Fluorescence Experiments Research Articles

Epigallocatechin Gallate with Potent Anti-Helicobacter pylori Activity Binds Efficiently to Its Histone-like DNA Binding Protein.

Helicobacter pylori (H. pylori)—a human gastric pathogen—forms a major risk factor for the development of various gastric pathologies such as chronic inflammatory gastritis, peptic ulcer, lymphomas of mucosa-associated lymphoid tissues, and gastric carcinoma. The complete eradication of infection is the primary objective of treating any H. pylori-associated gastric condition. However, declining eradication efficiencies, off-target effects, and patient noncompliance to prolong and broad-spectrum antibiotic treatments has spurred the clinical interest to search for alternative effective and safer therapeutic options. As natural compounds are safe and privileged with high levels of antibacterial-activity, previous studies have tested and reported a plethora of such compounds with potential in vitro/in vivo anti-H. pylori activity. However, the mode of action of majority of these natural compounds is unclear. The present study has been envisaged to compile the information of various such natural compounds and to evaluate their binding with histone-like DNA-binding proteins of H. pylori (referred here as Hup) using in silico molecular docking-based virtual screening experiments. Hup—being a major nucleoid-associated protein expressed by H. pylori—plays a strategic role in its survival and persistent colonization under hostile stress conditions. The ligand with highest binding energy with Hup—that is, epigallocatechin-(−)gallate (EGCG)—was rationally selected for further computational and experimental testing. The best docking poses of EGCG with Hup were first evaluated for their solution stability using long run molecular dynamics simulations and then using fluorescence and nuclear magnetic resonance titration experiments which demonstrated that the binding of EGCG with Hup is fairly strong (the resultant apparent dissociation constant (kD) values were equal to 2.61 and 3.29 ± 0.42 μM, respectively).

Modeling Nucleation and Kinetics of Clathrin Assembly by Membrane Localization

The formation of clathrin lattices on the plasma membrane of cells is a multi-component assembly process in the time order of seconds to minutes, which plays an essential role in transport across the membrane. Recent in vitro fluorescence experiments have measured the kinetics of adaptor-mediated clathrin assembly on membranes. Here we develop a microscopic model that can quantitatively reproduce these in vitro kinetics, establishing how cooperativity due to both 2D membrane localization and adaptor protein interactions are necessary to drive the nucleation and growth of clathrin cages. This model is also consistent with the known biochemistry of interactions between clathrin and adaptor proteins, clathrin-clathrin interactions, and the effect of adaptor proteins in strengthening clathrin-clathrin interactions. It explicitly accounts for the multi-valency of the clathrin-clathrin contacts, and the necessary conversion factor between 3D binding rates and 2D rates. We simulated this model using the structure-resolved reaction-diffusion simulator NERDSS, collecting minutes-long time-dependent data and movies of the clathrin assembly on the membrane. We then show how changing the stickiness of the membrane controls the nucleation of clathrin-coated structures on the surface, with clathrin present now at physiologic concentrations. with this model, we can predict how tuning the stoichiometry of components and cargo will impact the nucleation and stability of clathrin cages on the membrane, resulting in productive or abortive assembly events. This quantitative model and corresponding space- and time-dependent simulations provide a critical quantitative framework for investigating how the selection of cargo at the membrane by associated adaptors controls the speed and success of vesicle formation.

Counting Fluorophores and Finding Potentials from FRET, Bayesian Nonparametrics for Challenging Problems in Biophysics

Fluorescence spectroscopy is a great way to reveal complex interactions at the molecular level, but because fluorophores are much smaller than the diffraction limit of light, one bright spot may contain many fluorescently labeled biomolecules. One technique to quantify the number of molecules within a diffraction limited spot is to illuminate the spot, putting the fluorophores into their fluorescently active bright states, then to watch for steplike brightness drops as the fluorophores photobleach one-by-one. This analysis is impeded by detector noise, shot noise, and by the fact that fluorophores can have dark states and multiple bright states. Furthermore, because the number of fluorophores is unknown, we cannot utilize traditional Bayesian methods to count and we must invoke new methods to solve the problem. Here we use Bayesian nonparametric (BNP) tools, that are necessary as the number of fluorophores is unknown, to solve the counting problem. We conclude that our method allows us to count upwards of 100 fluorophores. Single molecule Forster resonance energy transfer (FRET) based fluorescence experiments are a useful way to probe configuration dynamics of molecules based on the distance between donor and acceptor labels. Here we show that we can use single photon information to extract potential profiles from molecules of interest. We do so using Gaussian processes, a powerful tool within BNPs

Different Aggregation Pathways and Structures for Aβ40 and Aβ42 Peptides.

Self-aggregation of amyloid-β (Aβ) peptides has been known to play a vital role in the onset stage of neurodegenerative diseases, indicating the necessity of understanding the aggregation process of Aβ peptides. Despite previous studies on the aggregation process of Aβ peptides, the aggregation pathways of Aβ isoforms (i.e., Aβ40 and Aβ42) and their related structures have not been fully understood yet. Here, we study the aggregation pathways of Aβ40 and Aβ42, and the structures of Aβ40 and Aβ42 aggregates during the process, based on fluorescence and atomic force microscopy (AFM) experiments. It is shown that in the beginning of aggregation process for both Aβ40 and Aβ42, a number of particles (i.e., spherical oligomers) are formed. These particles are subsequently self-assembled together, resulting in the formation of different shapes of amyloid fibrils. Our finding suggests that the different aggregation pathways of Aβ isoforms lead to the amyloid fibrils with contrasting structure.

PTX3 promotes proliferation, invasion and drug resistance of neuroblastoma cells in children by regulating TLR4/NF-κB signaling pathway

Objective: To investigate the effect of pentraxin 3 (PTX3) on the proliferation, invasion and drug resistance of pediatric neuroblastoma cells and its mechanism. Methods: si-RNA (si-RNA group), si-PTX3 (si-PTX3 group), siRNA+ pcDNA3.1 (siRNA+ pcDNA3.1 group), si-PTX3+ pcDNA3.1 (si-PTX3+ pcDNA3.1 group), siRNA+ pcDNA3.1-Toll-like receptor 4 (siRNA+ pcDNA3.1-TLR4 group) and si-PTX3+ pcDNA3.1-TLR4 (si-PTX3+ pcDNA3.1-TLR4 group) were transfected into SH-SY5Y cells. Collected 32 cases of tumor tissue and cancerous tissue in children with childhood neuromaternal cells who were treated at Zhumadian center hospital from July 2016 to August 2019. Real-time fluorescent quantitative polymerase chain (RT-qPCR) reaction and immunohistochemistry experiments were used to detect the protein expressions of PTX3 in neuroblastoma tissues and normal tissues. 5-Ethynyl-2'-deoxyuridine (EdU) was used to detect the proliferation effect of PTX3 on neuroblastoma cell SH-SY5Y. Western blot experiment was used to detect the protein expression levels of vascular endothelial growth factor (VEGF), resistance-related proteins including P-glycoprotein (P-gp) and multidrug resistance-associated protein 1 (MRP-1), and invasion-related protein matrix metalloproteinase-1 (MMP-1). Results: PTX3 mRNA expressions in neuroblastoma tissues were 0.87±0.07, higher than 0.13±0.06 of normal tissues, and the differences were statistically significant (P<0.05), The expression of the immunohistochemistry test PTX3 protein was consistent with the qRT-PCR results. Compared with the si-RNA group (0.95±0.08; 1.02±0.10), the mRNA and protein expressions of PTX3 in the si-PTX3 group (0.25±0.05; 0.45±0.66) decreased, the differences were statistically significant (all P<0.05). The number of EdU positive cells, invasion rate, VEGF, MMP-1, P-gp and MRP-1 protein expressions in si-RNA group were (31.86±1.86)%, (28.12±2.96)%, (0.58±0.07), (0.44±0.06), (0.46±0.08) and (0.51±0.05), respectively, higher than (19.73±1.22)%, (8.45±1.06)%, (0.25±0.05), (0.19±0.03), (0.19±0.06) and (0.16±0.07) in si-PTX3 group, and the differences were statistically significant (all P<0.05). The Number of EdU positive cells [(19.49±1.68)%], invasion rate [(8.48±1.36)%], VEGF protein expression (0.10±0.15), P-gp (0.18±0.07) , TLR4 (0.45±0.06), p-p65 (0.25±0.05) protein expressions in si-PTX3+ pcDNA3.1 group were relatively lower compared with siRNA+ pcDNA3.1 group [(38.21±2.67)%, (26.39±2.14)%, 0.49±0.05, 0.52±0.06, 0.93±0.14 and 0.82±0.06] (all P<0.05). The number of EdU-positive cells [(62.73±5.18)%], invasion rate [(50.45±3.25)%], VEGF protein expression (2.17±0.17), P-gp (2.15±0.16), TLR4 (2.68±0.16), p-p65 (2.48±0.13) protein expressions in the siRNA+ pcDNA3.1-TLR4 group increased compared with siRNA+ pcDNA3.1 group (all P<0.05). Conclusions: Inhibition of PTX3 can inhibit the proliferation and invasion of neuroblastoma cells SH-SY5Y, and reduce drug resistance. Its mechanism may be achieved by regulating the TLR4/NF-κB signaling pathway. This result can provide a new perspective for pediatric neuroblasts tumor diagnosis and clinical treatment.

Complementary leucine zippering system for effective intracellular delivery of proteins by cell-penetrating peptides

A heterodimeric leucine zipper composed of a pair of leucine zipper peptides containing acidic or basic amino acid residues at appropriate positions in each peptide was used as a molecular glue to connect protein cargos to a cell-penetrating peptide (CPP) carrier. To investigate the hybridization properties by fluorescence experiments, we prepared an enhanced green fluorescent protein (EGFP) fused with an acidic leucine zipper (LzK), EGFP-LzK, and a basic leucine zipper (LzE) modified with a CPP, LzE-CPP. The LzK and LzE formed a 1:1 hybrid when EGFP-LzK and LzE-CPP were mixed in phosphate buffer saline, thereby conjugating the EGFP with the CPP. The formation of the 1:1 hybrid was confirmed by fluorescence spectra and fluorescence titration curves. Results from fluorescence microscopy experiments showed that EGFP was successfully delivered into cells by conjugating with the CPP via formation of the LzK/LzE hybrid. We also fused the apoptotic protein p53 with LzK (p53-LzK) and investigated the inhibition of cell proliferation of various cell lines by incubation with the p53-LzK/LzE-CPP hybrid. This hybrid was found to localize in nuclei and successfully inhibited cell-specific proliferation. The LzE/LzK zipper system inhibited cell proliferation more efficiently than the directly fused conjugate, p53-CPP. Our method will be a useful drug delivery system for delivering bioactive proteins to treat various diseases.

Visible‐Light‐Promoted Switchable Synthesis of C‐3‐Functionalized Quinoxalin‐2(1H)‐ones

AbstractA visible‐light‐promoted synthesis of quinoxalin‐2(1H)‐ones has been developed using 9‐mesityl‐10‐methylacridinium perchlorate as an organo‐photocatalyst. The atmosphere‐controlled method (Ar/air) enabled the selective synthesis of hydroxyl‐ and acyl‐containing quinoxalin‐2(1H)‐ones under mild reaction conditions without the use of any metal catalysts or toxic reagents. A fluorescent labelling experiment showed that hydroxyl‐containing quinoxalin‐2(1H)‐ones may have utility in various biological applications as potent fluorophores.magnified image

Investigation on the binding interaction of rhodamine B with human serum albumin: effect of metal ions

The binding of rhodamine B (RB) to human serum albumin (HSA) in the absence and presence of Cu2+ or Fe3+ under simulated physiological conditions was studied by using various biophysical methods for the first time. The results showed that the interaction between HSA and RB could spontaneously result in the formation of HSA-RB complex (namely, static quenching mechanism) through hydrophobic interactions and hydrogen bonds irrespective of the absence or presence of metal ions. The presence of metal ions led to the reduction of binding affinity of RB to HSA compared with no metal ions, which might result from the conformational change of HSA caused by the binding of metal ions. Furthermore, the analysis of UV-vis absorption, circular dichroism, synchronous fluorescence and three-dimensional fluorescence experiments demonstrated that the addition of RB induced conformational and microenvironmental changes of HSA without and with metal ions. In short, this work will be helpful to in-depth understand the transport mechanism and biological effect of RB and the effect of metal ions on the interaction of HSA-RB in vivo.

Protective effects of three structurally similar polyphenolic compounds against oxidative damage and their binding properties to human serum albumin

Brazilin (Bra), hematoxylin (Hto) and hematein (Hte) are structurally similar polyphenols having rich biological activities, but their antioxidant ability has not been well studied. Here, their protective ability against human serum albumin (HSA) oxidative degradation were investigated using 2,2′-Azobis (2-methylpropionamidine) dihydrochloride (AAPH), NaClO and Fenton like reactions methods. The results indicated that polyphenols inhibited the oxidative injuries of HSA in the order: Hto > Bra > Hte. Additionally, the biological effects of polyphenols were mostly influenced by their binding to protein. Therefore, the structure-affinity relationships of polyphenols binding to HSA were also explored. Fluorescence experiments indicated that polyphenols bound to HSA through static quenching mechanism. Furthermore, some conformational changes of HSA could be observed in the presence of polyphenols. Altogether, molecular structure of polyphenols played a significant role in their protective effect against HSA oxidative damage and binding ability, which provided fundamental insights into their application as health care foods.

Green synthesis of platinum nanoclusters using lentinan for sensitively colorimetric detection of glucose

The sensitive colorimetric detection of glucose using nanomaterials has been attracting considerable attention. To improve the detection sensitivity, highly stable lentinan stabilized platinum nanoclusters (Pt-LNT NCs) were prepared, in which lentinan was employed as a mild reductant and stabilizer. The size of platinum nanoclusters (Pt NCs) was only 1.20 ± 0.29 nm. Pt-LNT NCs catalyzed the oxidation of substrate 3,3′,5,5′-tetramethylbenzidine (TMB) in the presence of hydrogen peroxide (H2O2) to produce a blue oxidation product with absorption peak at 652 nm, indicating their peroxidase-like properties. Their enzymatic kinetics followed typical Michaelis-Menten theory. In addition, fluorescence experiments confirmed their ability to efficiently catalyze the decomposition of H2O2 to generate •OH, which resulted in the peroxidase-like mechanism of Pt-LNT NCs. Moreover, a colorimetric method for highly selective and sensitive detection of glucose was established by using Pt-LNT NCs and glucose oxidase. The linear range of glucose detection was 5–1000 μM and the detection limit was 1.79 μM. Finally, this method was further used for detection of glucose in human serum and human urine. The established colorimetric method may promote the development of biological detection and environmental chemistry in the future.

Cd-Based Metal-Organic Framework for Selective Turn-On Fluorescent DMSO Residual Sensing.

Dimethyl sulfoxide (DMSO) is a universally used solvent in various synthetic reactions, and trace amounts of DMSO residual are often seen on the surface of chemical product. It is difficult to quickly determine whether the residual DMSO is washed completely. This work reports a CdII metal-organic framework (MOF) SXU-4 which can detect trace amounts of DMSO in various solvents. Fluorescence experiments reveal its turn-on fluorescence effect toward DMSO with high selectivity and sensitivity, indicating that it can be used as an effective luminescent probe for rapid chemical product purity detection by testing the washing solution. Crystallographically characterized DMSO loaded SXU-4 (DMSO@SXU-4), in combination with computational results uncover that the enhanced DMSO-MOF conjugation through multiple DMSO-MOF supramolecule interactions and charge rearrangement are the main causes of fluorescence intensification.

Synthesis and preliminary evaluation of a PET-FI bimodal imaging agent targeting estrogen receptor

Estrogen receptor is an attractive target for the diagnosis and treatment of breast cancer. This article reports for the first time a dual-modality imaging agent targeting estrogen receptor that can use PET imaging to diagnose breast cancer and utilize fluorescence imaging to achieve intraoperative navigation. Fluorescence experiments show that [natGa] 1 has typical aggregate induced emission characteristics. Above the critical concentration, [natGa] 1 can form biocompatible nanomicelles. [natGa] 1 can quickly light up estrogen receptor positive MCF-7 cells. Cell uptake experiments show that [68Ga] 1 is mediated by estrogen receptor. Therefore, [nat/68Ga] 1 shows the characteristics of highly sensitive diagnosis and visualization of breast cancer, and can be used as a lead compound for the development of a novel PET-FI bimodal imaging agent targeting the estrogen receptor.

Demonstration of Selective Single-Barium Ion Detection with Dry Diazacrown Ether Naphthalimide Turn-on Chemosensors.

Single-molecule fluorescence imaging (SMFI) of gas-phase ions has been proposed for "barium tagging," a burgeoning area of research in particle physics to detect individual barium daughter ions. This has potential to significantly enhance the sensitivity of searches for neutrinoless double-beta decay (0νββ) that is obscured by background radiation events. The chemistry required to make such sensitive detection of Ba2+ by SMFI in dry Xe gas at solid interfaces has implications for solid-phase detection methods but has not been demonstrated. Here, we synthesized simple, robust, and effective Ba2+-selective chemosensors capable of function within ultrapure high-pressure 136Xe gas. Turn-on fluorescent naphthalimide-(di)azacrown ether chemosensors were Ba2+-selective and achieved SMFI in a polyacrylamide matrix. Fluorescence and NMR experiments supported a photoinduced electron transfer mechanism for turn-on sensing. Ba2+ selectivity was achieved with computational calculations correctly predicting the fluorescence responses of sensors to barium, mercury, and potassium ions. With these molecules, dry-phase single-Ba2+ ion imaging with turn-on fluorescence was realized using an oil-free microscopy technique for the first time-a significant advance toward single-Ba2+ ion detection within large volumes of 136Xe, plausibly enabling a background-independent technique to search for the hypothetical process of 0νββ.

Glutathione sensitive vesicles prepared from supramolecular amphiphiles.

Glutathione (GSH) sensitive vesicles were prepared by the self-assembly of amphiphilic inclusion complexes. These novel chemically sensitive supramolecular amphiphiles are anticipated to have applications in drug delivery; the nanocarriers can protect the encapsulated cargo and release it via triggered degradation in high concentrations of GSH. Additionally, the sensitivity of the vesicles to GSH indicates that the dynamic covalent disulfide bond at the vesicle surface can be used for post-modification of the nanocarrier via a thiol-disulfide exchange, a strategy that can be exploited to introduce targeting moieties to increase treatment specificity. Supramolecular amphiphiles containing a dynamic covalent disulfide bond were prepared via the host-guest inclusion complexes between alkylated β-cyclodextrin (β-CD) hosts and adamantane terminated polyethylene glycol derivatives. The significant difference between the critical micelle concentrations of the supramolecular amphiphiles and the individual host and guest components confirmed that a unique supramolecular amphiphile was formed. Fluorescence experiments and dynamic light scattering (DLS) revealed that the supramolecular amphiphiles self-assembled into vesicles of 130 nm diameter which were stable for 8 months. Degradation of the vesicles after incubation with GSH was monitored using DLS and by the release of encapsulated 5,6-carboxyfluorescein (CF), observed by an increase in fluorescence intensity. Degradation of the nanocarrier was faster at intracellular GSH concentrations than at extracellular GSH concentrations.

Silica-Coated Fe3O4 Nanoparticles as a Bifunctional Agent for Magnetic Resonance Imaging and ZnII Fluorescent Sensing.

Bifunctional magnetic/fluorescent core-shell silica nanospheres (MNPs) encapsulated with the magnetic Fe3O4 core and a derivate of 8-amimoquinoline (N-(quinolin-8-yl)-2-(3-(triethoxysilyl) propylamino) acetamide) (QTEPA) into the shell were synthesized. These functional MNPs were prepared with a modified stöber method and the formed Fe3O4@SiO2-QTEPA core-shell nanocomposites are biocompatible, water-dispersible, and stable. These prepared nanoparticles were characterized by X-ray power diffraction (XRD), transmission electron microscopy (TEM), thermoelectric plasma Quad II inductively coupled plasma mass spectrometry (ICP-MS), superconducting quantum interference device (SQUID), TG/DTA thermal analyzer (TGA) and Fourier transform infrared spectroscopy (FTIR). Further application of the nanoparticles in detecting Zn2+ was confirmed by the fluorescence experiment: the nanosensor shows high selectivity and sensitivity to Zn2+ with a 22-fold fluorescence emission enhancement in the presence of 10 μM Zn2+. Moreover, the transverse relaxivity measurements show that the core-shell MNPs have T2 relaxivity (r2) of 155.05 mM−1 S−1 based on Fe concentration on the 3.0 T scanner, suggesting that the compound can be used as a negative contrast agent for MRI. Further in vivo experiments showed that these MNPs could be used as MRI contrast agent. Therefore, the new nanosensor provides the dual modality of magnetic resonance imaging and optical imaging.

Loss of bound zinc facilitates amyloid fibril formation of leukocyte-cell-derived chemotaxin 2 (LECT2)

Aggregation of the circulating protein leukocyte-cell-derived chemotaxin 2 (LECT2) causes amyloidosis of LECT2 (ALECT2), one of the most prevalent forms of systemic amyloidosis affecting the kidney and liver. The I40V mutation is thought to be necessary but not sufficient for ALECT2, with a second, as-yet undetermined condition being required for the disease. EM, X-ray diffraction, NMR, and fluorescence experiments demonstrate that LECT2 forms amyloid fibrils in vitro in the absence of other proteins. Removal of LECT2’s single bound Zn2+ appears to be obligatory for fibril formation. Zinc-binding affinity is strongly dependent on pH: 9–13 % of LECT2 is calculated to exist in the zinc-free state over the normal pH range of blood, with this fraction rising to 80 % at pH 6.5. The I40V mutation does not alter zinc-binding affinity or kinetics but destabilizes the zinc-free conformation. These results suggest a mechanism in which loss of zinc together with the I40V mutation leads to ALECT2.

The application of amide units in the construction of neutral functional dyes for mitochondrial staining.

To develop a new class of neutral fluorescent dyes with mitochondrial staining capacity, a series of functional dyes were obtained from Nile Red (2a-e) and coumarin (3a-e) with different amide compounds via Suzuki coupling reactions. The Nile Red derivatives (2a-e) emitted red fluorescence (590-660 nm) and coumarin derivatives (3a-e) showed blue emission (455-490 nm) in organic solvents. In addition, they exhibited high fluorescence quantum yields (0.27-0.98) in organic solvents and excellent photostability (>92%). Moreover, all of them possessed low cytotoxicity. More importantly, Nile Red borate (2) and coumarin borate (3) only accumulated in lipid droplets, while after being modified by different amide compounds, dyes 2a-e and 3a-e could successfully target mitochondria in HeLa cancer cells via confocal fluorescence experiments. This work provides a new strategy for the design of neutral cellular probes for mitochondrial staining.

Intracellular pH – Advantages and pitfalls of surface-enhanced Raman scattering and fluorescence microscopy – A review

The value of pH in various parts of protoplasm can affect nearly all aspects of cell functions. Therefore, the determination of intracellular acid-base features is required in many areas of biological and biochemical studies. Because of a significant scientific importance of in vivo intracellular pH measurements, various groups carried out such experiments. In this review article we describe intracellular pH measurements using two the most sensitive optical spectroscopies: surface-enhanced Raman scattering (SERS) and fluorescence. It is reasonable to present these two techniques in one review article because the experimental approach in Raman and fluorescence experiments is relatively similar. The basic theoretical background explaining the mechanism of operation of fluorescence and SERS sensors are discussed and the motivations to carry out intracellular pH measurements are briefly described. Future perspectives in this field are also discussed.

Interactions and mechanisms of three different element doped carbon dots with DNA

Carbon dots (CDs) have attracted great attention in the field of materials science and biology. In this paper, three kinds of CDs with different doping elements were synthesized by one-step hydrothermal method. The binding modes and binding capacities of ctDNA and carbon dots doped with three different elements were systematically studied by means of multispectral method, melt chain temperature method and viscosity method. Fluorescence experiments have proved that the interaction modes of CDs, N-CDs and N,S-CDs with ctDNA were groove binding, and the binding force was mainly hydrogen bond and van der Waals interaction, accompanied by slight electrostatic force. In the presence of strong electrolytes and denaturants, the groove binding between carbon dots and DNA was weakened. Circular dichroic spectroscopy and FTIR spectroscopy showed that the groove binding of carbon dots and DNA did not significantly change the conformation of DNA. It was worth noting that compared with undoped carbon dots (CDs), doping with nitrogen and sulfur could weaken the groove binding ability of N,S-CDs and ctDNA. However, increasing the surface charge of carbon points could enhance the binding of N-CDs to ctDNA. This conclusion is expected to provide a theoretical reference for the design of targeted carbon dots in the biomedical field in the future.

A Chemosensory Protein Detects Antifeedant in Locust (Locusta migratoria).

Simple SummaryChemosensory proteins (CSPs) in insects are small compact polypeptides which can bind and carry hydrophobic semiochemicals. CSPs distribute in many organs of insect and have multiple functions. In chemosensory system, CSPs are thought to be responsible for detecting chemical signals from the environment. In this study, we proved that LmigCSPIII, a CSP in Locusta migratoria is involved in detecting an antifeedant. LmigCSPIII exhibits high binding affinity to α-amylcinnamaldehyde, a natural compound from non-host plant which was subsequently demonstrated to be an effective antifeedant. Knockdown of LmigCSPIII gene by RNA interference showed reduced sensitivity to α-amylcinnamaldehyde but showed no changes in their physiological development or food consumption. Our findings provided new evidence that CSPs can detect antifeedant in chemosensory system of insects.Chemosensory system is vitally important for animals to select food. Antifeedants that herbivores encounter can interfere with feeding behavior and exert physiological effects. Few studies have assessed the molecular mechanisms underlying the chemoreception of antifeedants. In this study, we demonstrated that a chemosensory protein (CSP) in Locusta migratoria is involved in detecting an antifeedant. This CSP, LmigEST6 (GenBank Acc. No. AJ973420), we named as LmigCSPIII, expressed in sensory organs where chemosensilla are widely distributed. Fluorescent binding experiments indicated that LmigCSPIII exhibits high binding affinity to α-amylcinnamaldehyde (AMCAL), a natural compound from non-host plant. This compound was subsequently demonstrated to be an effective antifeedant to locusts in feeding bioassay. By injection of double-stranded RNA (dsRNA) of LmigCSPIII, we generated LmigCSPIII knockdown locusts. The feeding behaviour assays demonstrated that the LmigCSPIII knockdown locusts had reduced sensitivity to the antifeedant but showed no changes in their physiological development or food consumption. Therefore, we inferred that this chemosensory protein is involved in antifeedant detection.