Combining genetically engineered oxidase with hydrogen bonded organic framework (HOF) for highly efficient biocomposites.

Hydrogen bonded organic frameworks (HOFs) with enzymes incorporated during their bottom-up synthesis represent functional biocomposites with promising applications in catalysis and sensing. High enzyme loading while preserving high specific activity is fundamental for development, but to combine these biospecific features with a porous carrier is an unmet challenge. Here, we explored synthetic incorporation of D-amino acid oxidase (DAAO) with metal-free tetraamidine/tetracarboxylate-based BioHOF-1. Comparison of different DAAO forms in BioHOF-1 incorporation revealed that N-terminal enzyme fusion with the positively charged module Zbasic2 (Z-DAAO) promotes the loading (2.5-fold; ~500 mg g-1) and strongly boosts the activity (6.5-fold). To benchmark the HOF composite with metal-organic framework (MOF) composites, Z-DAAO was immobilized into the zeolitic imidazolate framework-8 (ZIF-8), the relatively more hydrophilic analogue metal azolate framework-7 (MAF-7). While sensitivity to the framework environment limited the activity of DAAO@MAF-7 (3.2 U mg-1) and DAAO@ZIF-8 (≤ 0.5 U mg-1), the activity of DAAO@BioHOF-1 was comparable (~45%) to that of soluble DAAO (50.1 U mg-1) and independent of the enzyme loading (100 – 500 mg g-1). The DAAO@BioHOF-1 composites showed superior activity with respect to every reported carrier for the same enzyme and excellent stability during solid catalyst recycling. Collectively, our results show that the fusion of the enzyme with a positively charged protein module enables the synthesis of highly active HOF biocomposites suggesting the use of genetic engineering for the preparation of biohybrid systems with unprecedented properties.

Synthesis and Characterization of a Novel Heteropoly Acid/Hydrogel Composite

Catalysis by Heteropoly acids (HPAs) and polyoxometalates (POMs) having a higher demand worldwide, as it can be designed to accelerate complex reactions and be more environmentally friendly. However, recycling of water-soluble solid catalysts remains a problem. The synthesis of a recyclable composite with catalytic properties is the key to better use of HPAs and POMs. Many researches have mentioned the method of synthesis by immersing a porous carrier in a supported solution. However, the catalytic stabilities of the previously studied composites after multiple uses have rarely been mentioned. In this research, a novel idea is proposed to synthesize a heteropoly acid supported composite. A complex hydrogel with catalytic properties was synthesized by mixing an anionic monomer with a heteropoly acid. The heteropoly acid particles were inserted inside the hydrogel by the interaction forces between the anions. Thus, preventing the water-soluble heteropoly acid from being lost during the catalytic reaction. The complex hydrogel is consisted of the anionic monomer 2-acrylamide-2methylpropanesulfonic acid (AMPS) as a carrier, N,N’-Methylenebisacrylamide (MBAA) as crosslinkers and the typical Keggin-type HPA: H3PW12O40. At last, a composite with (NH4)3PW12O40 particles was synthesized.

Development of Porous Polyurethane Implants Manufactured via Hot-Melt Extrusion

Implantable drug delivery systems (IDDSs) offer good patient compliance and allow the controlled delivery of drugs over prolonged times. However, their application is limited due to the scarce material selection and the limited technological possibilities to achieve extended drug release. Porous structures are an alternative strategy that can overcome these shortcomings. The present work focuses on the development of porous IDDS based on hydrophilic (HPL) and hydrophobic (HPB) polyurethanes and chemical pore formers (PFs) manufactured by hot-melt extrusion. Different PF types and concentrations were investigated to gain a sound understanding in terms of extrudate density, porosity, compressive behavior, pore morphology and liquid uptake. Based on the rheological analyses, a stable extrusion process guaranteed porosities of up to 40% using NaHCO3 as PF. The average pore diameter was between 140 and 600 µm and was indirectly proportional to the concentration of PF. The liquid uptake of HPB was determined by the open pores, while for HPL both open and closed pores influenced the uptake. In summary, through the rational selection of the polymer type, the PF type and concentration, porous carrier systems can be produced continuously via extrusion, whose properties can be adapted to the respective application site.

Effects of bioporous carriers on the performance and microbial community structure in side-stream anaerobic membrane bioreactors

The aim of this study was to investigate the effects of a volcanic rock porous carrier (VRPC) on sludge reduction, pollutant removal, and microbial community structure in an anaerobic side-stream reactor (ASSR). Three lab-scale membrane bioreactors (MBRs), including an anoxic–oxic MBR, which served as the control (C-MBR), an ASSR-coupled MBR (A-MBR), and an A-MBR filled with VRPC (FA-MBR) were stably and simultaneously operated for 120 days. The effect of the three reactors on the removal of chemical oxygen demand (COD) was almost negligible (all greater than 95%), but the average removal efficiency of ammonium nitrogen, total nitrogen, and total phosphorus was significantly improved by the insertion of an ASSR, especially when the ASSR was filled with VRPC. Finally, A-MBR and FA-MBR achieved 16.2% and 26.4% sludge reduction rates, with observed sludge yields of 0.124 and 0.109 g mixed liquid suspended solids/g COD, respectively. Illumina MiSeq sequencing revealed that microbial diversity and richness were highest in the VRPC, indicating that a large number of microorganisms formed on the carrier surface in the form of a biofilm. Abundant denitrifying bacteria (Azospira, Comamonadaceae_unclassified, and Flavobacterium) were immobilized on the carrier biofilm, which contributed to increased nitrogen removal. The addition of a VRPC to the ASSR successfully immobilized abundant hydrolytic, fermentative, and slow-growing microorganisms, which all contributed to reductions in sludge yield.

Study Insulating and Cooling Properties of the Material on the Basis of Crushed Foam Glass and Determination of its Extinguishing Characteristics with the Attitude to Alcohols

To extinguish alcohols, it is proposed to use a two-layer material consisting of a layer of a light porous carrier, on which an insulating gel layer is applied. The use of crushed foam glass as a porous carrier is justified. To obtain an insulating layer of gel, it is proposed to use a gel-forming system CaCl2 + Na2 O · 2.7 SiO2 . The insulating and cooling properties with respect to the alcohols of two separate layers and the buoyancy of a crushed foam glass layer are determined. The cooling properties of the two-layer foam glass - gel material were evaluated. To increase the cooling properties of the foam glass, it is proposed to wet it. It was found that, at the same time as the cooling effect increases, wetting of the foam glass leads to a decrease in its buoyancy and insulating properties with respect to alcohol vapors. The heights of dry and wetted foam glass layers necessary to stop the combustion of one, two, and three atomic alcohols were experimentally determined. It is concluded that alcohols can be quenched with dry and moistened foam glass, both with a gel layer applied to its surface and without a gel layer.

Synthesis of Carbon Onion and Its Application as a Porous Carrier for Amorphous Drug Delivery

Given the great potential of porous carrier-based drug delivery for stabilising the amorphous form of drugs and enhancing dissolution profiles, this work is focussed on the synthesis and application of carbon onion or onion-like carbon (OLC) as a porous carrier for oral amorphous drug delivery, using paracetamol (PA) and ibuprofen (IBU) as model drugs. Annealing of nanodiamonds at 1100 °C produced OLC with a diamond core that exhibited low cytotoxicity on Caco-2 cells. Solution adsorption followed by centrifugation was used for drug loading and results indicated that the initial concentration of drug in the loading solution needs to be kept below 11.5% PA and 20.7% IBU to achieve complete amorphous loading. Also, no chemical interactions between the drug and OLC could be detected, indicating the safety of loading into OLC without changing the chemical nature of the drug. Drug release was complete in the presence of sodium dodecyl sulphate (SDS) and was faster compared to the pure crystalline drug, indicating the potential of OLC as an amorphous drug carrier.