Human Serum Albumin Stabilized Gold Nanoclusters as Selective Luminescent Probes for Staphylococcus aureus and Methicillin-Resistant Staphylococcus aureus (original) (raw)
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Staphylococcus aureus (S. aureus) is one of the most ubiquitous pathogens in public healthcare worldwide. It holds great insterest in establishing robust analytical method for S. aureus. Herein, we report a S. aureus-specific recognition element, isolated from phage monoclone GQTTLTTS, which was selected from f8/8 landscape phage library against S. aureus in a high-throughput way. By functionalizing cysteamine (CS)-stabilized gold nanoparticles (CS-AuNPs) with S. aureus-specific pVIII fusion protein (fusion-pVIII), a bifunctional nanoprobe (CS-AuNPs@fusion-pVIII) for S. aureus was developed. In this strategy, the CS-AuNPs@fusion-pVIII could be induced to aggregate quickly in the presence of target S. aureus, resulting in a rapid colorimetric response of gold nanoparticles. More importantly, the as-designed probe exhibited excellent selectivity over other bacteria. Thus, the CS-AuNPs@fusion-pVIII could be used as the indicator of target S. aureus. This assay can detect as low as 19 CFU mL À 1 S. aureus within 30 min. Further, this approach can be applicable to detect S. aureus in real water samples. Due to its sensitivity, specificity and rapidness, this proposed method is promising for on-site testing of S. aureus without using any costly instruments.
Analytical chemistry, 2015
Staphylococcus aureus is one of the common pathogenic bacteria responsible for bacterial infectious diseases and food poisoning. This study presents an analytical method based on the affinity nanoprobe-based mass spectrometry that enables detection of S. aureus in aqueous samples. A peptide aptamer DVFLGDVFLGDEC (DD) that can recognize S. aureus and methicillin-resistant S. aureus (MRSA) was used as the reducing agent and protective group to generate DD-immobilized gold nanoparticles (AuNPs@DD) from one-pot reactions. The thiol group from cysteine in the peptide aptamer, i.e., DD, can interact with gold ions to generate DD-immobilized AuNPs in an alkaline solution. The generated AuNPs@DD has an absorption maximum at ∼518 nm. The average particle size is 7.6 ± 1.2 nm. Furthermore, the generated AuNPs@DD can selectively bind with S. aureus and MRSA. The conjugates of the target bacteria with AuNPs were directly analyzed by surface-assisted laser desorption/ionization mass spectrometry...
Molecular and cellular probes, 2018
Staphylococcus aureus is a gram-positive and opportunistic pathogen that is one of the most common causes of nosocomial infections; therefore, its rapid diagnosis is important and valuable. Today, the use of nanoparticles is expanding due to their unique properties. The purpose of the present study is the determination of S. aureus by a colorimetric method based on gold nanoparticles (AuNPs). Firstly, S. aureus was cultured on both LB media (broth and agar) and their chromosomal DNA was extracted. Afterwards, primers and biosensor were designed based on Protein A sequence data in the gene bank. PCR assay was performed under optimal conditions and the PCR product was electrophoresed on 2-percent agarose gel. The synthesized biosensors were conjugated with AuNPs and, eventually, a single-stranded genome was added to the conjugated AuNPs and hybridization was performed. The results were evaluated based on color change detected by the naked eye, optical spectrophotometry, and transient ...
Lysozyme-encapsulated gold nanocluster-based affinity mass spectrometry for pathogenic bacteria
Rapid Communications in Mass Spectrometry, 2013
RATIONALE: Bacterial infections can be difficult to treat and can lead to irreversible damage to patients if proper treatment is not provided in time. Additionally, the emerging threat from antibiotic-resistant bacterial strains makes medical treatment even more difficult. Thus, rapid identification of infected bacterial strains is essential to assist diagnostics and medical treatment. METHODS: Lysozymes are glycoside hydrolases that can bind with peptidoglycans on bacterial cell walls. In this work, we demonstrated that lysozyme-encapsulated gold nanoclusters (lysozyme-AuNCs) with red photoluminescence can be used as affinity probes to concentrate pathogenic bacteria. After bacteria had been probed by the lysozyme-AuNCs in a sample solution, the lysozyme-AuNC-bacteria conjugates were readily spun down at a low centrifugation speed. The red emission from the AuNCs on the conjugates could be visualized with the naked eye under illumination of ultraviolet light. The bacteria in the conjugates can be identified by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) combined with principal component analysis (PCA). RESULTS: We demonstrated that pathogenic bacteria including Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, pandrug-resistant Acinetobacter baumannii, Staphylococcus aureus, Enterococcus faecalis, and vancomycin-resistant Enterococcus faecalis (VRE) can be readily concentrated by the lysozyme-AuNCs and distinguished by the results combining MALDI-MS and PCA. Additionally, the possibility of using the current approach to differentiate E. faecalis from VRE was also demonstrated. The lowest detection concentration for E. coli using the current approach is~10 6 cells/mL. CONCLUSIONS: The results indicated that the lysozyme-AuNCs are effective affinity probes for Gram-positive and Gram-negative bacteria. By combining the results from MALDI-MS and PCA, different bacteria can be easily distinguished. The current approach can be potentially used to assist the identification of bacteria from biological fluids.
Photoluminescent Gold Nanoclusters as Sensing Probes for Uropathogenic Escherichia coli
PLoS ONE, 2013
Glycan-bound nanoprobes have been demonstrated as suitable sensing probes for bacteria containing glycan binding sites. In this study, we demonstrated a facile approach for generating glycan-bound gold nanoclusters (AuNCs). The generated AuNCs were used as sensing probes for corresponding target bacteria. Mannose-capped AuNCs (AuNCs@Mann) were generated and used as the model sensors for target bacteria. A one-step synthesis approach was employed to generate AuNCs@Mann. In this approach, an aqueous solution of tetrachloroauric acid and mannoside that functionized with a thiol group (Mann-SH) was stirred at room temperature for 48 h. The mannoside functions as reducing and capping agent. The size of the generated AuNCs@Mann is 1.9560.27 nm, whereas the AuNCs with red photoluminescence have a maximum emission wavelength of ,630 nm (l excitation = 375 nm). The synthesis of the AuNCs@Mann was accelerated by microwave heating, which enabled the synthesis of the AuNCs@Mann to complete within 1 h. The generated AuNCs@Mann are capable of selectively binding to the urinary tract infection isolate Escherichia coli J96 containing the mannose binding protein FimH expressed on the type 1 pili. On the basis of the naked eye observation, the limit of detection of the sensing approach is as low as ,2610 6 cells/mL.
Functional gold nanoclusters as antimicrobial agents for antibiotic-resistant bacteria
Nanomedicine, 2010
Aims: Our aim was to demonstrate that lysozyme-directed generation of gold nanoclusters (Au NCs) are potential antimicrobial agents for antibiotic-resistant bacteria and broad labeling agents for pathogenic bacteria. Materials & methods: Lysozyme is an enzyme that is capable of hydrolyzing the cell walls of bacteria. In this study, we demonstrated the generation of functional Au NCs by using lysozyme as the sequester and the reducing agent for Au precursors at 40°C. In addition, to shorten the reaction time, the reaction was conducted under microwave irradiation within a short period of time for the first time. Results: The bioactivity of the lysozyme on the Au NCs was retained. Therefore, the as-prepared lysozyme–Au NCs with desirable fluorescence feature were successfully employed to be broad-band labeling agents for pathogenic bacteria. Furthermore, we also demonstrated that the lysozyme–Au NCs can be used to effectively inhibit the cell growth of notorious antibiotic-resistant b...
ACS omega, 2018
Herein, we introduce a new facile method of luminescent gold nanocluster (Au NC) synthesis on the surface of bacteria for detection, counting, and strain differentiation. The limit of detection was 740 ± 14 colony-forming unit (CFU)/mL for the Gram-negative and was 634 ± 16 CFU/mL for the Gram-positive bacteria. Brief treatment with lysozyme could differentiate the Gram strains based on their luminescence intensities. The current method could also detect bacterial contaminants from water sources and kanamycin-resistant strains rapidly. This quick synthesis of Au NCs on a bacterial template attributes an easy and rapid method for enumeration and detection of bacterial contaminants and kanamycin-resistant strains.
Detection of pathogenic Staphylococcus aureus bacteria by gold based immunosensors
Mikrochimica Acta, 2008
We describe the elaboration of ultra-sensitive immunosensors, to detect the bacterial pathogen Staphylococcus aureus. We utilized commercially available polyclonal anti-S. aureus antibody as receptor. Immunosensors were elaborated by building a self-assembled monolayer (SAM) of thiolamine onto planar gold-coated sensor chips. Then, Protein A was covalently linked to the thiolated SAM using glutaraldehyde as cross-linking agent. After a blocking step by Bovine Serum Albumin (BSA), the antibody was immobilized by affinity to Protein A. This step-by-step construction was monitored by Polarization Modulation Reflection Absorption Infrared Spectroscopy (PM-RAIRS) and Quartz Crystal Microbalance with Dissipation (QCM-D). In a first stage, the parameters of immunosensor elaboration were optimized using a model rabbit IgG. The accessibility of receptors and the homogeneity of their distribution were checked by PM-RAIRS, QCM-D, and by immuno-gold scanning electron microscopy. Then, the specific rabbit anti-S. aureus antibody was immobilized and the resulting sensing layer was applied to the detection of the pathogen target. Independent detection of bacteria immobilized on the sensors by fluorescent imaging allowed validation of the specificity of recognition toward the pathogen as well as a quantitative response of the sensor. Using PM-RAIRS as transducing technique allowed us to enhance sensitivity and reach a very competitive detection level (105 CFU mL−1).
Binding of Escherichia coli to Functionalized Gold Nanoparticles
Plasmonics, 2012
The molecular basis of the diversity of fimbrial lectins dictates the extent of adhesion in different types of Escherichia coli strains to mammalian cells. The mechanism of receptor binding by E. coli in eukaryotic cells differs based on the adhesin domains, patterns in the macromolecular structure and the ligand-binding groove. Current sensor technologies utilize biosensors that are based on the carbohydrate moieties that are involved in pathogen adhesion to host cells. Nanoparticles have been extensively used as carriers for pathogen detection. Gold nanoparticles (Au NPs) of 200 nm size were functionalized with two distinct glycoconjugates mannose (Mn-Au NPs) and Neuαc(α2-3)-Gal-(β1-4)Glc-Paa (Sg-Au NPs) in order to investigate primary and fine sugar specificity of uropathogenic E. coli ORN178 and enterotoxigenic E. coli 13762, respectively. The UV-Vis measurement of pristine, 16mercaptohexadecanoic acid (MHDA)/2-(2-aminoethoxy) ethanol (AEE)/sugar functionalized Au NPs showed a surface plasmon resonance band for Au. Dynamic light scattering analysis showed that the mean averages of the MHDA/AEE/Mn-Au NP samples increased due to aggregation. The negative zeta potentials of the samples were indicative of aggregation. Fine sugar specificity was observed when Neuαc(α2-3)-Gal-(β1-4)Glc-Paa functionalized Au NPs (Sg-Au NPs) specifically showed binding with E. coli 13762 but not with E. coli ORN178. This specificity of E. coli strains to identify and bind to characteristic sugar moieties can be used in the development of biodiagnostic tools with Au NPs as carriers for diagnosis/treatment of human and veterinary diseases. In regards to the growing antibiotic resistance of microorganisms, gold nanoparticles can also be functionalized specifically to reverse adhesion of E. coli to host tissue and can be detected by their optical properties.
Bio-hybrid gold nanoparticles as SERS probe for rapid bacteria cell identification
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2019
This study reports the utilization of engineered molecular networks between bacteriophage (or phage) and gold nanoparticles (AuNPs) prepared ablating a high purity gold target in water by nanosecond laser source. Gold colloids are assembled with P9b phage clone, displaying the specific peptide (QRKLAAKLT), able to bind P. aeruginosa. The single components and assembled systems were characterized by spectroscopic and electronic techniques, such as the conventional optical absorption and micro-Raman spectroscopies as well as the Dynamic Light Scattering (DLS) and Scanning Transmission Electron Microscopy (STEM) techniques. The performance of the AuNPs-phage assembly as substrate for Surface-Enhanced Raman Spectroscopy (SERS) was tested against the detection of the characteristics Raman vibrational features of the Pseudomonas aeruginosa bacteria.