The use of colloidal nanoparticles suffers from the drawbacks of potential color interference and substrate-induced aggregation. To overcome the limitations, a catalyst was developed by crosslinking ...Cu-doped carbon dots (Cu-CDs) with chitosan. Cu-CDs with high peroxidase activity were prepared by using a rapid microwave-assisted method. The Cu-CDs containing 6.88% of Cu had an average particle size of 2.25 nm and exhibited 9% of fluorescence quantum yield. The nanozyme/film composite was prepared by crosslinking between the amino groups of Cu-CDs and those of chitosan via a glutaraldehyde linker. A H
2
O
2
-mediated tetramethylbenzidine (TMB) oxidation reaction was use to evaluate the peroxidase activity of the film. Based on the TMB color changes, colorimetric assays were developed for the detection of H
2
O
2
and glucose at an absorption wavelength 652 nm. Under the optimal conditions, the linear ranges for H
2
O
2
and glucose were 0.625–40 µM and 1.9–125 µM, respectively, and the detection limits were 0.12 µM and 0.69 µM, respectively. The colorimetric assay was also applied to analyze diluted human serum samples spiked with glucose. Furthermore, this biodegradable, non-toxic, and easy-to-handle nanozyme composite could be stored for over 4 weeks without a significant decrease in activity.
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Boron and nitrogen co-doped carbon dots (B, N-CDs) were fabricated through a simple, one-step hydrothermal reaction of citric acid, boric acid, and tris base. The obtained B, N-CDs exhibit ...excitation-dependent fluorescence, high quantum yield (QY), biocompatibility, photostability, and aqueous solubility. The QY was substantially increased to 57% by doping boron atoms. Furthermore, the fluorescence intensity of B, N-CDs was temperature-dependent and decreased linearly from 283 to 333 K. The prepared B, N-CDs were used as a fluorescence probe for the detection of
-nitrophenol (p-NP) and Fe (III) ions with low detection limits of 0.17
M and 0.30
M, respectively. Moreover, the presence of p-NP could be further confirmed by a colorimetric assay. The fluorescent probe has been applied to determine p-NP and Fe (III) in a spiked serum sample and spiked water samples (lake and tap water). Moreover, the as-prepared B, N-CDs were of low toxicity and capable of bioimaging.
A nucleic acid aptamer that specifically recognizes methicillin-resistant Staphylococcus aureus (MRSA) has been immobilized on magnetic nanoparticles to capture the target bacteria prior to mass ...spectrometry analysis. After the MRSA species were captured, they were further eluted from the nanoparticles and identified using matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS). The combination of aptamer-based capture/enrichment and MS analysis of microorganisms took advantage of the selectivity of both techniques and should enhance the accuracy of MRSA identification. The capture and elution efficiencies for MRSA were optimized by examining factors such as incubation time, temperature, and elution solvents. The aptamer-modified magnetic nanoparticles showed a capture rate of more than 90% under the optimized condition, whereas the capture rates were less than 11% for non-target bacteria. The as-prepared nanoparticles exhibited only a 5% decrease in the capture rate and a 9% decrease in the elution rate after 10 successive cycles of utilization. Most importantly, the aptamer-modified nanoparticles revealed an excellent selectivity towards MRSA in bacterial mixtures. The capture of MRSA at a concentration of 102 CFU/mL remained at a good percentage of 82% even when the other two species were at 104 times higher concentration (106 CFU/mL). Further, the eluted MRSA bacteria were successfully identified using MALDI mass spectrometry.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Sample preparation methods used for genetically modified organisms (GMOs) analysis are often time consuming, require extensive manual manipulation, and result in limited amounts of purified protein, ...which may complicate the detection of low‐abundance GM protein. A robust sample pretreatment method prior to mass spectrometry (MS) detection of the transgenic protein (5‐enolpyruvylshikimate‐3‐phosphate synthase CP4 EPSPS) present in Roundup Ready soya is investigated. Liquid chromatography‐multiple reaction monitoring tandem MS (nano LC‐MS/MS‐MRM) was used for the detection and quantification of CP4 EPSPS. Gold nanoparticles (AuNPs) and concanavalin A (Con A)‐immobilized Sepharose 4B were used as selective probes for the separation of the major storage proteins in soybeans. AuNPs that enable the capture of cysteine‐containing proteins were used to reduce the complexity of the crude extract of GM soya. Con A‐sepharose was used for the affinity capture of β‐conglycinin and other glycoproteins of soya prior to enzymatic digestion. The methods enabled the detection of unique peptides of CP4 EPSPS at a level as low as 0.5% of GM soya in MRM mode. Stable‐isotope dimethyl labeling was further applied to the quantification of GM soya. Both probes exhibited high selectivity and efficiency for the affinity capture of storage proteins, leading to the quantitative detection at 0.5% GM soya, which is a level below the current European Union's threshold for food labeling. The square correlation coefficients were greater than 0.99. The approach for sample preparation is very simple without the need for time‐consuming protein prefractionation or separation procedures and thus presents a significant improvement over existing methods for the analysis of the GM soya protein.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
We present a sensitive and rapid screening method for the determination of β‐lactamase activity of antibiotic‐resistant bacteria, by designing a pH‐sensitive fluorescent dye‐doped mesoporous silica ...nanoparticle encapsulated with penicillin G as a substrate. When penicillin G was hydrolysed by β‐lactamase and converted into penicilloic acid, the acidic environment resulted in fluorescence quenching of the dye. The dye‐doped mesoporous nanoparticles not only enhanced the β‐lactamase‐catalyzed reaction rate but also stablized the substrate, penicillin G, which degrades into penicilloic acid in a water solution without β‐lactamase. Twentyfive clinical bacterial samples were tested and the antibiotic resistant and susceptible strains were identified. The proposed method may detect the presence of β ‐lactamases of clinically relevant samples in less than 1 hour. Moreover, the detection limit of β‐lactamase activity was as low as 7.8×10−4 U/mL, which was determined within two hours.
A pH‐sensitive fluorescent dye‐doped mesoporous silica nanoparticle encapsulated with penicillin G as a substrate was used for a screening assay to determine the β‐lactamase activity of antibiotic‐resistant bacteria. Twentyfive clinical bacterial samples were tested and the antibiotic resistant and susceptible strains were successfully identified.
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FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
Oxidative stress resulting from reactive oxygen species (ROS) is known to play a key role in numerous neurological disorders, including neuropathic pain. Morphine is one of the commonly used opioids ...for pain management. However, long-term administration of morphine results in morphine antinociceptive tolerance (MAT) through elevation of ROS and suppression of natural antioxidant defense mechanisms. Recently, mesoporous polydopamine (MPDA) nanoparticles (NPS) have been known to possess strong antioxidant properties. We speculated that morphine delivery through an antioxidant nanocarrier might be a reasonable strategy to alleviate MAT. MPDAs showed a high drug loading efficiency of ∼50%, which was much higher than conventional NPS. Spectral and in vitro studies suggest a superior ROS scavenging ability of NPS. Results from a rat neuropathic pain model demonstrate that MPDA-loaded morphine (MPDA@Mor) is efficient in minimizing MAT with prolonged analgesic effect and suppression of pro-inflammatory cytokines. Additionally, serum levels of liver enzymes and levels of endogenous antioxidants were measured in the liver. Treatment with free morphine resulted in elevated levels of liver enzymes and significantly lowered the activities of endogenous antioxidant enzymes in comparison with the control and MPDA@Mor-treated group. Histopathological examination of the liver revealed that MPDA@Mor can significantly reduce the hepatotoxic effects of morphine. Taken together, our current work will provide an important insight into the development of safe and effective nano-antioxidant platforms for neuropathic pain management.
Ensuring food safety requires a rapid and reliable method for detecting food-borne pathogens. Mass spectrometry has been demonstrated as a powerful tool to classify pure bacterial species. However, ...matrix interference from food backgrounds may lead to false results because of the suppression of microbial signals. It is useful to develop a method for bacterial enrichment and marker identification in food samples. Magnetic zirconia nanoparticles were used to concentrate spiked microorganisms from apple juice/lettuce under specific conditions (pH 4.5). Bacterial identification was achieved using nanoLC–MS. Selected reaction monitoring of bacteria-related peptides was applied for the first time to identify bacteria including Staphylococcus aureus and Escherichia coli. This study presents an accurate means for bacterial identification in food matrixes using MS. The analysis time is less than 90 min and the minimum concentration of E. coli detected was 5 × 103 CFU/mL. The interaction between bacteria and the magnetic nanoparticles was electrostatic and nonspecific, in contrast to immunoassays which require specific antibodies. The targeted peptide analysis focuses on the bacterial markers, thus significantly simplifying the analysis and leading to an accurate identification of bacteria.
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•Selected reaction monitoring of bacteria-related peptides was applied to identify bacteria.•Proteotypic peptides were analyzed by nanoLC–ESI MS and database searching.•Magnetic zirconia particles efficiently concentrate the bacterial cells in food matrixes.
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DOBA, GEOZS, IJS, IMTLJ, IZUM, KILJ, KISLJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SIK, UILJ, UKNU, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
With the aim of obtaining novel biologically active compounds, we have synthesized a series of mono, bis-2-
o-arylideneaminophenylbenzimidazoles and a second series of corresponding mono, ...bis-6-arylbenzimidazo1,2-
cquinazolines respectively. The target benzimidazo1,2-
cquinazoline compounds were obtained by the condensation of 2-(
o-aminophenyl)benzimidazole with mono and di carbonyl compounds, followed by oxidative cyclisation of the resulting mono and bis-2-
o-arylideneaminophenylbenzimidazoles.All the products were characterized via IR,
1H NMR,
13C NMR, MS and elemental analysis. The antimicrobial activities of all quinazolines against various bacteria and fungi were evaluated. Among the compounds tested
IVd,
IVe exhibited good antibacterial and antifungal activities while
IIIb,
IIIc also showed notable antimicrobial activity with reference to standard drugs Ampicillin and Ketoconazole respectively.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
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