Engineering Pyrrolysyl-tRNA Synthetase for the Incorporation of Non-Canonical Amino Acids with Smaller Side Chains

Site-specific incorporation of non-canonical amino acids (ncAAs) into proteins has emerged as a universal tool for systems bioengineering at the interface of chemistry, biology, and technology. The diversification of the repertoire of the genetic code has been achieved for amino acids with long and/or bulky side chains equipped with various bioorthogonal tags and useful spectral probes. Although ncAAs with relatively small side chains and similar properties are of great interest to biophysics, cell biology, and biomaterial science, they can rarely be incorporated into proteins. To address this gap, we report the engineering of PylRS variants capable of incorporating an entire library of aliphatic “small-tag” ncAAs. In particular, we performed mutational studies of a specific PylRS, designed to incorporate the shortest non-bulky ncAA (S-allyl-l-cysteine) possible to date and based on this knowledge incorporated aliphatic ncAA derivatives. In this way, we have not only increased the number of translationally active “small-tag” ncAAs, but also determined key residues responsible for maintaining orthogonality, while engineering the PylRS for these interesting substrates. Based on the known plasticity of PylRS toward different substrates, our approach further expands the reassignment capacities of this enzyme toward aliphatic amino acids with smaller side chains endowed with valuable functionalities.

A Greener Recyclable Process for Extraction of Microbial Melanin using Ionic Liquid

Melanins have multidimensional applications in medical and biomaterial science and thereby shooting up its demand. Conventional extraction techniques has many disadvantages like poor extraction efficiency, use of toxic solvents (acid and base), time-consuming, and consequent higher cost of the final product. To tackle this problem, an innovative ionic liquid (IL) based approach was used for the extraction and purification of melanin from the endophyte Streptomyces hyderabadensis strain 7VPT5-5R. ILs are furnished with best thermal, chemical, electrochemical stability, non flammability, trivial volatility, and broad range of solubility making them a promising medium for the extraction of melanin. Maximum yield 5.5 g/L was obtained by IL extraction method which is remarkably higher than conventional acid-precipitation method. The devised method also allows recyling of IL five times without loosing efficinecy, thus reducing use of fresh IL. Furthermore, the process is scalable, eco-friendly, rapid and produce superior quality melanin than that of the conventional method.

Peculiarities of promiscuous l-threonine transaldolases for enantioselective synthesis of β-hydroxy-α-amino acids

The introduction of β-hydroxy-α-amino acids (βHAAs) into organic molecules has received considerable attention as these molecules have often found widespread applications in bioorganic chemistry, medicinal chemistry and biomaterial science. Despite innovation of asymmetric synthesis of βHAAs, stereoselective synthesis to control the two chiral centres at Cα and Cβ positions is still challenging, with poor atomic economy and multi protection and deprotection steps. These syntheses are often operated under harsh conditions. Therefore, a biotransformation approach using biocatalysts is needed to selectively introduce these two chiral centres into structurally diverse molecules. Yet, there are few ways that enable one-step synthesis of βHAAs. One is to extend the substrate scope of the existing enzyme inventory. Threonine aldolases have been explored to produce βHAAs. However, the enzymes have poor controlled installation at Cβ position, often resulting in a mixture of diastereoisomers which are difficult to be separated. In this respect, l-threonine transaldolases (LTTAs) offer an excellent potential as the enzymes often provide controlled stereochemistry at Cα and Cβ positions. Another is to mine LTTA homologues and engineer the enzymes using directed evolution with the aim of finding engineered biocatalysts to accept broad substrates with enhanced conversion and stereoselectivity. Here, we review the development of LTTAs that incorporate various aldehyde acceptors to generate structurally diverse βHAAs and highlight areas for future developments. Key points • The general mechanism of the transaldolation reaction catalysed by LTTAs • Recent advances in LTTAs from different biosynthetic pathways • Applications of LTTAs as biocatalysts for production of βHAAs

XT-type DNA Hydrogels Loaded with VEGF and NGF Promote Peripheral Nerve Regeneration via Biphasic Release Profile

Peripheral nerve injury (PNI) remains an unresolved challenge in the medicine area. With the development of biomaterial science and tissue engineering, a variety of nerve conduits were widely applied in...

Bone-like ceramic scaffolds designed with bioinspired porosity induce a different stem cell response

Biomaterial science increasingly seeks more biomimetic scaffolds that functionally augment the native bone tissue. In this paper, a new concept of a structural scaffold design is presented where the physiological multi-scale architecture is fully incorporated in a single-scaffold solution. Hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP) bioceramic scaffolds with different bioinspired porosity, mimicking the spongy and cortical bone tissue, were studied. In vitro experiments, looking at the mesenchymal stem cells behaviour, were conducted in a perfusion bioreactor that mimics the physiological conditions in terms of interstitial fluid flow and associated induced shear stress. All the biomaterials enhanced cell adhesion and cell viability. Cortical bone scaffolds, with an aligned architecture, induced an overexpression of several late stage genes involved in the process of osteogenic differentiation compared to the spongy bone scaffolds. This study reveals the exciting prospect of bioinspired porous designed ceramic scaffolds that combines both cortical and cancellous bone in a single ceramic bone graft. It is prospected that dual core shell scaffold could significantly modulate osteogenic processes, once implanted in patients, rapidly forming mature bone tissue at the tissue interface, followed by subsequent bone maturation in the inner spongy structure.

Investigation of PLA-PEG-45S5 Bioactive Glass Composite Enhancement on Bioactivity

Bioactivity is an important aspect in biomaterial science ensuring materials used are safe for clinical application. The study describes fabrication of composites containing polylactic acid (PLA) – polyethylene glycol (PEG) with incorporation of sol-gel derived 45S5 bioactive glass (BG). Thermal analysis via Differential Thermal Analysis shows a favorable point over degree of crystallization that influence cells attachment, although non-significant difference in values indicates BG has homogenously dispersed. This correlates to X-ray diffraction analysis where non-significant difference is seen in intensities of the diffraction peaks, which confirms low impact of BG brittleness properties over the fabricated composite. Composites’ pH and degradation study in Simulated Body Fluid shows a steady increment profile over time and lower degradation rate for the composite after incorporation of BG. In vitro cell proliferation study also showed that HDF cells seeded on composite film of P/BG2.5 exhibit highest cell viability with steady increment of proliferation throughout the observation period.

Biocompatibility in regenerative nanomedicine

Biocompatibility is a very common word that is used within biomaterial science and used for description of the interactions between the foreign material and the body. However, the meaning of biocompatibility as well as the mechanisms that collectively constitutes is still unclear. With the advance of nanotechnology, new concerns have been observed related to biocompatibility of these biomaterials. Due to their small size and variability of their physical and chemical properties, nanoparticles’ (NP) distribution within the body and interactions with the target cells and tissues are highly variable. Here, we tried to provide an overview about NPs, the concept of biocompatibility and biocompatibility-related issues in nanomedicine and several different NPs.

Therapeutic Applications of Nanobiomaterials

The most exciting advancement in the fields of biomaterial science is its ability to engineer new materials at the nanoscale level for various biological applications particularly drug and gene delivery for therapeutic applications. The main focus of this chapter is to review the therapeutic applications of different nanobiomaterials. Thus, it is proposed to discuss type of nanobiomaterials, general biological barriers for therapeutics, surface functionalization of nanobiomaterials and their therapeutics application in the present chapter. The therapeutic applications are explained on the basis of type of nanobiomaterials. The biocompatibility and toxicological response towards nanobiomaterials is an important issue that requires investigation for clinical development and their commercialization. The commercial prospects and future challenges in development of nanobiomaterials particularly for drug delivery are also discussed in the present chapter.