Development and molecular modeling studies of new thiadiazole piperazine urea derivatives as potential fatty acid amide hydrolase inhibitors.

A series of novel piperazine urea derivatives with thiadiazole moieties were designed, synthesized, and investigated for their inhibition potential against human fatty acid amide hydrolase (hFAAH). The urea derivatives possessing p-chlorophenylthiadiazole and benzylpiperazine fragments (19-22) were effective inhibitors of hFAAH. Notably, compounds with 4-chlorobenzyl (19) and 4-fluorobenzyl (20) tails at the piperazine side were identified as the most active inhibitors with IC50 values of 0.13 and 0.22 µM, respectively. The preincubation test of 19 was in agreement with the irreversible binding mechanism. Molecular docking was performed to explore the potential binding interactions with key amino acid residues at the FAAH active site. These newly identified inhibitors could serve as leads for the further development of potent and selective FAAH inhibitors for FAAH-associated diseases.

Fabrication of Amyloid Curli Fibers-Alginate Nanocomposite Hydrogels with Enhanced Stiffness.

Alginate hydrogels are biocompatible, biodegradable, low-cost, and widely used as bioinks, cell encapsulates, three-dimensional culture matrices, drug delivery systems, and scaffolds for tissue engineering. Nevertheless, their limited stiffness hinders their use for certain biomedical applications. Many research groups have tried to address this problem by reinforcing alginate hydrogels with graphene, carbon nanotubes, or silver nanoparticles. However, these materials present nanotoxicity issues, limiting their use for biomedical applications. Other studies show that electrospinning or wet spinning can be used to fabricate biocompatible, micro- and nanofibers to reinforce hydrogels. As a relatively simple and cheap alternative, in this study we used bioengineered bacteria to fabricate amyloid curli fibers to enhance the stiffness of alginate hydrogels. We have fabricated for the first time bioengineered amyloid curli fibers-hydrogel composites and characterized them by a combination of (i) atomic force microscopy (AFM) to measure the Young's modulus of the bioengineered amyloid curli fibers and study their topography, (ii) nanoindentation to measure the Young's modulus of the amyloid curli fibers-alginate nanocomposite hydrogels, and (iii) Fourier-transform infrared spectroscopy (FTIR) to analyze their composition. The fabricated nanocomposites resulted in a highly improved Young's modulus (up to 4-fold) and showed very similar physical and chemical properties, opening the window for their use in applications where the properties alginate hydrogels are convenient but do not match the stiffness needed.

Addressable self-immobilization of lactate dehydrogenase across multiple length scales.

Successful nanobiotechnology implementation largely depends on control over the interfaces between inorganic materials and biological molecules. Controlling the orientations of biomolecules and their spatial arrangements on the surface may transform many technologies including sensors, to energy. Here, we demonstrate the self-organization of L-lactate dehydrogenase (LDH), which exhibits enhanced enzymatic activity and stability on a variety of gold surfaces ranging from nanoparticles to electrodes, by incorporating a gold-binding peptide tag (AuBP2) as the fusion partner for Bacillus stearothermophilus LDH (bsLDH). Binding kinetics and enzymatic assays verified orientation control of the enzyme on the gold surface through the genetically incorporated peptide tag. Finally, redox catalysis efficiency of the immobilized enzyme was detected using cyclic voltammetry analysis in enzyme-based biosensors for lactate detection as well as in biofuel cell energy systems as the anodic counterpart. Our results demonstrate that the LDH enzyme can be self-immobilized onto different gold substrates using the short peptide tag under a biologically friendly environment. Depending on the desired inorganic surface, the proposed peptide-mediated path could be extended to any surface to achieve single-step oriented enzyme immobilization for a wide range of applications.