A sustainable one-pot method to transform seashell waste calcium carbonate to osteoinductive hydroxyapatite micro-nanoparticles

We have developed a straightforward, one-pot, low-temperature hydrothermal method to transform oyster shell waste particles (bCCP) from the species Crassostrea gigas (Mg-calcite, 5 wt% Mg) into hydroxyapatite (HA) micro/nanoparticles. The influence of the P reagents (H3PO4, KH2PO4, and K2HPO4), P/bCCP molar ratios (0.24, 0.6, and 0.96), digestion temperatures (25-200 & DEG;C), and digestion times (1 week-2 months) on the transformation process was thoroughly investigated. At 1 week, the minimum temperature to yield the full transformation significantly reduced from 160 & DEG;C to 120 & DEG;C when using K2HPO4 instead of KH2PO4 at a P/bCCP ratio of 0.6, and even to 80 & DEG;C at a P/bCCP ratio of 0.96. The transformation took place via a dissolution-reprecipitation mechanism driven by the favorable balance between HA precipitation and bCCP dissolution, due to the lower solubility product of HA than that of calcite at any of the tested temperatures. Both the bCCP and the derived HA particles were cytocompatible for MG-63 human osteosarcoma cells and m17.ASC murine mesenchymal stem cells, and additionally, they promoted the osteogenic differentiation of m17.ASC, especially the HA particles. Because of their physicochemical features and biological compatibility, both particles could be useful osteoinductive platforms for translational applications in bone tissue engineering

Bioinspired Calcium Phosphate Coated Mica Sheets by Vapor Diffusion and Its Effects on Lysozyme Assembly and Crystallization

We propose for the first time the vapor diffusion method to deposit bioinspired calcium phosphate films on mineral substrates, that is, delaminated mica muscovite sheets and to assess the capability of these films to affect the nucleation and growth of lysozyme crystals. Deposited calcium phosphate layers were composed of octacalcium phosphate (OCP) and apatite (Ap) nanocrystals, with increased amount of OCP at higher crystallization times. In the presence of poly­(acrylic acid) (PAA) deposited layers were composed of amorphous calcium phosphate (ACP). Results of lysozyme crystallization showed that OCP/Ap-coated mica sheets slowed down the nucleation process without altering significantly the number of nucleated crystals per droplet respect to the uncoated control. ACP-coated mica sheets acted as an inhibitor, thus delaying the nucleation and reducing in addition the number of crystals. These results contrasted with the nucleation induction effect observed when calcium phosphate nanopowders were added to the crystallization drops. All coated-substrates promoted the formation of flat lysozyme crystals at the substrate–solution interface, and some of them retained its laminar morphology. Unexpectedly, the ACP coatings templated the 2D assembly of lysozyme producing thin films. The observation of the lysozyme thin films was possible only in those ACP-coated supports prepared in the presence of 0.015 and 0.02 wt % PAA

Continuous Sensing Photonic Lab-on-a-Chip Platform Based on Cross-Linked Enzyme Crystals

Microfluidics or lab-on-a-chip technology offer clear advantages over conventional systems such as a dramatic reduction of reagent consumption or a shorter analysis time, which are translated into cost-effective systems. In this work, we present a photonic enzymatic lab-on-a-chip reactor based on cross-linked enzyme crystals (CLECs), able to work in continuous flow, as a highly sensitive, robust, reusable, and stable platform for continuous sensing with superior performance as compared to the state of the art. The microreactor is designed to facilitate the in situ crystallization and crystal cross-linking generating enzymatically active material that can be stored for months/years. Thus, and by means of monolithically integrated micro-optics elements, continuous enzymatic reactions can be spectrophotometrically monitored. Lipase, an enzyme with industrial significance for catalyzed transesterification, hydrolysis, and esterification reactions, is used to demonstrate the potential of the microplatforms as both a continuous biosensor and a microreactor for the synthesis of high value compounds

Carborane Bis-pyridylalcohols as Linkers for Coordination Polymers: Synthesis, Crystal Structures, and Guest-Framework Dependent Mechanical Properties

We report the synthesis and characterization of six novel coordination polymers (CPs) based on M­(II) (M: Zn and Co), di-, tri-, and tetracarboxylate linkers and two novel bis-pyridylalcohol 1,7-bis­{(pyridin-<i>n</i>′-yl)­methanol}-1,7-dicarba-<i>closo</i>-dodecaboranes (<i>n</i>′ = 3, <b>L1</b>; <i>n</i>′ = 4, <b>L2</b>) ligands. The polycarboxylates are terephthalic acid (H₂BDC), 1,3,5-benzenetricarboxylic acid (H₃BTB), and 1,2,4,5-tetrakis­(4-carboxyphenyl)­benzene (H₄TCPB). Structural description of CPs reveals the flexibility of the carborane ligands and their ability to construct extended structures. The CP containing Co­(II), BTB, and <b>L2</b> behaves as a crystalline sponge for a variety of guests, showing a higher affinity for aromatic guest molecules. Single-crystal nanoindentation experiments indicate that a high number of specific interactions between the guests and the CP framework result in a high elastic modulus and hardness values