T-cell surface generation of dual bivalent, bispecific T-cell engaging, RNA duplex cross-linked antibodies (dbBiTERs) for re-directed tumor cell lysis

BACKGROUND

Genetic engineered Bispecific T-cell engagers (BiTEs) generate potent cytotoxic effects.

METHODS

Alternately, click chemistry engineered, dual specific bivalent Bispecific T-cell engaging antibodies (dbBiTEs) on T-cell surfaces can be generated from parent monoclonal antibodies.

RESULTS

We show the formation of dbBiTEs on the surface of T-cells along with the introduction of complementary 2'-OMe RNA 32-mer oligonucleotides allowing duplex formation between antibodies, designated as dbBiTERs. dbBiTERs generated in solution from anti-CEA and anti-CD3 OKT3 antibodies retained specific binding to CEA positive versus CEA negative cancer cells and to CD3 positive T-cells comparable to dbBiTEs. When T-cells were precoated with dbBiTEs or dbBiTERs and mixed with CEA positive versus CEA negative cancer cells, similar dose dependent and specific cytotoxicity were observed in redirected cell lysis assays. On-cell generated dbBiTERs exerted potent cytotoxic responses against CEA positive targets and were localized at the cell surface by immuno-gold EM. In addition, we demonstrate that target and T-cells, each coated separately with complementary 2'OMe-RNA-linked antibodies can be cross-linked by RNA duplex formation in vitro to generate redirected cell lysis.

CONCLUSION

The facile generation of dbBiTERs with specific cytolytic activity from intact antibodies and their generation on-cell offers a new avenue for antigen specific T-cell therapy.

Improving the Voltammetric Determination of Hg(II): A Comparison Between Ligand-Modified Glassy Carbon and Electrochemically Reduced Graphene Oxide Electrodes

A new thiosemicarbazone ligand was immobilized through a Cu(I)-catalyzed click reaction on the surface of glassy carbon (GC) and electrochemically reduced graphene oxide (GC-ERGO) electrodes grafted with phenylethynyl groups. Using the accumulation at open circuit followed by anodic stripping voltammetry, the modified electrodes showed a significant selectivity and sensibility for Hg(II) ions. A detection limit of 7 nM was achieved with the GC modified electrodes. Remarkably, GC-ERGO modified electrodes showed a significantly improved detection limit (0.8 nM), sensitivity, and linear range, which we attribute to an increased number of surface binding sites and better electron transfer properties. Both GC and GC-ERGO modified electrodes proved their applicability for the analysis of real water samples.

Click chemistry as a tool in biosensing systems for sensitive copper detection

Copper detection for diagnostic purposes is an appealing field due to the important biological role copper plays as a trace metal. A convenient strategy for sensing copper is to utilize its catalytic ability. Therefore, this review summarizes approaches for copper determination by Cu^I-catalyzed azide/alkyne cycloaddition (CuAAC). The concept was introduced in 2006 and all contributions made up to the middle of 2020 are covered in this review. The issue is divided into three categories: electrochemical, visual, and fluorescence-based methods. The advantages, as well as the disadvantages, of every group, are discussed in detail. The methodology which allows for the determination of copper content in water and human biological samples from 5 s up to 48 h without complex instrumentation are discussed. The reported range of limit of detection (LOD) was 0.38 aM-20 μM, with 1-10 nM being the typical range. The most successful strategies involved using DNA chains or enzymes in the sensing systems.

Copper(I)-Catalyzed Click Chemistry as a Tool for the Functionalization of Nanomaterials and the Preparation of Electrochemical (Bio)Sensors

Proper functionalization of electrode surfaces and/or nanomaterials plays a crucial role in the preparation of electrochemical (bio)sensors and their resulting performance. In this context, copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) has been demonstrated to be a powerful strategy due to the high yields achieved, absence of by-products and moderate conditions required both in aqueous medium and under physiological conditions. This particular chemistry offers great potential to functionalize a wide variety of electrode surfaces, nanomaterials, metallophthalocyanines (MPcs) and polymers, thus providing electrochemical platforms with improved electrocatalytic ability and allowing the stable, reproducible and functional integration of a wide range of nanomaterials and/or different biomolecules (enzymes, antibodies, nucleic acids and peptides). Considering the rapid progress in the field, and the potential of this technology, this review paper outlines the unique features imparted by this particular reaction in the development of electrochemical sensors through the discussion of representative examples of the methods mainly reported over the last five years. Special attention has been paid to electrochemical (bio)sensors prepared using nanomaterials and applied to the determination of relevant analytes at different molecular levels. Current challenges and future directions in this field are also briefly pointed out.

Novel electrochemical sensing platform for quantitative monitoring of Hg(II) on DNA-assembled graphene oxide with target recycling

This work designs a new electrochemical sensing platform for the quantitative monitoring of mercury ion (Hg(2+)) on poly-T(15) oligonucleotide-functionalized graphene oxide by coupling with DNase I-assisted target recycling amplification. The assay was carried out on the basis of T-Hg(2+)-T coordination chemistry by using target-induced dissociation of indicator-labeled poly-T(15) oligonucleotide from graphene oxide nanosheets. The electronic signal was amplified through DNase I-triggered target recycling. Experimental results indicated that the amperometric response of DNA-based sensing platform deceased with the increasing Hg(2+) concentration in the sample, and has a detection limit of 0.12nM with a dynamic working range of up to 50nM. Our strategy afforded exquisite selectivity for Hg(2+) against other environmentally related metal ions. More significantly, this methodology displayed high reproducibility and acceptable accuracy, thus representing an optional sensing scheme for the screening of Hg(2+) in environmental water samples.