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Plasmonic Colloidosomes Coupled MALDI-TOF MS for Bacterial Heteroresistance Study at Single-Cell Level
摘要： Antimicrobial resistance (AMR) is a long-term public health challenge worldwide, and it is increasingly recognized to be a heteroresistance phenomenon in an isogenic bacterial population. When the minority population of resistant bacteria with strong AMR is not handled in time, such sub-population can be enriched leading to the further development of bacterial AMR. However, conventional AMR studies based on ensemble-averaged data from large population fail to characterize the bacterial heterogeneity. In this work, we develop a method using plasmonic colloidosomes and matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry (MS) to study single bacterial cell AMR. The plasmonic colloidosomes act simultaneously as bacteria containers and sample spots for MALDI-TOF MS detection. Cells of β-lactamases producing Escherichia coli (E. coli) are trapped in colloidosome containers (~200 μm in diameter) in the presence of antibiotic drug ampicillin (AMP). Benefiting from the fast reaction kinetics in microcompartments, hydrolysis product of AMP by bacteria can be detected by MALDI-TOF MS within 40 min. The colloidosomes as MALDI sample spots also benefit sensitive detection and accurate quantification of AMP and its hydrolysis product. It was found that even an isogenic population could consist of a mixture of bacteria that have different resistance degrees to antibiotics. Taken the β-lactamases producing E. coli as an example, 20% of the bacterial individuals have relatively strong activity in hydrolyzing AMP. It is expected that the colloidosome-based platform would reveal a prospective application in full characterization of single bacterial cell AMR.
关键词： MALDI-TOF MS,Antimicrobial resistance,Single-cell level,Plasmonic colloidosomes,Bacterial heteroresistance
更新于2025-09-23 15:21:01
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Ultra-Stable Plasmonic Colloidal Aggregates for Accurate and Reproducible Quantitative SE(R)RS in Protein-Rich Biomedia
摘要： Au/Ag colloids aggregated with simple salts are amongst the most commonly used substrates in surface-enhanced (resonance) Raman spectroscopy (SE(R)RS). However, salt-induced aggregation is a dynamic process, which means that SE(R)RS enhancements vary with time and that measurements therefore need to be taken at a fixed time point, normally within a short time-window of a few minutes. Here, we present an emulsion templated method which allows formation of densely-packed quasi-spherical Au/Ag colloidal aggregates. Since the particles in the product aggregates retain their weakly adsorbed charged ligands and the ionic strength remains low these charged aggregates resist further aggregation while still providing intense SE(R)RS enhancement which remains stable for days. This eliminates a major source of irreproducibility in conventional colloidal SE(R)RS measurements and paves the way for SE(R)RS analysis in complex systems, such as protein-rich bio-solutions where conventional aggregated colloids fail.
关键词： self-assembly,interfaces,colloidosomes,SE(R)RS,aggregates
更新于2025-09-19 17:13:59
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Ultra‐Stable Plasmonic Colloidal Aggregates for Accurate and Reproducible Quantitative SE(R)RS in Protein‐Rich Biomedia
摘要： Au/Ag colloids aggregated with simple salts are amongst the most commonly used substrates in surface-enhanced (resonance) Raman spectroscopy (SE(R)RS). However, salt-induced aggregation is a dynamic process, which means that SE(R)RS enhancements vary with time and that measurements therefore need to be taken at a fixed time point, normally within a short time-window of a few minutes. Here, we present an emulsion templated method which allows formation of densely-packed quasi-spherical Au/Ag colloidal aggregates. Since the particles in the product aggregates retain their weakly adsorbed charged ligands and the ionic strength remains low these charged aggregates resist further aggregation while still providing intense SE(R)RS enhancement which remains stable for days. This eliminates a major source of irreproducibility in conventional colloidal SE(R)RS measurements and paves the way for SE(R)RS analysis in complex systems, such as protein-rich bio-solutions where conventional aggregated colloids fail.
关键词： self-assembly,colloidosomes,SE(R)RS,interfaces,aggregates
更新于2025-09-11 14:15:04
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Plasmonic Colloidosome-Based Multifunctional Platform for Bacterial Identification and Antimicrobial Resistance Detection
摘要： Antimicrobial resistance (AMR) is an urgent threat to public health. Rapid bacterial identification and AMR tests are important to promote personalized treatment of patients and to limit the spread of AMR. Herein, we explore the utility of plasmonic colloidosomes in bacterial analysis based on mass spectrometry (MS) and Raman scattering. It is found that colloidosomes can provide a rigid micron-size platform for bacterial culture and analysis. Coupled with matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) MS, this platform enables bacterial identification at the species level with cell counts as low as 50, > 100 times more sensitive than the standard method of MALDI-TOF MS based bacterial identification. Coupled with Raman scattering, it can distinguish single bacterial cells at the strain level and recognize AMR at the single-cell level. These reveal the broad potential of the platform for flexible and versatile bacterial detection and typing.
关键词： Plasmonic colloidosomes,MALDI-TOF MS,Raman scattering,antimicrobial resistance detection,bacterial identification
更新于2025-09-11 14:15:04
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Colloidal Capsules Assembled from Gold Nanoparticles Using Small-Molecule Hydrophobic Cross-linkers
摘要： Colloidal capsules (or colloidosomes) have been studied for various applications such as therapeutic agent encapsulation, photothermal therapy, imaging, and energy storage. Emulsion-based synthesis is the most common approach to preparing colloidal capsules as it is relatively straightforward and scalable. However, while the initial formation requires only introducing the colloidal subunits into an emulsion and letting them assemble at the interface, a second step is required in order to prepare stable, covalently linked colloidal capsules and preparing sub-micron colloidal capsules is quite challenging. Here we describe a simple and quick one-step method to synthesize covalently linked, stable nanoscale colloidal capsules consisting of gold nanoparticles (AuNP) and thiol-containing crosslinkers. Gold nanoparticle capsules (AuNCs) were formed by coating emulsion droplets containing thiol-containing crosslinkers with citrate-stabilized AuNPs. The physicochemical properties of the colloidal capsules can be tailored by changing the building blocks. In order to demonstrate this, colloidal capsules were assembled from AuNPs ranging from 5 nm to 20 nm in size. The use of the larger 20 nm starting particles resulted in AuNCs with a sufficiently pronounced red shift for λmax to be suitable for biological photothermal applications, where use of a NIR laser is strongly preferred. The AuNCs were found to be biocompatible and stable in cell culture condition and to provide moderate heating. This demonstrates the modularity of the synthesis and the potential advantages of a one-step synthesis to prepare nanoscale gold colloidal capsules.
关键词： Colloidal Capsules,photothermal,Colloidosomes,Gold nanoparticle capsules
更新于2025-09-11 14:15:04