products. Additionally, natural keratins suffer from limited sequence tunability. Recombinant keratin proteins can overcome these drawbacks while maintaining the desired chemical and physical characteristics of natural keratins. Herein, we present the bacterial expression, purification, and solution characterization of human hair keratins K31 and K81. The obligate heterodimerization of the K31/K81 pair that results in formation of intermediate filaments is maintained in the recombinant proteins. Surprisingly, we have for the first time observed new zero- and one-dimensional nanostructures from homooligomerization of K81 and K31, respectively. Further analysis of the self-assembly mechanism highlights the importance of disulfide crosslinking in keratin self-assembly.
Proteins and peptides have attracted much attention as templates for one-pot synthesis of biocompatible gold nanoparticles. While numerous natural and de novo protein sequences have been used, the actual mechanism of nanoparticle nucleation and growth from the protein matrix is not well understood. In this study we utilized engineered consensus tetratricopeptide repeat protein (CTPR) to probe the bioinorganic interface during gold nanoparticle synthesis. The binding of CTPR to gold ions and the gold nanoparticle surface was investigated using fluorescence spectroscopy and heteronuclear single quantum coherence NMR spectroscopy to provide residue-specific measurements. This work provides a foundation for the rational design of proteins for synthesis of tailored functional nanomaterials for biological, medical, and optical applications.
Gold nanotriangles (Au NTs) with tunable edge length were synthesized via a green chemical route in the presence of the designed consensus sequence tetratricopeptide repeat (CTPR) protein, halide anions (Br(-)) and CTPR-stabilized Ag seeds. The well-defined morphologies, tailored plasmonic absorbance from visible-light to the near infrared (NIR) region, colloidal stability and biocompatibility are attributed to the synergistic action of CTPR, halide ions, and CTPR-stabilized Ag seeds.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.