SENSORS AND ACTUATORS B-CHEMICAL
·
2020
·
IF 7.1
Wenyao Chen,Shan Shan,Juan Peng,Daofeng Liu,Jun Xia,Bing Shao,Weihua Lai
The traditional lateral flow immunoassay (LFI) for detecting foodborne pathogens suffers from low sensitivity and hook effect that led false–negative result. Here, we established a novel LFI integrated with a cascade signal transduction system for the sensitive and hook effect–free detection of Escherichia coli O157:H7 ( E. coli O157:H7). First, E. coli O157:H7 was captured by immunomagnetic nanoparticles (IMNPs) and monoclonal antibody–β–lactamase–gold nanoparticles (ILAuNPs) forming sandwich complexes. Second, penicillin solution was added and hydrolyzed by β–lactamase on the sandwich complexes. Last, the penicillin hydrolysate was transferred to an ultrasensitive penicillin immunochromatographic test strip (PIST). With the high β–lactamase activity of ILAuNPs (0.1 μL of ILAuNPs hydrolyzing 20 ng/mL of penicillin) and ultrasensitive PIST (cutoff value achieving 2 ng/mL), the detection sensitivity of this method was 1.37 × 10 2 CFU/mL for E. coli O157:H7, which prevailed 1000 times over that of the traditional LFI. This work also efficiently solved hook effect when the E. coli O157:H7 concentration was over 10 7 CFU/mL. Thus, the detection range of the novel method was 10 2 –10 8 CFU/mL, thereby expanding by four orders of magnitude than that of the traditional LFI (10 5 –10 7 CFU/mL).
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高影响因子
NEW JOURNAL OF CHEMISTRY
·
2016
·Vol. 40
·期 3
·1982-1987
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IF 3.277
Chen Chen,Jun Lv,Wanyi Chen,Yang Xiang,Juan Zhang
A colorimetric method is developed for the determination of the activity of β-lactamase (β-Lac) and the screening of its inhibitors based on cysteine-induced gold nanoparticle (AuNP) aggregation. The widely used penicillin is served as a β-Lac substrate, and the strong reduction capability of its corresponding product, which can react with Cu(II) to form Cu(I) conjugates, is utilized in the method. The double catalyzed signal amplification is accomplished via the addition of both β-Lac and Cu(II) which can catalyze the oxidization of cysteine into cystine. The activity of β-Lac is determined at levels as low as 2.36 U mL−1. The inhibitory effects of clavulanic acid and sulbactam are tested and give 0.92 and 0.06 μM, respectively. The assay is simple, rapid, easy-operated, and selective, and the proposed method has a great potential not only for the detection of β-Lac activity but also for the screening of the inhibitors.
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高影响因子
ANALYTICAL CHEMISTRY
·
2014
·
IF 5.825
Lihong Li,Zhao Li,Wen Shi,Xiaohua Li,Huimin Ma
A highly sensitive and selective near-infrared (NIR) fluorescent probe, (E)-2-(2-(6-((2-carboxy-8-oxo-7-(2-phenylacetamido)-5-thia-1-azabicyclo[4.2.0]oct-2-en-3-yl)methoxy)-2,3-dihydro-1H-xanthen-4-yl)vinyl)-3,3-dimethyl-1-propyl-3H-indol-1-ium (1), is developed for the determination of β-lactamase. The probe is designed and synthesized by incorporating the specific substrate (cephalosporin) of β-lactamase into a stable hemicyanine skeleton. The fluorescence of 1 itself is very weak due to the alkylation of the hydroxyl group of the hemicyanine fluorophore; however, β-lactamase can selectively react with its substrate (β-lactam ring) in the probe, thereby causing a spontaneous fragmentation. This action leads to the release of the fluorophore and a large fluorescence enhancement at 707 nm (λex = 680 nm). Under the optimized conditions, the fluorescence response of probe 1 is directly proportional to the concentration of β-lactamase in the range of 0.05–2 nM, with a detection limit of 0.02 nM. The validity of the probe has been confirmed by determining β-lactamase in human urine samples in comparison with that determined by iodimetry. Moreover, by taking advantage of its high sensitivity and NIR emission feature, the probe has also been utilized to image β-lactamase in three types of Staphylococcus aureus, including methicillin-resistant S. aureus ATCC BAA44, penicillin-resistant strain ATCC 11632, and penicillin-susceptible strain ATCC 29213, which clearly reveals the significantly different expression levels of β-lactamase in these S. aureus.
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PubMed
高影响因子
JOURNAL OF DAIRY SCIENCE
·
2016
·
IF 2.408
Shan Shan,Daofeng Liu,Qi Guo,Songsong Wu,Rui Chen,Kai Luo,Liming Hu,Yonghua Xiong,Weihua Lai
In this study, cascade signal amplification in ELISA involving double-antibody sandwich ELISA and indirectly competitive ELISA was established to sensitively detect Escherichia coli O157:H7. In the double-antibody sandwich ELISA, a complex was formed comprising anti- E. coli O157:H7 polyclonal antibody, E. coli O157:H7, biotinylated anti- E. coli O157:H7 monoclonal antibody, streptavidin, and biotinylated β-lactamase. Penicillin solution was then added into the ELISA well and hydrolyzed by β-lactamase. Afterward, the penicillin solution was transferred to indirectly competitive ELISA. The concentration of penicillin can be sensitively detected in indirectly competitive ELISA. In the cascade signal amplification system, increasing the amount of added E. coli O157:H7 resulted in more β-lactamase and less penicillin. The detection sensitivity of E. coli O157:H7, which was 20 cfu/mL with the cascade signal amplification in ELISA, was 1,000-fold higher than that of traditional ELISA. Furthermore, the novel method can be used to detect E. coli O157:H7 in milk (2 cfu/g). Therefore, this new signaling strategy will facilitate analyses of highly sensitive foodborne pathogens.
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高影响因子
CARBOHYDRATE POLYMERS
·
2024
·
IF 10.7
Junfeng Liu,Liying Zhang,Haodi Ma,Haoyang Sun,Shu-ai Ge,Jieyi Liu,Shengdi Fan,Chunshan Quan
The limited membrane permeability and bacterial resistance pose significant challenges in the management of intracellular drug-resistant bacterial infections. To overcome this issue, we developed a bacterial-targeted drug delivery system based on quaternary ammonium chitosan-modified mesoporous silica nanoparticles (MSN-NH 2 -CFP@HACC) for the treatment of intracellular Methicillin-resistant Staphylococcus aureus (MRSA) infections. This system utilizes amino-functionalized mesoporous silica nanoparticles to efficiently load cefoperazone (CFP), and the nanoparticles' surface is coated with 2-hydroxypropyltrimethyl ammonium chloride chitosan (HACC) to target bacteria and enhance macrophage uptake. The findings indicate that MSN-NH 2 -CFP@HACC nanoparticles are efficiently internalized by macrophages, demonstrate accelerated drug release in acidic environments, and exhibit enhanced antibacterial properties, effectively suppressing the proliferation and intracellular escape of MRSA. Moreover, HACC enhances the bacterial capture ability of the nanoparticles and reduces resistance by disrupting bacterial membrane structures and inhibiting bacterial β-lactamase activity. In a murine model of MRSA bacteremia, MSN-NH 2 -CFP@HACC exhibited remarkable antibacterial efficacy and significantly attenuated severe inflammatory responses. In conclusion, MSN-NH 2 -CFP@HACC represent a promising antibiotic delivery system with exceptional antibacterial efficacy and favorable biocompatibility, thus presenting a novel strategy for addressing intracellular drug-resistant bacterial infections and demonstrating significant potential for clinical application.
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