Peptide-based electrochemical sensor with nanogold enhancement for detecting rheumatoid arthritis.

Rheumatoid arthritis (RA), an autoimmune and chronic inflammatory disorder, is an incurable disease. We developed a peptide-based electrochemical sensor using electrochemical impedance spectroscopy that can be used to detect autoantibodies for RA diagnostics. We first validated that the developed peptide showed high sensitivity and could compliment the current gold standard method of an anti-cyclic citrullinated peptide antibody (anti-CCP) ELISA. The developed peptide can be modified on the nanogold surface of the working electrode of sensing chips through the method of a self-assembling monolayer. The sensing process was first optimized using a positive control cohort and a healthy control cohort. Subsequently, 10 clinically confirmed samples from RA patients and five healthy control samples were used to find the threshold value of the impedance between RA and healthy subjects. Furthermore, 10 clinically confirmed samples but with low values of anti-CCP autoantibodies were used to evaluate the sensitivity of the present method compared to the conventional method. The proposed method showed better sensitivity than the current conventional anti-CCP ELISA method.

Efficient biocatalytic synthesis of nicotinic acid by recombinant nitrilase via high density culture.

The constitutively expression system for P. putida nitrilase was firstly constructed to improve the nicotinic acid production and reduce the production costs. High density culture strategy was employed to enhance the biomass and nitrilase production of recombinant strain. The total nitrilase activity reached up to 654 U·mL-1 without the induction. 541 g·L-1 nicotinic acid was accumulated via fed batch mode of substrate feeding through 290 min of conversion.

Significantly enhanced substrate tolerance of Pseudomonas putida nitrilase via atmospheric and room temperature plasma and cell immobilization.

The objective of the study was to enhance the substrate tolerance of Pseudomonas putida nitrilase via atmospheric and room temperature plasma (ARTP) and cell immobilization. The mutant library was constructed by ARTP and rapidly screened by an OPA-TCA microscale reaction. A mutant strain of mut-D3 was obtained and its optimum substrate concentration was improved to 150mM from 100mM. It could accumulate 189g/L nicotinic acid (NA) from 3-cyanopyridine (3-CP), which was increased by 42% compared with that of wild type (WT). Additionally, composite immobilization of mut-D3 was performed and SA-PVA immobilized cells could catalyze 250mM 3-CP each batch with finally accumulating 346g/L NA, while free cells accumulated 175g/L NA. These results indicated that the free or immobilized catalysts of mut-D3 could serve as a good choice for NA production. This is the first report on mutation breeding of nitrilase-producing microorganisms by ARTP.