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•A quantitative POCT system is developed for simultaneous detection of multiple metal ions.•The system consists of a hand-held electrochemical analyzer, a smartphone, and a customized ...SPCE.•The customized SPCE was prepared by successive modification of SPCE with rGO, the SMOF and PEI.•Smartphones installed with APP DHMI can realize two-way communication with electrochemical analyzer.•Quantitation results of this POCT system correlate well with ICP-MS measurements.
It is of great significance to develop versatile and cost-effective point-of-care testing (POCT) systems for simultaneous quantitation of multiple analytes on-site. This work reports on: 1) the customized electrodes which exhibit good analytical performance for simultaneous detection of Cd2+, Cu2+, Hg2+, Pb2+ with low detection limits (Cd2+, 0.296 μM; Cu2+, 0.055 μM; Hg2+, 0.351 μM; and Pb2+, 0.025 μM) and wide dynamic ranges (Cd2+, 0.50–12.5 μM; Cu2+, 0.10–9.50 μM; Hg2+, 0.50–12.5 μM; and Pb2+, 0.10–12.5 μM) using differential pulse voltammetry (DPV) measurements. 2) a hand-held electrochemical analyzer which can realize two-way communication with a smartphone and implement DPV measurements; its cost, weight and power consumption are ~$10.0, ~30 g and ~ 253 mW, respectively; 3) a self-developed APP DHMI which can control the analyzer, receive data from the analyzer, and plot the voltammograms on smartphone’s screen in real-time. This quantitative POCT system has been successfully demonstrated for simultaneous quantitation of Cd2+, Cu2+, Hg2+, Pb2+ in tap water, mineral water and Pearl River water, and the quantitation results correlated well with ICP-MS measurements. The features of cost-effectiveness, ease-to-use and reliability make this quantitative POCT system useful for on-site monitoring of multiple heavy metal ions, especially in resource-constrained environments.
Nanoparticles have drawn significant attention in biomedicine due to their unique optical, thermal, magnetic and electrical properties which are highly related to their size and morphologies. ...Recently, microfluidic systems have shown promising potential to modulate critical stages in nanosynthesis, such as nucleation, growth and reaction conditions so that the size, size distribution, morphology, and reproducibility of nanoparticles are optimized in a high throughput manner. In this review, we put an emphasis on a decade of developments of microfluidic systems for engineering nanoparticles in various applications including imaging, biosensing, drug delivery, and theranostic applications.
Glutathione (GSH) plays key roles in biological systems and serves many cellular functions. Since biothiols all incorporate thiol, carboxylic and amino groups, discriminative detection of GSH over ...cysteine (Cys) and homocysteine (Hcy) is still challenging. We herein report a dual-mode nanosensor with both colorimetric and fluorometric readout based on carbon quantum dots and gold nanoparticles for discriminative detection of GSH over Cys/Hcy. The proposed sensing system consists of AuNPs and fluorescent carbon quantum dots (CQDs), where CQDs function as fluorometric reporter, and AuNPs serve a dual function as colorimetric reporter and fluorescence quencher. The mechanism of the nanosensor is based on two distance-dependent phenomenons, color change of AuNPs and FRET. Through controlling the surface properties of as-prepared nanoparticles, the addition of CQDs into AuNPs colloid solution might induce the aggregation of AuNPs and CQDs, leading to AuNPs color changing from red to blue and CQDs fluorescence quench. However, the presence of GSH can protect AuNPs from being aggregated and enlarge the inter-particle distance, which subsequently produces color change and fluorescent signal recovery. The nanosensor described in this report reflects on its simplicity and flexibility, where no further surface functionalization is required for the as-prepared nanoparticles, leading to less laborious and more cost-effective synthesis. The proposed dual-mode nanosensor demonstrated highly selectivity toward GSH, and allows the detection of GSH as low as 50nM. More importantly, the nanosensor could not only function in aqueous solution for GSH detection with high sensitivity but also exhibit sensitive responses toward GSH in complicated biological environments, demonstrating its potential in bioanalysis and biodection, which might be significant in disease diagnosis in the future.
●A dual-mode nanosensor for discriminative GSH detection with high sensitivity.●The nanosensor consists of AuNPs and fluorescent CQDs.●Color change of AuNPs and FRET form the basis of the nanosensor.●The label-free nanosensor is simple and flexible.●The nanosensor could function in complicated biological fluids.
Understanding the interaction mechanisms between nanomaterials and biological cells is important for the control and manipulation of these interactions for biomedical applications. In this study, we ...investigated the cellular effects of gold nanoparticles (AuNPs) on the differentiation of mesenchymal stem cells (MSCs) and the associated molecular mechanisms. The results showed that AuNPs promoted the differentiation of MSCs toward osteoblast cells over adipocyte cells by inducing an enhanced osteogenic transcriptional profile and an attenuated adipogenic transcriptional profile. AuNPs exerted the effects by interacting with the cell membrane and binding with proteins in the cytoplasm, causing mechanical stress on the MSCs to activate p38 mitogen-activated protein kinase pathway (MAPK) signaling pathway, which regulates the expression of relevant genes to induce osteogenic differentiation and inhibit adipogenic differentiation.
Obtaining tunable photoluminescence (PL) with improved emission properties is crucial for successfully implementing fluorescent carbon nanodots (fCDs) in all practical applications such as ...multicolour imaging and multiplexed detection by a single excitation wavelength. In this study, we report a facile hydrothermal approach to adjust the PL peaks of fCDs from blue, green to orange by controlling the surface passivation reaction during the synthesis. This is achieved by tuning the passivating reagents in a step-by-step manner. The as-prepared fCDs with narrow size distribution show improved PL properties with different emission wavelengths. Detailed characterization of fCDs using elemental analysis, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy suggested that the surface chemical composition results in this tunable PL emission. Surface passivation significantly alters the surface status, resulting in fCDs with either stronger surface oxidation or N element doping that ultimately determine their PL properties. Further experiments suggested that the as-prepared orange luminescent fCDs (O-fCDs) were sensitive and specific nanosensing platforms towards Fe(3+) determination in a complex biological environment, emphasizing their potential practical applications in clinical and biological fields.
Multipotent mesenchymal stem cells (MSCs) have attracted substantial attention in stem cell therapy and tissue engineering due to their ability to be cultured for successive passages and multilineage ...differentiation. Carbon nanotubes (CNTs) have been proposed to be used as potential biomedical structures for bone formation. Therefore, it is important to study the mechanisms of interaction between MSCs and CNTs. We demonstrated that carboxylated single-walled carbon nanotubes (SWCNTs) and carboxylated multiwalled carbon nanotubes (MWCNTs) inhibited the proliferation, osteogenic differentiation, adipogenic differentiation, and mineralization of MSCs. Oxidative stress assay indicated that reactive oxygen species (ROS) may not be responsible for the observed cytotoxicity of carboxylated CNTs. Quantitative real-time polymerase chain reaction (Q-PCR) experiments confirmed that the expression of osteoblast specific genes and adipocyte differentiation specific genes was greatly attenuated during the differentiation of MSCs in the presence of carboxylated CNTs. TEM images revealed that CNTs might interact with proteins located on the cell membrane or in the cytoplasm, which have a further impact on subsequent cellular signaling pathways. Q-PCR results and Western blot analysis together verified that the inhibition of proliferation and osteogenic differentiation of MSCs may be modulated through a Smad-dependent bone morphogenetic protein (BMP) signaling pathway.
The pivotal role of microfluidic technology in life science and biomedical research is now widely recognized. Indeed, microfluidics as a research tool is unparalleled in terms of its ...biocompatibility, robustness, efficient reagent consumption, and controlled fluidic, surface, and structure environments. The controlled environments are essential in assessing the complex behavior of cells in response to microenvironmental cues. The strengths of microfluidics also reside in its amenability to integration with other analytical platforms and its capacity for miniaturization, parallelization and automation of biochemical assays. Following previous review on the applications of microfluidic devices for cell-based assays in 2006, we have monitored the progress in the field and summarized the advances in microfluidic technology from 2007 to 2017, with a focus on microfluidics development for applications in cell manipulation, cell capture and detection, and cell treatment and analysis. Moreover, we highlighted novel commercial microfluidic products for biomedical and clinical purposes that were introduced in the review period. Thus, this review provides a comprehensive source for recent developments in microfluidics and presents a snapshot of its remarkable contribution towards basic biomedical research and clinical science. We recognize that although enormous amounts of evidence have reinforced the promise of microfluidic technology across diverse applications, much remains to be done to realize its full potential in mainstream biomedical science and clinical practice.
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•Advances in microfluidic technology for cell analysis in the last decade were reviewed.•Microfluidic platforms exhibited superior spatiotemporal resolution for cell manipulation and monitoring of cellular responses..•Commercialization of microfluidic technology has gained traction in biomedical research and diagnostic applications. .
Infectious virus outbreaks pose a significant challenge to public healthcare systems. Early and accurate virus diagnosis is critical to prevent the spread of the virus, especially when no specific ...vaccine or effective medicine is available. In clinics, the most commonly used viral detection methods are molecular techniques that involve the measurement of nucleic acids or proteins biomarkers. However, most clinic‐based methods require complex infrastructure and expensive equipment, which are not suitable for low‐resource settings. Over the past years, smartphone‐based point‐of‐care testing (POCT) has rapidly emerged as a potential alternative to laboratory‐based clinical diagnosis. This review summarizes the latest development of virus detection. First, laboratory‐based and POCT‐based viral diagnostic techniques are compared, both of which rely on immunosensing and nucleic acid detection. Then, various smartphone‐based POCT diagnostic techniques, including optical biosensors, electrochemical biosensors, and other types of biosensors are discussed. Moreover, this review covers the development of smartphone‐based POCT diagnostics for various viruses including COVID‐19, Ebola, influenza, Zika, HIV, et al. Finally, the prospects and challenges of smartphone‐based POCT diagnostics are discussed. It is believed that this review will aid researchers better understand the current challenges and prospects for achieving the ultimate goal of containing disease‐causing viruses worldwide.
This review summarizes the latest development of virus detection techniques, with the special focus on smartphone‐based viral diagnostics whose advances have enabled laboratory‐based molecular detections to be performed with plug‐and‐play stand‐alone devices. Discussion on challenges and future perspectives of smartphone‐based viral diagnostics is highlighted, which might push the development of mobile diagnostics forward with scientific and available guidance.
The development of cost-effective, portable, and ease-of-use sensing system for on-site genetic diagnostics is highly desirable for pathogen screening and infectious disease diagnosis. This study ...develops (1) a paper-based biochip which is able to integrate the loop-mediated isothermal amplification (LAMP) protocols for simultaneous detection of
Escherichia coli
O157:H7,
Salmonella
spp., and
Staphylococcus aureus
, and (2) a stand-alone smartphone-based portable device which can control exactly 65 °C for isothermal amplification as well as collect and analyze the thus generated fluorescence signals. The reported sensing system has been successfully demonstrated for foodborne pathogen detection with a limit of detection of 2.8 × 10
−5
ng μL
−1
. Spiked milk samples with concentration as low as 10 CFU mL
−1
were successfully determined within 4 h, demonstrating the practicality of the reported sensing system in the fields. The reported sensing system featuring simplicity and reliability is ideally suited for genetic diagnostics in low resource settings.
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A novel dual-functional nanoprobe was designed and synthesized by facile assembly of quinoline derivative (PEIQ) and meso-tetra (4-carboxyphenyl) porphine (TCPP) via electrostatic interaction for ...simultaneous sensing of fluorescence of Zn
2+
and pH. Under the single-wavelength excitation at 400 nm, this nanoprobe not only exhibits “OFF-ON” green fluorescence at 512 nm by specific PEIQ-Zn
2+
chelation, but also presents red fluorescence enhancement at 654 nm by H
+
-triggered TCPP release. The nanoprobe demonstrated excellent sensing performance with a good linear range (Zn
2+
, 1–40 μM; pH, 5.0–8.0), low detection limit (Zn
2+
, 0.88 μM), and simultaneous response towards Zn
2+
and pH in pure aqueous solution within 2 min. More importantly, this dual-functional nanoprobe demonstrates the capability of discerning cancerous cells from normal cells, as evidenced by the fact that cancerous HepG2 cells in tumor microenvironment exhibit substantially higher red fluorescence and significantly lower green fluorescence than normal HL-7702 cells. The simultaneous, real-time fluorescence imaging of multiple analytes in a living system could be significant for cell analysis and tracking, cancer diagnosis, and even fluorescence-guided surgery of tumors.
Graphical abstract
