Fortified Donor-Acceptor Spectral Overlap Facilitated Fluorescence Quenching Efficiency for Developing Sensitive Nanometal Surface Energy Transfer-Based Immunochromatographic Test Strips.

Constructing a fluorescence quenching immunochromatography test strip (FQ-ICTS) is conducive to sensitive point-of-care testing, yet inefficient quenching efficiency (QE) confines the progress of the FQ-ICTS. Herein an innovative nanometal surface energy transfer (NSET)-based FQ-ICTS with magnificent QE was proposed for the highly sensitive detection of T2 toxin utilizing time-resolved fluorescent microspheres (TRFMs) conjugated with T2-BSA as donors and monoclonal antibodies (mAbs) labeled with spherical and flower-shaped gold particles (AuNPs) as acceptors. As the key to biosensors, by regulating the distinct absorption wavelengths of AuNPs-mAb (520-605 nm), the effect of the donor-acceptor overlapping area on the QE was explored, and the NEST pair with the highest QE was screened out to achieve perfect sensitivity.

A broad-spectrum antibody-based lateral flow immunoassay for detection of carbofuran and 3-hydroxy-carbofuran.

Simultaneous detection of carbofuran (CBF) and 3-hydroxy carbofuran (3-OH-CBF) in fruits and vegetables is important due to their high toxicity and widespread use in pest control. However, most lateral flow immunoassay (LFA) approaches only detection CBF. To overcome this limitation, two haptens, 6-((2,2-dimethyl-2,3-dihydrobenzofuran-7-yl)oxy)hexanoic acid and 6-((((2,2-dimethyl-2,3-dihydroben zofuran-7-yl)oxy)carbonyl)amino)hexanoic acid, named H1 and H2, were designed for broad-spectrum antibody detection of CBF and 3-OH-CBF.

Functional peptide conjugated ordered gold nanoparticles based rational electrochemical immunosensor for highly stable and selective detection of zearalenone.

To integrate antifouling properties and good sensitivity on the sensing interface can improve the applicability of an electrochemical immunosensor. These functional regions can be integrated into a single functional peptide (functPP). The rational designed three domains in functPP were the anchoring, antifouling and gold nanoparticles (AuNPs) recognizing domains.

Nanometal surface energy transfer-based lateral flow immunoassay for T2 toxin detection.

In this study, we incorporated nanometal surface energy transfer (NSET) in lateral flow immunoassay (LFIA) and explored the relationship between fluorescence quenching efficiency and detection sensitivity to improve sensitivity of NSET-LFIA system. We developed nine gold nanoparticles (GNPs) with absorption spectrum in the range of 520-605 nm as acceptors and quantum dot microspheres (QDMs) with emission spectrum of 530, 570, and 610 nm as donors. By analyzing the overlap integral area, fluorescence quenching efficiency, and detection sensitivity of 27 donor-acceptor pairs, we observed that the larger overlap integral area led to higher fluorescence quenching efficiency and detection sensitivity.

Production of monoclonal antibody against tylosin and tilmicosin with homogeneous cross-reactivity and its application in lateral flow immunoassay.

To avoid false negative results due to the low cross-reactivity rate (CR) in rapid immunoassay, a group-specific antibody with homogeneous CR toward target compounds is needed for accuracy. In this study, tylosin (TYL) and tilmicosin (TM) were selected as model molecules. Firstly, two-dimensional similarity, electrostatic potential energy, spatial conformation and charge distribution of the haptens TYL-CMO, TYL-6-ACA, TYL-4-APA, TYL-CHO and DES-CMO and target compounds of TYL and TM were obtained using Gaussian 09W and Discovery Studio.

Development of a monoclonal antibody-based lateral flow immunoassay for the detection of benzoic acid in liquid food.

To monitor benzoic acid (BA) residues in liquid food samples, a monoclonal antibody (mAb)-based lateral flow immunoassay (LFA) was developed in this study. First, 2-aminobenzoic acid (2-AA), 3-aminobenzoic acid (3-AA), and 4-aminobenzoic acid (4-AA) were conjugated to BSA and used as immunogens. After cell fusion, mAb 6D8 from 4-AA-BSA performed best with an IC value of 0.

Development of a Lateral Flow Immunoassay Based on a Highly Specific Monoclonal Antibody To Detect 4-Methylaminoantipyrine.

To avoid false-positive results in immunoassays due to cross-reactivity of antibodies with structural analogues, especially metabolites of target compounds, the preparation of highly specific antibodies is crucial. Preserving the characteristic structure of a target compound when designing a hapten is important when preparing highly specific antibodies. Here, we designed a novel hapten, 4-(((1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1-pyrazol-4yl)amino)methyl)benzoic acid, named AA-BA, to improve the specificity of antibodies for detection of 4-methylaminoantipyrine (MAA), a residual marker of dipyrone, an important antipyretic-analgesic and anti-inflammatory drug.

A highly sensitive lateral flow immunoassay based on a group-specific monoclonal antibody and amorphous carbon nanoparticles for detection of sulfonamides in milk.

To meet high-throughput screening of the residues of sulfonamides (SAs) with high sensitivity toward sulfamethazine (SM2) in milk samples, a new highly sensitive lateral flow immunoassay (LFA) based on amorphous carbon nanoparticles (ACNs) was developed. First, a group-specific monoclonal antibody 10H7 (mAb 10H7) that could recognize 25 SAs with high sensitivity toward SM2 (IC value of 0.18 ng/mL) was prepared based on H1 as an immune hapten and H4 as a heterologous coating hapten.

Production of high-affinity monoclonal antibody and development of immunoassay for 3-methyl-quinoxaline-2-carboxylic acid detection in swine muscle and liver.

Production of high-affinity and specific antibodies to small molecules with molecular weight (MW) lower than 200 Da is challenging. Here, we designed a novel hapten, named hapten H6, for the detection of 3-methyl-quinoxaline-2-carboxylic acid (MQCA, MW of 189 Da), a residual marker of olaquindox, one of important veterinary antibiotics. The hapten H6 maintained all structural features of MQCA, especially in mulliken atomic charge distribution.

Peptide amphiphile inspired self-assembled, ordered gold nanocomposites for improved sensitivity of electrochemical immunosensor: Applications in determining the total aflatoxin amount in food stuffs.

In peptide amphiphile, The positively charged amino acid arginine can inspire the ordered self-assembly of gold nanocomposites (AuNPs), transfer positive charge to AuNPs, and weaken the aggregation of AuNPs by electrostatic repulsion, whereas hydrophobic fatty acid chains regulate the self-assembly of AuNPs through hydrophobic interaction, which may be a novel strategy to overcome disordered arrangement and aggregation of AuNPs to obtain an ultra-sensitive electrochemical immunosensor for determining the total aflatoxin amount. In this study, a peptide amphiphile (C14R5), composed of five arginine residues as the hydrophilic chain and myristic acid as the hydrophobic chain, inspired AuNPs to form monodispersed hollow raspberry-like AuNPs (rasAuNPs). rasAuNPs could captured and immobilized large amounts of aflatoxin antigens via the Au-S bonds, resulting in binding to more anti-aflatoxin antibodies.

Development of a New Monoclonal Antibody against Brevetoxins in Oyster Samples Based on the Indirect Competitive Enzyme-Linked Immunosorbent Assay.

The consumption of shellfish contaminated with brevetoxins, a family of ladder-frame polyether toxins formed during blooms of the marine dinoflagellate , can cause neurotoxic poisoning, leading to gastroenteritis and neurotoxic effects. To rapidly monitor brevetoxin levels in oysters, we generated a broad-spectrum antibody against brevetoxin 2 (PbTx-2), 1 (PbTx-1), and 3 (PbTx-3) and developed a rapid indirect competitive enzyme-linked immunosorbent assay (icELISA). PbTx-2 was reacted with carboxymethoxylamine hemihydrochloride (CMO) to generate a PbTx-2-CMO hapten and reacted with succinic anhydride (HS) to generate the PbTx-2-HS hapten.

An ultrasensitive, homogeneous fluorescence quenching immunoassay integrating separation and detection of aflatoxin M based on magnetic graphene composites.

A homogeneous fluorescence quenching immunoassay is described for simultaneous separation and detection of aflatoxin M (AFM) in milk. The novel assay relies on monoclonal antibody (mAb) functionalized FeO decorated reduced-graphene oxide (rGO-FeO-mAb) as both capture probe and energy acceptor, combined with tetramethylrhodamine cadaverine-labeled aflatoxin B (AFB-TRCA) as the energy donor. In the assay, AFB-TRCA binds to rGO-FeO-mAb in the absence of AFM, quenching the fluorescence of TRCA by resonance energy transfer.

Design and study of lipopeptide inhibitors on preventing aggregation of human islet amyloid polypeptide residues 11-20.

Type 2 diabetes mellitus, a kind of conformational disease, has become an epidemic disease, which seriously endangers the quality of life and health of human beings. The deposition of human islet amyloid polypeptide (hIAPP) has been considered as one of the major pathological features of type 2 diabetes mellitus. As lipopeptides have some hydrophobic groups, which are similar to the reported aggregation inhibitors, and some lipopeptides could prevent cells from depositing of amyloid fibrils, several potential lipopeptide inhibitors have been engineered and synthesized, which have been assessed for their inhibitory effect in preventing amyloid fibrils formation of hIAPP by using the conventional thioflavin-T fluorescence assay and new technique microscale thermophoresis (MST).

New peptide inhibitors modulate the self-assembly of islet amyloid polypeptide residues 11-20 in vitro.

The structural transition and misfolding of human islet amyloid polypeptide may cause a common metabolic disease Type 2 diabetes mellitus. Seventeen peptides have been synthesized, possessing different lengths, compositions, and peptide conformation. In this study, the mechanism of these peptides on inhibiting the formation of hIAPP amyloid fibrils was investigated using a conventional ThT fluorescence assay and microscale thermophoresis.

New insights into side effect of solvents on the aggregation of human islet amyloid polypeptide 11-20.

The formation of highly ordered fibrils for the human islet amyloid polypeptide (hIAPP) is considered as one of the precipitating factors of type 2 diabetes mellitus. In this study, an emerging new approach microscale thermophoresis and conventional ThT fluorescence assay were utilized to investigate the aggregation behavior of hIAPP(11-20), giving a new insight of the solvent effect on the aggregation of hIAPP(11-20). hIAPP(11-20) displayed different aggregation behaviors in various buffers, revealing that hIAPP(11-20) not only self-aggregates but also binds to solvent components.

Activity of a novel-designed antimicrobial peptide and its interaction with lipids.

A new antimicrobial peptide l-RW containing double amphipathic binding sequences was designed, and its biological activities were investigated in the present study. L-RW showed antibacterial activity against several bacterial strains but low cytotoxicity to mammalian cells and low hemolytic activity to red blood cells, which makes it a potential and promising peptide for further development. Microscale thermophoresis (MST), a new technique, was applied to study the antimicrobial peptide-lipid interaction for the first time, which examined the binding affinities of this new antimicrobial peptide to various lipids, including different phospholipids, mixture lipids and bacterial lipid extracts.

A novel method for the study of molecular interaction by using microscale thermophoresis.

The fundamental studies for the binding events of protein and its partner are crucial in drug development. In this study, a novel technology named microscale thermophoresis (MST) was applied in the investigation of molecular interaction between an organic dye fluorescein isothiocyanate (FITC) and bovine serum albumin (BSA), and the results were compared with those obtained from conventional fluorescence spectroscopy. The MST data demonstrated that with a short interaction time, FITC showed a high binding affinity for BSA by weak interaction instead of labeling the protein.