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Immobilized multienzyme systems are gaining momentum in applied biocatalysis; however, the coimmobilization of several enzymes on one carrier is still challenging. In this work, we exploited a heterofunctional support activated with three different chemical functionalities to immobilize a wide variety of different enzymes. This support is based on agarose microbeads activated with aldehyde, amino, and cobalt chelate moieties that allow a fast and irreversible immobilization of enzymes, enhancing the thermostability of most of the heterogeneous biocatalysts (up to 21-fold higher than the soluble one). Furthermore, this trifunctional support serves to efficiently coimmobilize a multienzyme system composed of an alcohol dehydrogenase, a reduced nicotinamide adenine dinucleotide (NADH) oxidase, and a catalase. The confined multienzymatic system demonstrates higher performance than its free counterpart, achieving a total turnover number (TTN) of 1 × 105 during five batch consecutive cycles. We envision this solid material as a platform for coimmobilizing multienzyme systems with enhanced properties to catalyze stepwise biotransformations.

Supporting schemes including the preparation of AG-Co2+/A/G, AG-Co2+/A/E, and AG-Co2+/H; supporting figures including the distribution of agarose-activated microbeads with different functionalities, immobilization and thermal inactivation kinetics, enzyme desorption assays, confocal fluorescence microscopy images of AG-Co2+/A/G, spectra of intrinsic protein fluorescence, residual activity of HBs under operation conditions and consumed 1,5-pentanediol after 24 h by the soluble or coimmobilized enzymes; supporting tables including the activation degree of agarose microbeads, heterofunctional activation of agarose microbeads, abbreviation of the differently prepared supports, single-enzyme immobilization parameters on AG-Co2+/E microbeads, and thermal stability of soluble enzymes and individual residual activity of coimmobilized enzymes after five batch cycles.

Production of enantiomerically pure molecules is of utmost importance in the pharma industry. In this context, biocatalysis emerges as an alternative to conventional chemical methods due to the exquisite selectivity and specificity underlying the enzymes. In this work, we design a multienzymatic system to perform the deracemization of alkyl glyceryl ethers as potential building blocks for the synthesis of drugs. The key to success in this route is controlling the spatial organization of the enzymes involved in the cascade through their immobilization on porous carriers. By fine tuning the intraparticle organization of an enzymatic cascade comprising an (S)-selective glycerol dehydrogenase from Bacillus stearothermophilus and an (R)-selective ketoreductase from Lactobacillus kefir, we performed the oxidoreductive deracemization of rac-alkyl/aryl glyceryl ethers with a yield up to 100% and enantiomeric excess e.e. > 99%, otherwise impossible using a soluble system. Remarkably, we find that optimal spatial assembly of the biocatalyst ameliorates the inhibition phenomena experimented by the system and increases the deracemization rate by 4-fold. Finally, integrating an enzymatic nicotinamide adenine dinucleotide oxidized disodium salt (NAD+) regeneration system to the heterogeneous biocatalyst, we intensified the process by reusing it in discontinuous and consecutive batch cycles and scaling the reaction up to 250 mM substrate, achieving 100% yield and e.e. > 99%.

Self-sufficient heterogeneous biocatalysts (ssHB) are promising candidates for implementing cofactor-dependent enzymes in chemical biomanufacturing. Most strategies for coimmobilizing cofactors with dehydrogenases on porous agarose microbeads involve the use of cationic polymers (i.e., polyethylenimine, PEI) that interact electrostatically with the phosphate groups of their corresponding phosphorylated cofactors. Although the latter is a powerful and versatile approach, ionic bonds are disrupted in biotransformations operating at a high ionic strength, where screening of bonded ions takes place. Harnessing the ribose groups present in adenylated cofactors, we immobilize a selection of these (NAD(P)H, NAD(P)+, FAD, and ATP) on agarose microbeads functionalized with boronic acid to establish reversible covalent bonds between the cis-diol of the ribose in the cofactor backbone and the boronic acid. To do so, we functionalize cobalt-activated porous agarose beads with boronic acid (AG-B/Co2+) for the coimmobilization of adenylated cofactors with the corresponding cofactor dependent His-tagged dehydrogenases. First, we demonstrate that the adenylated cofactor-support interactions are reversible but show resistance against high salt concentrations, overcoming the main limitation of the current self-sufficient heterogeneous biocatalysts. Then, we coimmobilized several His-tagged enzymes with their corresponding adenylated cofactors and investigated the functionality and stability of these ssHBs in reductive aminations performed under high ionic strength in both batch and flow reactors. As a result, we manage to reuse the immobilized enzymes and the cofactors 3.5 × 105 and 167 times, respectively. This work expands the usefulness of ssBHs for hitherto bioprocess regardless of the ionic strength of the media.

Biocatalytic cascades afford the development of economically sustainable and green processes. Herein we examined the unprecedented coupling of co-immobilised Gluconobacter oxydans and an isolated transaminase to synthesise serinol from glycerol. Through this approach, we manufactured up to 36 mM serinol, the highest titer ever reported for a non-fermentative biosynthesis. More importantly, similar productivities are obtained starting from the industrial by-product crude glycerol, demonstrating the possibilities of this hybrid heterogenenous biocatalyst for valorising bio-based raw materials.

Sustainable electricity generation is one of the major current challenges for our society. In this context, the evolution of nanomaterials and nanotechnologies has enabled the fabrication of microscopic devices to produce clean energy from a great variety of renewable sources. To expand the possibilities of energy generation, we have designed and fabricated bioinorganic generators capable to produce electricity by conversion of chemical energy from renewable fuel sources. Unlike traditional generators, the systems described herein produce mechanical energy through enzyme-driven gas production which generates vibration and pressure that are thus converted into electricity by the action of a piezoelectric component properly integrated into the device. Our generators are able to produce an electric ernergy from different renewable sources like glucose, ethanol, and amino acids, attaining energy outputs around 250 nJ cm–2 and reaching maximum open-circuit voltages of up to 1 V. In addition, the produced energy can be easily regulated by adjusting both enzyme and fuel concentration which can tune the electrical output according to the application. The systems described herein propose a new concept for self-sufficient energy harvesting that bridges biocatalysis and piezoelectricity, where the energy production is based on the piezoelectric effect triggered by enzymatic action rather than on the enzyme-driven electron transfer that governs biofuel cells. Although the electric output is too low yet to be considered an alternative for energy production, this technology opens the door to power small devices. We envision the utilization of this technology in such remote locations where mechanical energy is lacking but there are chemical energy reservoirs.

Carrier-free immobilization of Candida rugosa lipase (CRL) and polymers containing primary amino groups were cross-linked using carbodiimide. To accomplish this, the free carboxyl groups of the enzyme were activated with carbodiimide-succinimide in organic medium, and then the activated proteins were cross-linked with different polyethylenimines (PEIs). The effect of the cross-linker chain length, the amount of added bovine serum albumin (BSA), and carbodiimide concentration on the catalytic properties of resulting cross-linked enzyme aggregates (CLEAs) was investigated. The CLEAs’ size, shape, specific activity, activity recovery, thermostability and enantioselectivity significantly varied according to the preparation procedure. The highest thermostable CRL-CLEA preparation was obtained with 1.3 kDa polyethyleneimine as cross-linker, 10 mg of BSA and 28 mM of carbodiimide. This preparation is 1.3-fold more active and thermostable than CLEAs prepared by the traditional method of amino cross-linking with glutaraldehyde, and retains 60% of residual activity after 22 h at 50 °C. Additionally, the CRL-CLEA preparation showed an enantioselectivity of 91% enantiomeric excess (ee). This immobilization procedure provides an alternative strategy for CLEA production, particularly for enzymes where the traditional method of cross-linking via lysine residues leads to enzyme inactivation.