Recent advances in nanotechnology have provided various nanoscale materials that can be used as support for enzyme immobilization. Nanobiocatalysis integrating the biocatalyst and nanoscale materials is drawing great attention as innovative technology. Nanobiocatalysis could achieve not only a much higher enzyme loading capacity and a significantly enhanced mass transfer efficiency, but also unbelievable stabilization. In this review, we will present and discuss the recent progress in nanobiocatalysis and its applications in the fields of bioelectronics, bioconversion, and proteomics.

L-DOPA (3,4-dihydroxyphenyl-L-alanine) has been widely used as a drug for Parkinson's disease caused by deficiency of the neurotransmitter dopamine. Since Monsanto developed the commercial process for L-DOPA synthesis for the first time, most of currently supplied L-DOPA has been produced by the asymmetric method, especially asymmetric hydrogenation. However, the asymmetric synthesis shows critical limitations such as a poor conversion rate and a low enantioselectivity. Accordingly, alternative biotechnological approaches have been researched for overcoming the shortcomings: microbial fermentation using microorganisms with tyrosinase, tyrosine phenol-lyase, or p-hydroxyphenylacetate 3-hydroxylase activity and enzymatic conversion by immobilized tyrosinase. Actually, Ajinomoto Co. Ltd commercialized Erwinia herbicola fermentation to produce L-DOPA from catechol. In addition, the electroenzymatic conversion system was recently introduced as a newly emerging scheme. In this review, we aim to not only overview the biotechnological L-DOPA production methods, but also to briefly compare and analyze their advantages and drawbacks. Furthermore, we suggest the future potential of biotechnological L-DOPA production as an industrial process.

In the biorefinery using lignocellulosic biomass as feedstock, pretreatment to breakdown or loosen lignin is important step and various approaches have been conducted. For biological pretreatment, we screened Bacillus subtilis KCTC2023 as a potential lignin-degrading bacterium based on veratryl alcohol (VA) oxidation test and the putative heme-containing dye-decolorizing peroxidase was found in the genome of B. subtilis KCTC2023. The peroxidase from B. subtilis KCTC2023 (BsDyP) was capable of oxidizing various substrates and atypically exhibits substrate-dependent optimum temperature: 30°C for dyes (Reactive Blue19 and Reactive Black5) and 50°C for high redox potential substrates (2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid [ABTS], VA, and veratryl glycerol-β-guaiacyl ether [VGE]) over +1.0 V vs. normal hydrogen electrode. At 50°C, optimum temperature for high redox potential substrates, BsDyP not only showed the highest VA oxidation activity (0.13 Umg−1) among the previously reported bacterial peroxidases but also successfully achieved VGE decomposition by cleaving Cα-Cβ bond in the absence of any oxidative mediator with a specific activity of 0.086 Umg−1 and a conversion rate of 53.5%. Based on our results, BsDyP was identified as the first bacterial peroxidase capable of oxidizing high redox potential lignin-related model compounds, especially VGE, revealing a previously unknown versatility of lignin degrading biocatalyst in nature.

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Fat grafts are commonly used in plastic surgery, but their unpredictable absorption rates are a considerable disadvantage. Furthermore, no agreement has been reached regarding the method that best enables fat graft survival. This study aimed to evaluate the effects of different preparation methods on fat graft viability. Fat tissue was harvested from the remnants of transverse rectus abdominis musculocutaneous (TRAM) flaps by syringe aspiration. Harvested fat tissue was prepared using three different methods: centrifugation, metal sieve concentration, and cotton gauze concentration. To evaluate the viabilities of fat cells, XTT assays were performed. For the study, 18 nude mice were allocated to three groups: the centrifugation, metal sieve, and cotton gauze groups (6 mice per group). Prepared fat (1 ml) was injected into the nuchal area of the mice, and 12 weeks later, grafts were dissected to determine graft survival rates and subjected to histologic analysis. No significant differences were observed in graft survival rates and histologic findings (necrosis and vascularity) between the three groups. However, histologic analysis found the metal sieve group to have significantly lower fat cell viability and more inflammation than the other two groups. The findings suggest that the closed centrifugation technique has no advantage over the open cotton gauze technique in terms of fat graft viability, and that the metal sieve concentration method is deficient as a preparation method because it can cause grafted fat degradation.