Determination of the total antioxidant capacity of the Chinese tea based on a novel "peroxidase/zirconium phosphonate"composite electrochemical sensor.

In this work, a novel zirconium phosphonate (ZrPR1R2) was prepared by decorating both the aminoethoxy- group (R1) and the carboxypropyl- group (R2) on the zirconium phosphate layers in order to manipulate further the immobilization of the peroxidase (POD), and an antioxidant biosensor with higher sensitivity was constructed by dropping the POD/ZrPR1R2 composite onto the glassy carbon electrode surface. The activity of the POD/ZrPR1R2 composite was detected by Uv-vis spectra. The direct electrochemical behavior, the electrocatalytic response to dissolved oxygen and hydrogen peroxide, as well as the ability to detect total antioxidant capacity in tea sample were investigated by the methods of cyclic voltammetry. The results indicated that the immobilization of POD in ZrPR1R2 nanosheets matrix enhanced the enzymatic activity, and achieved the fast and direct electron transfer between POD and glassy carbon electrode. Moreover, the POD/ZrPR1R2 composite modified electrode show the electrocatalytic response to hydrogen peroxide in the linear range of 8.8×10-8 to 8.8×10-7 mol L-1, with the detection limit of 3.3×10-8 mol L-1. Attributing to the sensitive response to dissolved oxygen, the total antioxidant capacity can be detected directly in the real tea water by this POD/ZrPR1R2 composite modified electrode.

Green extract rosemary acid as a viscosity-sensitive molecular sensor in liquid systems.

The liquid micro-environment plays a momentous role in the regulation of various activities, and the abnormal changes are often closely related to the deterioration phenomena in multiple beverages. The local viscosity fluctuation has long been regarded as a key indicator to reflect the micro-environmental status changes. Herein, we proposed a versatile optical sensor, rosmarinic acid (RA), one kind of green natural product extracted from rosemary, for monitoring liquid micro-environmental viscosity alterations. RA displays a larger Stokes shift (123.8 nm) with narrow-band energy and exhibits wide adaptability, high selectivity, good sensitivity, and excellent photostability in various commercial liquids. When in high viscous media, a bright fluorescent signal of RA is specifically activated, and a high signal-to-noise ratio signal was released (58-fold). With the assistance of the fluorescence analytical technique, we have successfully achieved tracking the viscosity fluctuations during the deterioration stage of liquids via an in situ and visualization method. Our study will spur additional research on the molecular tools extracted from natural products for liquid safety inspection, and a convenient and sustainable application pathway has been established.

ENERGI-F703 gel, as a new topical treatment for diabetic foot and leg ulcers: A multicenter, randomized, double-blind, phase II trial.

Background: Diabetic foot and leg ulcers are a major cause of disability among patients with diabetes mellitus. A topical gel called ENERGI-F703, applied twice daily and with adenine as its active pharmaceutical ingredient, accelerated wound healing in diabetic mice. The current study evaluated the safety and efficacy of ENERGI-F703 for patients with diabetic foot and leg ulcers. Methods: This randomized, double-blind, multicenter, phase II trial recruited patients from eight medical centers in Taiwan. Patients with intractable diabetic foot and leg ulcers (Wagner Grade 1-3 without active osteomyelitis) were randomly assigned (2:1) to receive topical ENERGI-F703 gel or vehicle gel twice daily for 12 weeks or until complete ulcer closure. The investigator, enrolled patients and site personnel were masked to treatment allocation. Intention to treat (ITT) population and safety population were patient to primary analyses and safety analyses, respectively. Primary outcome was complete ulcer closure rate at the end of treatment. This trial is registered with ClinicalTrials.gov, number NCT02672436. Findings: Starting from March 15th, 2017 to December 26th, 2019, 141 patients were enrolled as safety population and randomized into ENERGI-F703 gel (n = 95) group or vehicle gel (n = 46) group. In ITT population, ENERGI-F703 (n = 90) and vehicle group showed ulcer closure rates of 36.7% (95% CI = 26.75% - 47.49%) and 26.2% (95% CI = 13.86% - 42.04%) with difference of 9.74 % (95 % CI = -6.74% - 26.23%) and 25% quartiles of the time to complete ulcer closure of 69 days and 84 days, respectively. There were 25 (26.3%) patients in ENERGI-F703 group and 11 (23.9%) patients in vehicle group experiencing serious adverse events and five deaths occurred during the study period, none of them related to the treatment. Interpretation: Our study suggests that ENERGI-F703 gel is a safe and well-tolerated treatment for chronic diabetic foot and leg ulcers. Further studies are needed to corroborate our findings in light of limitations. Funding: Energenesis Biomedical Co., Ltd.

Comparison of rhodamine 6G, rhodamine B and rhodamine 101 spirolactam based fluorescent probes: A case of pH detection.

Ring-opening reaction of rhodamine spirolactam has been widely applied to construct fluorescent probes. The fluorescence properties of the probe were finely tuned for specific purpose through changing the rhodamine fluorophore. However, the influence on response range and kinetic parameters of the probe during the change has been seldom discussed. Herein, we took pH detection as an example and constructed spirolactam based probes (RLH A-C) with Rhodamine 6G, Rhodamine B and Rhodamine 101. The pKa values and observed rate constant kobs of RLH A-C were determined and found to negatively correlated with the calculated Gibbs free energy differences ΔGC-O and ΔGTS respectively. The potential applications of RLH A-C in imaging acidic microenvironment were also investigated in cells. We expect the comparison of rhodamine fluorophores will facilitate the quantitative optimization of rhodamine spirolactam based fluorescent probes.

In Situ Functionalization of Silver Nanoparticles by Gallic Acid as a Colorimetric Sensor for Simple Sensitive Determination of Melamine in Milk.

A simple and green colorimetric sensing assay strategy for highly efficient determination of melamine has been fabricated, which is based on the redox reaction of gallic acid with Ag+. Monodispersed Ag nanoparticles (AgNPs) were obtained using gallic acid as a reducing and stabilizing agent. However, the aggregate behavior of AgNPs was observed, while the melamine was present in the reaction medium. As a result, the color of the solution changed from vivid yellow to brown, and the density of the color was quantitatively correlated with the melamine concentration. The aggregation of AgNPs could be attributable to the formation of hydrogen bonds between melamine and gallic acid. The designed sensor exhibited a good detection limit of 0.099 µM (0.012 ppm), which was much lower than the safety limit in China (1.0 ppm) and EU (2.0 ppm). Additionally, the sensing assay displayed good selectivity toward melamine over other coexisting substances. Consequently, the proposed colorimetric sensor was successfully used for the determination of melamine detection in raw milk samples.

Visual detection of viscosity through activatable molecular rotor with aggregation-induced emission.

Food safety has become one of the urgent affairs in the global public health studies, and irregular viscosity is closely associated with the food spoilage extent. In this study, one kind of activatable molecular rotor (TPA-PBZ) based on triphenylamine derivates has been synthesized via the Schiff base condensation reaction. This rotor is comprised by donor-accepter conjugated structure, with aggregation induced-emission feature and a large Stokes shift of 160 nm in water. The rotation of aromatic rings in TPA-PBZ is restricted in high-viscosity microenvironment, with the gradually increasing fluorescence emission signal at 568 nm. Significantly, this rotor TPA-PBZ has successfully been applied not only in the determination of thickening effects of food gum, but also in the detection of viscosity enhancement during the liquid food spoilage process. This molecular rotor can be utilized as an intelligent monitor platform for food quality and safety inspection in viscosity-related conditions.

Arl4D-EB1 interaction promotes centrosomal recruitment of EB1 and microtubule growth.

ADP-ribosylation factor (Arf)-like 4D (Arl4D), one of the Arf-like small GTPases, functions in the regulation of cell morphology, cell migration, and actin cytoskeleton remodeling. End-binding 1 (EB1) is a microtubule (MT) plus-end tracking protein that preferentially localizes at the tips of the plus ends of growing MTs and at the centrosome. EB1 depletion results in many centrosome-related defects. Here, we report that Arl4D promotes the recruitment of EB1 to the centrosome and regulates MT nucleation. We first showed that Arl4D interacts with EB1 in a GTP-dependent manner. This interaction is dependent on the C-terminal EB homology region of EB1 and partially dependent on an SxLP motif of Arl4D. We found that Arl4D colocalized with γ-tubulin in centrosomes and the depletion of Arl4D resulted in a centrosomal MT nucleation defect. We further demonstrated that abolishing Arl4D-EB1 interaction decreased MT nucleation rate and diminished the centrosomal recruitment of EB1 without affecting MT growth rate. In addition, Arl4D binding to EB1 increased the association between the p150 subunit of dynactin and the EB1, which is important for MT stabilization. Together, our results indicate that Arl4D modulates MT nucleation through regulation of the EB1-p150 association at the centrosome.

Systematic study of synthesizing various heteroatom-substituted rhodamines from diaryl ether analogues.

The dye rhodamine, as the most popular scaffold to construct fluorescent labels and probes, has been explored extensively on its structure-fluorescence relationships. Particularly, the replacement of the oxygen atom in the 10th position with heteroatoms obtained various new rhodamines with improved photophysical properties, such as brightness, photostability, red-shifted emission and fluorogenicity. However, the applications of heteroatom-substituted rhodamines have been hindered by difficult synthetic routes. Herein, we explored the condensation strategy of diaryl ether analogues and o-tolualdehyde to synthesize various heteroatom-substituted rhodamines. We found that the electron property and steric effect in the rhodamine 10th position determined the synthetic yield. It's concluded that this condensation method was more suitable for the synthesis of heteroatom-substituted rhodamines with small or electron-donating groups like rhodamine, S-rhodamine and Si-rhodamine. We hope these results will benefit the design and synthesis of heteroatom-substituted rhodamines.

Two-dimensional ß-MoO3@C nanosheets as high-performance negative materials for supercapacitors with excellent cycling stability.

MoO3 has gained a great deal of attention as a promising electrode material in energy storage devices. In particular, the low dimensional MoO3 nanosheets coated with carbon layers are desirable electrode materials in supercapacitors. However, the fabrication or construction of ß-MoO3 with a special morphology is difficult. Here, we report a simple solvothermal treatment method to synthesize two-dimensional ß-MoO3@C (2D ß-MoO3@C) nanosheets. When used as electrode materials for supercapacitors, the as-prepared material displays an ultra-long lifespan with a 94% retention ratio after 50 000 cycles at 2 A g-1. The excellent cycling stability is mainly attributed to the unique 2D nanosheet structure and the presence of the carbon layer on the surface of the nanosheet. Specifically, the presence of the carbon layer increases the electric conductivity of MoO3, which facilitates a good access point for electrolyte ions and short ion diffusion paths. In addition, MoO3 that has been coated with a carbon layer can maintain a good structural stability due to the carbon layer restricting the volume expansion of MoO3 during the charge procedure. We believe that the present work opens a new way for designing the 2D layered materials with unique architectures for supercapacitor applications.

A reporter mouse for non-invasive detection of toll-like receptor ligands induced acute phase responses.

The acute phase response (APR) is a systemic first-line defense against challenges including infection, trauma, stress, and neoplasia. Alteration of acute phase protein (APP) levels in plasma is the most important change during acute phase response. C-reactive protein (CRP), which increases dramatically during inflammation onset, is an indicator of inflammation. To monitor the process of APR, we generated human CRP promoter-driven luciferase transgenic (hCRP-Luc) mice to quantify the hCRP promoter activation in vivo. The naïve female hCRP-Luc mice express low basal levels of liver bioluminescence, but the naïve male hCRP-Luc mice do not. Thus, female hCRP-Luc mice are suitable for monitoring the process of APR. The liver bioluminescence of female hCRP-Luc mice can be induced by several toll-like receptor (TLR) ligands. The expression of liver bioluminescence was highly sensitive to endotoxin stimulation in a dose-dependent manner. On-off-on bioluminescence response was noted in female hCRP-Luc mice upon two endotoxin stimulations one month apart. The LPS-induced bioluminescence of the female hCRP-Luc mice was IL-6-mediated and associated with APP alpha-1-acid glycoprotein expression. In conclusion, the female hCRP-Luc mouse is a non-invasive, sensitive and reusable reporter tool for APR.

A general strategy to develop cell membrane fluorescent probes with location- and target-specific fluorogenicities: a case of a Zn2+ probe with cellular selectivity.

We reported fluorescent probes to image Zn2+ with plasma membrane-specific and Zn2+-specific fluorogenicities. The probes contained hydrophobic alkyl chains as membrane-anchored domains and hydrophilic zinc sensor ZTRS, and aggregated to display quenched fluorescence. Cells dissolved the aggregates and the liberated probes were dispersed on the outside of the cell plasma membrane. Aggregates that did not bind to the cell membrane still exhibited aggregation-induced fluorescence quenching after complexing with zinc ions, while probes anchored on the membrane surface exhibited a fluorescence-enhanced response upon recognition of zinc ions.

[Construction of recombinant PRRSV ORF5 gene by DNA shuffling technique].

Recombinant PRRSV △2ORF5 gene was constructed using DNA shuffling from four genetically different strains of PRRSV to study its heterologous cross-neutralizing ability. The △2ORF5 mutant gene was cloned into the vector pET-32a and transferred into E. coli BL21. SDS-PAGE confirmed that the molecular weight of the recombinant △2ORF5 was about 42 kDa, consistent with the predicted result. Then the purified recombinant protein was injected into BALB/c mouse to obtain polyclonal antibody. Western blotting analysis with mouse-anti-△2ORF5 polyclonal serum indicated that the parental virus recombinant GP5 protein reacted with the specific antibodies. Four parental viruses could be inhibited by the anti-△2ORF5 polyclonal antibody and the inhibition rates were higher than 53%. This work has laid a foundation for further development vaccine for PRRSV.

Complete genomic characterization of two European-genotype porcine reproductive and respiratory syndrome virus isolates in Fujian province of China.

Porcine reproductive and respiratory syndrome (PRRS) is considered one of the most devastating swine diseases worldwide, resulting in immense economic losses. PRRS virus (PRRSV) is divided into two major genotypes, European (type 1) and the North American (type 2). Type 1 PRRSV have recently emerged in Fujian province (South China), and this might have a significant impact on the Chinese pig industry. From 2013 to 2014, two type 1 PRRSV strains, named FJEU13 and FJQEU14, were isolated from piglets and sows with respiratory problems and reproductive disorders in Fujian province. The full genome length of the two isolates was 14,869-15,062 nucleotides (nt), excluding the poly(A) tail. These isolates shared 86.0-89.9% sequence identity with the prototypic strains Lelystad virus (LV) and 82.8-92% with Chinese type 1 PRRSV strains, but only 59.9-60.1% with the North American reference strain VR-2332. However, they were 82.9% identical to each other. Nonstructural protein 2 (Nsp2) and ORF3-ORF5 were the most variable regions when compared to other type 1 PRRSV strains. Nsp2 and ORF3 contained multiple discontinuous deletions and a 204-bp deletion in NSP2 in isolate FJQEU14, which has never been described in other Chinese type 1 PRRSV strains. All of these results might be useful for understanding the epidemic status of type 1 PRRSV in China.

Synthesis of Self-Assembled Spermidine-Carbon Quantum Dots Effective against Multidrug-Resistant Bacteria.

This study reports a two-step method to synthesize spermidine-capped fluorescent carbon quantum dots (Spd-CQDs) and their potential application as an antibacterial agent. Fluorescent carbon quantum dots (CQDs) are synthesized by pyrolysis of ammonium citrate in the solid state and then modified with spermidine by a simple heating treatment without a coupling agent. Spermidine, a naturally occurring polyamine, binds with DNA, lipids, and proteins involved in many important processes within organisms such as DNA stability, and cell growth, proliferation, and death. The antimicrobial activity of the as-synthesized Spd-CQDs (size ≈4.6 nm) has been tested against non-multidrug-resistant E. coli, S. aureus, B. subtilis, and P. aeruginosa bacteria and also multidrug-resistant bacteria, methicillin-resistant S. aureus (MRSA). The minimal inhibitory concentration value of Spd-CQDs is much lower (>25 000-fold) than that of spermidine, indicating their promising antibacterial characteristics. The mechanism of antibacterial activity is investigated, and the results indicate that Spd-CQDs cause significant damage to the bacterial membrane. In vitro cytotoxicity and hemolysis analyses reveal the high biocompatibility of Spd-CQDs. To demonstrate its practical application, in vitro MRSA-infected wound healing studies in rats have been conducted, which show faster healing, better epithelialization, and formation of collagen fibers when Spd-CQDs are used as a dressing material.

Hhip haploinsufficiency sensitizes mice to age-related emphysema.

Genetic variants in Hedgehog interacting protein (HHIP) have consistently been associated with the susceptibility to develop chronic obstructive pulmonary disease and pulmonary function levels, including the forced expiratory volume in 1 s (FEV1), in general population samples by genome-wide association studies. However, in vivo evidence connecting Hhip to age-related FEV1 decline and emphysema development is lacking. Herein, using Hhip heterozygous mice (Hhip(+/-)), we observed increased lung compliance and spontaneous emphysema in Hhip(+/-) mice starting at 10 mo of age. This increase was preceded by increases in oxidative stress levels in the lungs of Hhip(+/-) vs. Hhip(+/+) mice. To our knowledge, these results provide the first line of evidence that HHIP is involved in maintaining normal lung function and alveolar structures. Interestingly, antioxidant N-acetyl cysteine treatment in mice starting at age of 5 mo improved lung function and prevented emphysema development in Hhip(+/-) mice, suggesting that N-acetyl cysteine treatment limits the progression of age-related emphysema in Hhip(+/-) mice. Therefore, reduced lung function and age-related spontaneous emphysema development in Hhip(+/-) mice may be caused by increased oxidative stress levels in murine lungs as a result of haploinsufficiency of Hhip.

Enzyme-free surface plasmon resonance aptasensor for amplified detection of adenosine via target-triggering strand displacement cycle and Au nanoparticles.

Herein, we combine the advantage of aptamer technique with the amplifying effect of an enzyme-free signal-amplification and Au nanoparticles (NPs) to design a sensitive surface plasmon resonance (SPR) aptasensor for detecting small molecules. This detection system consists of aptamer, detection probe (c-DNA1) partially hybridizing to the aptamer strand, Au NPs-linked hairpin DNA (Au-H-DNA1), and thiolated hairpin DNA (H-DNA2) previously immobilized on SPR gold chip. In the absence of target, the H-DNA1 possessing hairpin structure cannot hybridize with H-DNA2 and thereby Au NPs will not be captured on the SPR gold chip surface. Upon addition of target, the detection probe c-DNA1 is forced to dissociate from the c-DNA1/aptamer duplex by the specific recognition of the target to its aptamer. The released c-DNA1 hybridizes with Au-H-DNA1 and opens the hairpin structure, which accelerate the hybridization between Au-H-DNA1 and H-DNA2, leading to the displacement of the c-DNA1 through a branch migration process. The released c-DNA1 then hybridizes with another Au-H-DNA1 probe, and the cycle starts anew, resulting in the continuous immobilization of Au-H-DNA1 probes on the SPR chip, generating a significant change of SPR signal due to the electronic coupling interaction between the localized surface plasma of the Au NPs and the surface plasma wave. With the use of adenosine as a proof-of-principle analyte, this sensing platform can detect adenosine specifically with a detection limit as low as 0.21 pM, providing a simple, sensitive and selective protocol for small target molecules detection.

Identification of adenine modulating AMPK activation in NIH/3T3 cells by proteomic approach.

AMP-activated protein kinase (AMPK) is a metabolic master switch maintaining the energy homeostasis in cells and thought to modulate cellular response to stresses. Adenine as well as a pharmacological AMPK activator, 5-aminoimidazole-4-carboxamide ribonucleoside (AICAR), induced the phosphorylation of AMPK and acetyl-CoA carboxylase in NIH/3T3 cells. Administration of adenine or AICAR increased the expression and translocation of glucose transporter 4, enhanced the cellular glucose uptake, and elevated the intracellular ATP level. To better understand the proteomic changes in response to exogenous adenine treatment, we performed two-dimensional difference gel electrophoresis (2DE-DIGE) and grouped protein spots with similar intensities prior to MS analysis. These process allowed us to exclude these constant expressed proteins, reduce the coverage from abundant signals and increase the identification of middle/lower expressed proteins. Bioinformatics analysis on the proteomic alterations suggested that both of adenine and AICAR could induce up-regulation of a panel of proteins associated with glucose metabolism. We also found that adenine upregulated expression of the glycolytic enzyme, hexokinase 2, indicating a link between adenine and AMPK-mediated glycolysis. Taken together, by demonstrating the adenine-mediated proteome changes in NIH/3T3 cells, our study provides useful information for the characteristics of adenine-induced AMPK activation and development of efficient AMPK activator. BIOLOGICAL SIGNIFICANCE: AMPK is a fuel sensing enzyme that responds to a central role of energy homeostasis and contributes to the acceleration of insulin signaling. Recently, we have shown that exogenous adenine exerted anti-inflammatory effects through activation of AMPK, suggesting the treatment is a potent therapeutic strategy against hyperglycemia. Adenine had similar effects with 5-amino-4-imidazole-carboxamide riboside (AICAR, an AMPK activator) in modulating glucose uptake via AMPK-mediated signaling. In this study, we performed a 2DE-DIGE/MS-based approach to investigate the mechanism of exogenous adenine in NIH/3T3 cells. Our results provide evidence of a novel role for adenine in AMPK-mediated signaling and glucose metabolism and suggest potential therapeutic perspectives in insulin resistance and metabolic dysfunctions.

Target-triggering multiple-cycle amplification strategy for ultrasensitive detection of adenosine based on surface plasma resonance techniques.

An ultrasensitive protocol for surface plasma resonance (SPR) detection of adenosine is designed with the aptamer-based target-triggering cascade multiple cycle amplification, and streptavidin-coated Au-NPs (Au NPs-SA) enhancement to enhance the SPR signals. The cascade amplification process consists of the aptamer-based target-triggering nicking enzyme signaling amplification (T-NESA), the nicking enzyme signaling amplification (NESA) and the hybridization chain reaction (HCR), the entire circle amplification process is triggered by the target recognition of adenosine. Upon recognition of the aptamer to target adenosine, DNA s1 is released from the aptamer and then hybridizes with hairpin DNA (HP1). The DNA s1 can be dissociated from HP1 under the reaction of nicking endonuclease to initiate the next hybridization and cleavage process. Moreover, the products of the upstream cycle (T-NESA) (DNA s2 and s3) could act as the "DNA trigger" of the downstream cycle (NESA and HCR) to generate further signal amplification, resulting in the immobilization of abundant Au NPs-SA on the gold substrate, and thus significant SPR enhancement is achieved due to the electronic coupling interaction between the localized surface plasma of Au NPs and the surface plasma wave. This detection method exhibits excellent specificity and sensitivity toward adenosine with a detection limit of 4 fM. The high sensitivity and specificity make this method a great potential for detecting biomolecules with trace amounts in bioanalysis and clinical biomedicine.

Amelioration of LPS-induced inflammation response in microglia by AMPK activation.

Adenosine 5'-monophosphate-activated protein kinase (AMPK) is a key regulator of cellular energy homeostasis via modulating metabolism of glucose, lipid, and protein. In addition to energy modulation, AMPK has been demonstrated to associate with several important cellular events including inflammation. The results showed that ENERGI-F704 identified from bamboo shoot extract was nontoxic in concentrations up to 80 µM and dose-dependently induced phosphorylation of AMPK (Thr-172) in microglia BV2 cells. Our findings also showed that the treatment of BV2 with ENERGI-F704 ameliorated the LPS-induced elevation of IL-6 and TNF-α production. In addition, ENERGI-F704 reduced increased production of nitric oxide (NO) and prostaglandin E2 (PGE2) via downregulating the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase 2 (COX-2), respectively. Moreover, ENERGI-F704 decreased activated nuclear translocation and protein level of NF-κB. Inhibition of AMPK with compound C restored decreased NF-κB translocation by ENERGI-F704. In conclusion, ENERGI-F704 exerts inhibitory activity on LPS-induced inflammation through manipulating AMPK signaling and exhibits a potential therapeutic agent for neuroinflammatory disease.

Surface plasmon resonance sensor based on magnetic molecularly imprinted polymers amplification for pesticide recognition.

We reported here a method to enhance detection sensitivity in surface plasmon resonance (SPR) spectroscopy integrated with a surface molecular imprinting recognition system and employing magnetic molecular imprinting polymer nanoparticles for amplifying SPR response. The proposed magnetic molecular imprinting polymer was designed by self-polymerization of dopamine on the Fe3O4 NPs surface in weak base aqueous solution in the presence of template chlorpyrifos (CPF). The imprinted Fe3O4@polydopamine nanoparticles (Fe3O4@PDA NPs) were characterized by Fourier transform infrared spectroscopy, UV-vis absorption spectroscopy, and transmission electron microscopy. The biosensor showed a good linear relationship between the SPR angle shift and the chlorpyrifos concentration over a range from 0.001 to 10 µM with a detection limit of 0.76 nM. A significant increase in sensitivity was therefore afforded through the use of imprinted Fe3O4@PDA NPs as an amplifier, and meanwhile, the imprinted Fe3O4@PDA NPs had an excellent recognition capacity to chlorpyrifos over other pesticides. The excellent sensitivity and selectivity and high stability of the designed biosensor make this magnetic imprinted Fe3O4@PDA NP an attractive recognition element for various SPR sensors for detecting pesticide residuals and other environmentally deleterious chemicals.