Green fluorescent protein-labeled recombinant fluobody for detecting the picloram herbicide

Chemically engineered unzipped multiwalled carbon nanotube and rGO nanohybrid for ultrasensitive picloram detection in rice water and soil samples

Picloram (4-Amino-3,5,6-trichloro pyridine-2-carboxylic acid) is a chlorinated herbicide that has been discovered to be tenacious and relatively durable in both soil and water. It is known to have adverse and unpleasant effects on humans causing several health complications. Therefore, the determination of picloram is profoundly effective because of its bio-accumulative and persistent nature. Because of this, a sensitive, rapid, and robust detection system is essential to detect traces of this molecule. In this study, we have constructed a novel nanohybrid system comprising of an UZMWCNT and rGO decorated on AuNPs modified glassy carbon electrode (UZMWCNT + rGO/AuNPs/GCE). The synthesized nanomaterials and the developed system were characterized using techniques such as SEM, XRD, SWV, LSV, EIS, and chronoamperometry. The engineered sensor surface showed a broad linear range of 5 × 10^-2 nM to 6 × 10⁵ nM , a low limit of detection (LOD) of 2.31 ± 0.02 (RSD < 4.1%) pM and a limit of quantification (LOQ) of 7.63 ± 0.03 pM. The response time was recorded to be 0.2 s, and the efficacy of the proposed sensor system was studied using rice water and soil samples collected from the agricultural field post filtration. The calculated recovery % for picloram in rice water was found to be 88.58%-96.70% (RSD < 3.5%, n = 3) and for soil it was found to be 89.57%-93.24% (RSD < 3.5%, n = 3). In addition, the SWV responses of both the real samples have been performed and a linear plot have been obtained with a correlation coefficient of 0.97 and 0.96 for rice and soil samples, respectively. The interference studies due to the coexisting molecules that may be present in the samples have been found to be negligible. Also, the designed sensor has been evaluated for stability and found to be highly reproducible and stable towards picloram detection.

A chimera of green fluorescent protein with single chain variable fragment antibody against ginsenosides for fluorescence-linked immunosorbent assay

A chimera of green fluorescent protein extracted from Aequorea coerulescens (AcGFP), a mutant that has been codon optimized for mammalian expression, with single-chain variable fragment (scFv) antibody against ginsenoside Re (GRe-scFv), named fluobody, has been successfully expressed in Escherichia coli (E. coli) to develop simple, speedy, and sensitive fluorescence-linked immunosorbent assay (FLISA). Two chimera proteins were constructed to contain GRe-scFv at the C-terminus of AcGFP (C-fluobody) and at the N-terminus of AcGFP (N-fluobody). These fluobodies were then purified by ion metal affinity chromatography and refolded by stepwise dialysis. The characterization of both fluobodies revealed that C-fluobody was found to be appropriate probe for FLISA as compare with N-fluobody. Furthermore, improvement of limit of detection (LOD) was observed in FLISA using C-fluobody (10 ng/mL) due to its strong fluorescence intensity of AcGFP compared with conventional enzyme-linked immunosorbent assay (ELISA) using parental monoclonal antibody against ginsenoside Re (G-Re), MAb-4G10 (100 ng/mL). Since some steps required in ELISA can be avoided in this present FLISA, speedy and sensitive immunoassay also could be performed using fluobody instead of monoclonal antibody and scFv.

Transgenic tobacco plants expressing a dimeric single-chain variable fragment (scfv) antibody against Salmonella enterica serotype Paratyphi B

Transgenic tobacco plants were produced that express an anti-Salmonella enterica single-chain variable fragment (scFv) antibody that binds to the lipopolysaccharide (LPS) of S. enterica Paratyphi B. The coding sequence of this scFv was optimized for expression in tobacco, synthesized and subsequently placed behind three different promoters: an enhanced tobacco constitutive ubiquitous promoter (EntCUP4), and single- and double-enhancer versions of the Cauliflower Mosaic Virus 35S promoter (CaMV 35S). These chimeric genes were introduced into Nicotiana tabacum cv. 81V9 by Agrobacterium-mediated transformation and 50 primary transgenic (T(0)) plants per construct were produced. Among these plants, 23 were selected for the ability to express active scFv as determined by enzyme-linked immunosorbent assay (ELISA) using S. enterica LPS as antigen. Expanded bed adsorption-immobilized metal affinity chromatography (EBA-IMAC) was used to purify 41.7 mug of scFv/g from leaf tissue. Gel filtration and surface plasmon resonance (SPR) analyses demonstrated that the purified scFv was active as a dimer or higher-order multimer. In order to identify T(1) plants suitable for development of homozygous lines with heritable scFv expression, kanamycin-resistance segregation analyses were performed to determine the number of T-DNA loci in each T(0) plant, and quantitative ELISA and immunoblot analyses were used to compare expression of active and total anti-Salmonella scFv, respectively, in the T(1) generation. As S. enterica causes millions of enteric fevers and hundreds of thousands of deaths worldwide each year, large-scale production and purification of this scFv will have potential for uses in diagnosis and detection, as a therapeutic agent, and in applications such as water system purification.