Characterization of a Single Chain Fv Antibody that Reacts with Free Morphine

Nanoarchitectonics for Abused-Drug Biosensors

Rapid, accessible, and highly accurate biosensors for the detection of addictive and abused drugs are needed to reduce the adverse personal and societal impacts of addiction. Modern sensors that utilize next-generation technologies, e.g., nanobiotechnology and nanoarchitectonics, have triggered revolutionary progress in the field as they allow accurate detection and tracking of trace levels of major classes of drugs. This paper reviews advances in the field of biosensors for the detection of commonly abused drugs, both prescribed such as codeine and morphine, and illegal narcotics like cocaine.

Systematic Structure-Based Virtual Screening Approach to Antibody Selection and Design of a Humanized Antibody against Multiple Addictive Opioids without Affecting Treatment Agents Naloxone and Naltrexone

Opioid drug use, especially heroin, is known as a growing national crisis in America. Heroin itself is a prodrug and is converted to the most active metabolite 6-monoacetylmorphine (6-MAM) responsible for the acute toxicity of heroin and then to a relatively less-active metabolite morphine responsible for the long-term toxicity of heroin. Monoclonal antibodies (mAbs) are recognized as a potentially promising therapeutic approach in the treatment of opioid use disorders (OUDs). Due to the intrinsic challenges of discovering an mAb against multiple ligands, here we describe a general, systematic structure-based virtual screening and design approach which has been used to identify a known anti-morphine antibody 9B1 and a humanized antibody h9B1 capable of binding to multiple addictive opioids (including 6-MAM, morphine, heroin, and hydrocodone) without significant binding with currently available OUD treatment agents naloxone, naltrexone, and buprenorphine. The humanized antibody may serve as a promising candidate for the treatment of OUDs. The experimental binding affinities reasonably correlate with the computationally predicted binding free energies. The experimental activity data strongly support the computational predictions, suggesting that the systematic structure-based virtual screening and humanization design protocol is reliable. The general, systematic structure-based virtual screening and design approach will be useful for many other antibody selection and design efforts in the future.

Epitope specificity of two anti-morphine monoclonal antibodies: In vitro and in silico studies

Monoclonal antibodies (mAbs) against morphine are important in the development of immunotherapeutic and diagnostic methods for the treatment and prevention of drug addiction. By the surface plasmon resonance (SPR) and enzyme immunoassay techniques, we characterized two previously obtained mAbs 3K11 and 6G1 and showed their ability to recognize free morphine and morphine-containing antigens in different ways because of the epitope specificity thereof. Using the defined amino acid sequences, we obtained three-dimensional models of the variable regions of Fab fragments of these antibodies and compared them with the known sequence and spatial structure of the anti-morphine antibody 9B1. Docking simulations are performed to obtain models of the antibodies complexes with morphine. Differences in the models of 3K11 and 6G1 complexes with morphine correlate with their experimentally detected epitope specificity. The results, in particular, can be used for the structure-based design of the corresponding humanized antibodies. According to our modeling and docking results, the very different modes of morphine binding to mAbs 3K11 and 6G1 are qualitatively similar to those previously reported for cocaine and two anti-cocaine antibodies. Thus, the obtained structural information brings more insight into the hapten recognition diversity.

A gold nanoparticle-single-chain fragment variable antibody as an immunoprobe for rapid detection of morphine by dipstick

Gold nanoparticle (AuNP)-based optical assays are of significant interest since the molecular phenomenon can be examined easily with change in the color of AuNPs. Herein, we report the development of a dipstick using a AuNP-labeled single-chain fragment variable (scFv) antibody for the detection of morphine. The scFv antibodies for morphine were developed using phage display-based antibody library. Immunoglobulin variable regions of heavy (V H)- and light (V L)-chain genes were connected via a glycine-serine linker isolated from murine immune repertoire and cloned into the expression vector pIT2. The scFv was produced in Escherichia coli HB2151, yielding a functional protein with a molecular weight of approximately 32 kDa. The morphine scFv was labeled with gold nanoparticles and used as an optical immunoprobe in a dipstick. The competitive dipstick assay characterized the ability of the scFv antibody to recognize free morphine. The detection range was 1-1000 ng mL-1 with a limit of detection (LOD) of 5 ng mL-1 under optimal conditions, and the IC50 value was 14 ng mL-1 for morphine. The developed optical dipstick kit of scFv antibody was capable of specifically binding to free morphine and its analogs in a solution in less than 5 min and could be useful for on-site screening of a real sample in blood, urine, and saliva.