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A luminous off-on probe for the determination of 2,6-pyridinedicarboxylic acid as an anthrax biomarker based on water-soluble cadmium sulfide quantum dots
摘要： A fluorescence off-on sensing platform was developed based on thioglycolic acid-stabilized cadmium sulfide quantum dots (CdS QDs) as fluorescence probe for the sensitive and selective detection of 2,6-pyridinedicarboxylic acid (DPA) in spores. The fluorescence emission intensity of the quantum dots at 650 nm when excited at 460 nm was first quenched by mixing with europium ions (Eu3+) and then recovered after the addition of DPA. The interaction of DPA with Eu3+ relieved the quenching effect of Eu3+ toward CdS QDs. As the DPA concentration increases, the color of the probe changes from colorless to red. The method exhibits a wide linear range from 1 to 120 μM for DPA determination, with a detection limit of 0.2 μM. The CdS QDs based nanoprobe was successfully applied for sensitive determination of DPA released from bacteria spores. In this case, the detection limit is 3.5 × 104 CFU·mL?1.
关键词： Bacillus anthracis,CdS quantum dots,2, 6-Pyridinedicarboxylic acid,Bacteria spores,Fluorescence recovery
更新于2025-09-23 15:19:57
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Highly Sensitive Optical Biosensing of Staphylococcus aureus with an Antibody/Metal-Organic Framework Bioconjugate
摘要： In this research, a new luminescent bioprobe was developed for the detection of S. aureus based on bio-conjugation of an amine functionalized metal-organic framework (NH2-MIL-53(Fe)) with an anti-S. aureus antibody (Ab). The formation of the desired bioprobe (Ab/NH2-MIL-53), in its liquid phase, has been verified with several spectroscopic and structural characterizations. The bioprobe was incubated with varying concentrations of S. aureus bacteria. The resulting antibody conjugated bioprobe (Ab/NH2-MIL-53) maintained a strong inverse correlation in which decreases in fluorescence intensity were accompanied by increase in bacterial count. Thus, the potential of the herein developed probe has been successfully demonstrated for the detection of S. aureus with a low limit of detection (85 CFU/mL) over a wide concentration range (40 × 102 - 4 × 108 CFU/mL). It was further found to be reliable with regard to inter-/intra- precision assays and long-term stability. The feasibility of the method was further supported through the detection of S. aureus spiked in environmental samples (e.g., river water and cream pastry).
关键词： bacteria,real sample analysis,S. aureus,fluorescent sensor,Metal-organic framework
更新于2025-09-19 17:15:36
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Self-assembling nanoprobes that display two-dimensional fluorescent signals for identification of surfactants and bacteria
摘要： The imidazolium-pyrene self-assembling nanoprobes can rapidly discriminate four types of surfactants. The surfactants disassembled the probes to turn on significant fluorescence and transform between a pyrene monomer and an excimer, generating a two-dimensional analysis map. The probes were further used to identify different bacterial species.
关键词： fluorescence,surfactants,nanoprobes,self-assembly,bacteria
更新于2025-09-19 17:15:36
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Bioinspired magnetic nanoparticles as multimodal photoacoustic, photothermal and photomechanical contrast agents
摘要： Nanoparticles from magnetotactic bacteria have been used in conventional imaging, drug delivery, and magnetic manipulations. Here, we show that these natural nanoparticles and their bioinspired hybrids with near-infrared gold nanorods and folic acid can serve as molecular high-contrast photoacoustic probes for single-cell diagnostics and as photothermal agents for single-cell therapy using laser-induced vapor nanobubbles and magnetic field as significant signal and therapy amplifiers. These theranostics agents enable the detection and photomechanical killing of triple negative breast cancer cells that are resistant to conventional chemotherapy, with just one or a few low-energy laser pulses. In studies in vivo, we discovered that circulating tumor cells labeled with the nanohybrids generate transient ultrasharp photoacoustic resonances directly in the bloodstream as the basis for new super-resolution photoacoustic flow cytometry in vivo. These properties make natural and bioinspired magnetic nanoparticles promising biocompatible, multimodal, high-contrast, and clinically relevant cellular probes for many in vitro and in vivo biomedical applications.
关键词： theranostics,super-resolution,contrast agents,photomechanical,photoacoustic,magnetic nanoparticles,photothermal,circulating tumor cells,bioinspired,magnetotactic bacteria
更新于2025-09-19 17:15:36
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EXPRESS: Cyclic Changes in the Amide Bands Within <i>Escherichia coli</i> Biofilms Monitored Using Real-Time Infrared Attenuated Total Reflection Spectroscopy
摘要： Contrary to the planktonic state of bacteria, their biofilm form represents severe complications in areas such as human medicine or food industry due to the increasing resistance against harsh conditions and treatment. In the present study, infrared attenuated total reflection (IR-ATR) spectroscopy has been applied as an analytic tool studying Escherichia coli (E. coli) biofilm formation close to real time. We report on IR spectroscopic investigations on the biofilm formation via ATR waveguides probing the biofilm in the spectral window of 1800–900 cm?1 at dynamic flow conditions, which facilitated monitoring the growth dynamics during several days. Key IR bands are in the range 1700–1590 cm?1 (amide I), 1580–1490 cm?1 (amide II), and 1141–1006 cm?1 extracellular polymeric substances (EPS), which were evaluated as a function of time. Cyclic fluctuations of the amide I and amide II bands and a continuous increase of the EPS band were related to the starvation of bottom-layered bacteria caused by the nutrient gradient. Potential death of bacteria may then result in cannibalistic behavior known for E. coli colonies. Observing this behavior via IR spectroscopy allows revealing these cyclical changes in bottom-layered bacteria within the biofilm under continuous nutrient flow, in molecular detail, and during extended periods for the first time.
关键词： bacteria,starvation,Escherichia coli,EPS,IR-ATR spectroscopy,amide band,biofilm,infrared attenuated total reflectance
更新于2025-09-19 17:15:36
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Microbial Ecology on Solar Panels in Berkeley, CA, United States
摘要： Solar panels can be found practically all over the world and represent a standard surface that can be colonized by microbial communities that are resistant to harsh environmental conditions, including high irradiation, temperature fluctuations and desiccation. These properties make them not only ideal sources of stress-resistant bacteria, but also standard devices to study the microbial communities and their colonization process from different areas of Earth. We report here a comprehensive description of the microbial communities associated with solar panels in Berkeley, CA, United States. Cultivable bacteria were isolated to characterize their adhesive capabilities, and UV- and desiccation-resistance properties. Furthermore, a parallel culture-independent metagenomic and metabolomic approach has allowed us to gain insight on the taxonomic and functional nature of these communities. Metagenomic analysis was performed using the Illumina HiSeq2500 sequencing platform, revealing that bacterial population of the Berkeley solar panels is composed mainly of Actinobacteria, Bacteroidetes and Proteobacteria, as well as lower amounts of Deinococcus-Thermus and Firmicutes. Furthermore, a clear predominance of Hymenobacter sp. was also observed. A functional analysis revealed that pathways involved in the persistence of microbes on solar panels (i.e., stress response, capsule development, and metabolite repair) and genes assigned to carotenoid biosynthesis were common to all metagenomes. On the other hand, genes involved in photosynthetic pathways and general autotrophic subsystems were rare, suggesting that these pathways are not critical for persistence on solar panels. Metabolomics was performed using a liquid chromatography tandem mass spectrometry (LC-MS/MS) approach. When comparing the metabolome of the solar panels from Berkeley and from Valencia (Spain), a very similar composition in polar metabolites could be observed, although some metabolites appeared to be differentially represented (for example, trigonelline, pantolactone and 5-valerolactone were more abundant in the samples from Valencia than in the ones from Berkeley). Furthermore, triglyceride metabolites were highly abundant in all the solar panel samples, and both locations displayed similar profiles. The comparison of the taxonomic profile of the Californian solar panels with those previously described in Spain revealed striking similarities, highlighting the central role of both selective pressures and the ubiquity of microbial populations in the colonization and establishment of microbial communities.
关键词： microbiome,stress-resistant bacteria,solar panels,metabolomics,metagenomics
更新于2025-09-19 17:15:36
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Photo-inactivation and efflux pump inhibition of methicillin resistant Staphylococcus aureus using thiolated cobalt doped ZnO nanoparticles
摘要： Multidrug resistance (MDR) in bacteria is a major concern these days. One of the reasons is the mutation in efflux pump that prevents the retention of antibiotics and drugs in the bacterial cell. The current work is a step to overcome MDR in bacteria via inhibition of efflux pump and further photoinhibition by thiolated chitosan coated cobalt doped zinc oxide nanoparticles (Co-ZnO) in visible light. Co-ZnO were synthesized in a size range of 40–60 nm. Antibacterial activity of the Co-ZnO against methicillin resistant Staphylococcus aureus (MRSA) was found 100% at a concentration of 10 μg/ml upon activation in sunlight for 15 min. Interestingly, it was found that cobalt as a dopant was able to increase the photodynamic and photothermal activity of Co-ZnO, as in dark conditions, there was only 3–5% of inhibition at 10 μg/ml of nanoparticle concentration. Upon excitation in light, these nanoparticles were able to generate reactive oxygen species (ROS) with a quantum yield of 0.23 ± 0.034. The nanoparticles were also generating heat, Because of the magnetic nature, thus helping in more killing. Thiolated chitosan further helped in blocking the efflux pump of MRSA. The current nanoparticles were also found biocompatible on human red blood cells (LD50 = 214 μg/ml). These data suggest that the MRSA killing ability was facilitated through efflux inhibition and oxidative stress upon excitation in visible light hence, were in accordance with previous findings.
关键词： Multidrug resistant bacteria,Biocompatibility,ZnO nanoparticles,Photo-inactivation,ROS,MRSA
更新于2025-09-19 17:15:36
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Nanoplasmonic sensor for foodborne pathogens detection. Towards development of ISOa??SERSa??PCA methodology of taxonomic affiliation of Campylobacter spp
摘要： According to EU summary report on zoonoses, zoonotic agents and food-borne outbreaks in 2017, Campylobacter was the most commonly reported gastrointestinal bacterial pathogen in humans in the EU. Unfortunately, the standard methods for detection of thermotolerant Campylobacter spp. in foods are time-consuming. Additionally, the qualified staff is obligatory. For this reason, the new methods of pathogens detection are needed. The present work demonstrates that surface-enhanced Raman scattering (SERS) is a reliable and fast method for detection of Campylobacter spp. in food samples. The proposed method combines the SERS measurements performed on an Ag/Si substrate with two initial steps of the ISO standard procedure. Finally, the principal component analysis (PCA) allows for statistical classification of the studied bacteria. By applying the proposed ISO-SERS-PCA method in the case of Campylobacter bacteria the total detection time may be reduced from 7-8 days required by ISO method to 3-4 days in the case of SERS-based approach.
关键词： PCA,ISO,foodborne bacteria,surface-enhanced Raman spectroscopy,SERS,Campylobacter spp.
更新于2025-09-19 17:13:59
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[IEEE 2019 10th IEEE International Conference on Intelligent Data Acquisition and Advanced Computing Systems: Technology and Applications (IDAACS) - Metz, France (2019.9.18-2019.9.21)] 2019 10th IEEE International Conference on Intelligent Data Acquisition and Advanced Computing Systems: Technology and Applications (IDAACS) - Solar Cell Data Acquisition System
摘要： The development of two new types of high-density, electroless plated microelectrode arrays for CMOS-based high-sensitivity direct bacteria and HeLa cell counting are presented. For emerging high-sensitivity direct pathogen counting, two technical challenges must be addressed. One is the formation of a bacteria-sized microelectrode, and the other is the development of a high-sensitivity and high-speed amperometry circuit. The requirement for microelectrode formation is that the gold microelectrodes are required to be as small as the target cell. By improving a self-aligned electroless plating technique, the dimensions of the microelectrodes on a CMOS sensor chip in this work were successfully reduced to 1.2 μm × 2.05 μm. This is 1/20th of the smallest size reported in the literature. Since a bacteria-sized microelectrode has a severe limitation on the current flow, the amperometry circuit has to have a high sensitivity and high speed with low noise. In this work, a current buffer was inserted to mitigate the potential fluctuation. Three test chips were fabricated using a 0.6-μm CMOS process: two with 1.2 μm × 2.05 μm 1024 × 1024 and 4 μm × 4 μm (16 × 4) sensor arrays and one with 6-μm × 6-μm (16 × 16) sensor arrays; and the microelectrodes were formed on them using electroless plating. The uniformity among the 1024 × 1024 electrodes arranged with a pitch of 3.6 μm × 4.45 μm was optically verified. For improving sensitivity, the trenches on each microelectrode were developed and verified optically and electrochemically for the first time. Higher sensitivity can be achieved by introducing a trench structure than by using a conventional microelectrode formed by contact photolithography. Cyclic voltammetry (CV) measurements obtained using the 1.2 μm × 2.05 μm 16 × 4 and 6-μm × 6-μm 16 × 16 sensor array with electroless-plated microelectrodes successfully demonstrated direct counting of the bacteria-sized microbeads and HeLa cells.
关键词： microelectrode array,point-of-care testing,HeLa cells,electroless plating,Bacteria counting,CMOS
更新于2025-09-19 17:13:59
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[IEEE 2019 Photonics North (PN) - Quebec City, QC, Canada (2019.5.21-2019.5.23)] 2019 Photonics North (PN) - Femtosecond Laser Opening of Hollow-Filament Arrays: the Fiber Bragg Grating Opto-fluidic Sensor
摘要： The development of two new types of high-density, electroless plated microelectrode arrays for CMOS-based high-sensitivity direct bacteria and HeLa cell counting are presented. For emerging high-sensitivity direct pathogen counting, two technical challenges must be addressed. One is the formation of a bacteria-sized microelectrode, and the other is the development of a high-sensitivity and high-speed amperometry circuit. The requirement for microelectrode formation is that the gold microelectrodes are required to be as small as the target cell. By improving a self-aligned electroless plating technique, the dimensions of the microelectrodes on a CMOS sensor chip in this work were successfully reduced to 1.2 μm × 2.05 μm. This is 1/20th of the smallest size reported in the literature. Since a bacteria-sized microelectrode has a severe limitation on the current flow, the amperometry circuit has to have a high sensitivity and high speed with low noise. In this work, a current buffer was inserted to mitigate the potential fluctuation. Three test chips were fabricated using a 0.6-μm CMOS process: two with 1.2 μm × 2.05 μm 1024 × 1024 and 4 μm × 4 μm (16 × 4) sensor arrays and one with 6-μm × 6-μm (16 × 16) sensor arrays; and the microelectrodes were formed on them using electroless plating. The uniformity among the 1024 × 1024 electrodes arranged with a pitch of 3.6 μm × 4.45 μm was optically verified. For improving sensitivity, the trenches on each microelectrode were developed and verified optically and electrochemically for the first time. Higher sensitivity can be achieved by introducing a trench structure than by using a conventional microelectrode formed by contact photolithography. Cyclic voltammetry (CV) measurements obtained using the 1.2 μm × 2.05 μm 16 × 4 and 6-μm × 6-μm 16 × 16 sensor array with electroless-plated microelectrodes successfully demonstrated direct counting of the bacteria-sized microbeads and HeLa cells.
关键词： microelectrode array,point-of-care testing,HeLa cells,electroless plating,Bacteria counting,CMOS
更新于2025-09-19 17:13:59