Monitoring enzymatic degradation of emerging contaminants using a chip-based robotic nano-ESI-MS tool

Recent Advances in the Development of Laccase-Based Biosensors via Nano-Immobilization Techniques

Monitoring phenolic compounds is critical in the environmental, food, and medical sectors. Among many recent advanced detection platforms, laccase-based biosensing platforms gave very rapid, effective, online, and in situ sensing of phenolic compounds. In laccase-based biosensors, laccase immobilization techniques have a vital role. However, a detailing of the advancements in laccase immobilization techniques employed in laccase-based biosensors is lacking in the literature. Thus, in this review, we assessed how the nano-immobilization techniques shaped the laccase biosensing platforms. We discussed novel developments in laccase immobilization techniques such as entrapment, adsorption, cross-linking, and covalent over new nanocomposites in laccase biosensors. We made a comprehensive assessment based on the current literature for future perspectives of nano-immobilized laccase biosensors. We found the important key areas toward which future laccase biosensor research seems to be heading. These include 1. A focus on the development of multi-layer laccase over electrode surface, 2. The need to utilize more covalent immobilization routes, as they change the laccase specificity toward phenolic compounds, 3. The advancement in polymeric matrices with electroconductive properties, and 4. novel entrapment techniques like biomineralization using laccase molecules. Thus, in this review, we provided a detailed account of immobilization in laccase biosensors and their feasibility in the future for the development of highly specific laccase biosensors in industrial, medicinal, food, and environmental applications.

Rapid detection of sulfur mustard hydrolysis products based on microextraction by packed sorbent combined with nano-electrospray ionization mass spectrometry

RATIONALE

Sulfur mustard is a blister agent prohibited by the Chemical Weapons Convention, and the detection of its hydrolysis product, thiodiglycol (TDG), is an important indicator of blister agent contamination. Due to the poor volatility and low extraction efficiency of TDG, derivatization gas chromatography or liquid chromatography is required for conventional methods, and the detection process is cumbersome and time-consuming.

METHODS

A microextraction by packed sorbent (MEPS) device and a nano-electrospray ionization (nano-ESI) device were used. The central composite design (CCD) model of Response Surface Methodology was used to optimize the elution procedure; the variance analysis under equal repeated trials with multiple factors was used to quantitatively analyze the significance of the impact of related factors on the nano-ESI efficiency. The MEPS-nano-ESI-MS experimental conditions were optimized.

RESULTS

A new detection method of sulfur mustard hydrolysis products in water based on MEPS-nano-ESI-MS was established; the detection limit was 1 ng/mL and was linear between 5 ng/mL and 100 ng/mL (R²  = 0.9911) with a precision of ≤7.2%, and the recovery rate was 107.89% when the sample concentration was 40 ng/mL.

CONCLUSIONS

The experimental results showed that the proposed method could quickly detect the contaminated water samples without chromatographic separation and derivatization, thereby verifying the contamination of sulfur mustard on site.

Characterization of free and immobilized laccase from Cyberlindnera fabianii and application in degradation of bisphenol A

Recovery difficulty and inactivation of laccases are major challenges that hamper their application in biotechnology. In this study, laccase was purified from Cyberlindnera fabianii using ion-exchange and gel filtration chromatography with homogeneity confirmed by sodium dodecyl sulphate polyacrylamide gel electrophoresis. Purified laccase of 52 kDa was immobilized on calcium and copper alginate beads by entrapment method. Free and immobilized enzymes were characterized, and efficiency of bisphenol A (BPA) degradation was determined. pH optima for free and immobilized laccases were 5.0 and 6.0, respectively. Ca and Cu alginate immobilized laccase (Ca-AIL and Cu-AIL) had optimum activity at 60 °C and 50 °C, respectively while free laccase (FL) was at 40 °C. K_m and V_max of FL, Ca-AIL and Cu-AIL were 0.032 mM and 15 mM/min, 0.078 mM and 6.98 mM/min, and 0.091 mM and 5.61 mM/min, respectively. Remarkably, immobilized laccases had higher operational stability than FL over 21 d at 4°C. Reusability of immobilized laccase was effective for 3 cycles with residual activity above 70%. Notably, Ca-AIL and Cu-AIL exhibited 71% and 65.5% BPA degradation efficiency on 14 d. Results reveal good kinetic parameters, improved thermal stability and enhanced reusability of immobilized laccase from C. fabianii with potentials for various industrial applications and bioremediation.

Enzymes in removal of pharmaceuticals from wastewater: A critical review of challenges, applications and screening methods for their selection

At present, the removal of trace organic chemicals such as pharmaceuticals in wastewater treatment plants is often incomplete resulting in a continuous discharge into the aqueous environment. To overcome this issue, bioremediation approaches gained significant importance in recent times, since they might have a lower carbon footprint than chemical or physical treatment methods. In this context, enzyme-based technologies represent a promising alternative since they are able to specifically target certain chemicals. For this purpose, versatile monitoring of enzymatic reactions is of great importance in order to understand underlying transformation mechanisms and estimate the suitability of various enzymes exhibiting different specificities for bioremediation purposes. This study provides a comprehensive review, summarizing research on enzymatic transformation of pharmaceuticals in water treatment applications using traditional and state-of-the-art enzyme screening approaches with a special focus on mass spectrometry (MS)-based and high-throughput tools. MS-based enzyme screening represents an approach that allows a comprehensive mechanistic understanding of enzymatic reactions and, in particular, the identification of transformation products. A critical discussion of these approaches for implementation in wastewater treatment processes is also presented. So far, there are still major gaps between laboratory- and field-scale research that need to be overcome in order to assess the viability for real applications.