The development of cost-effective and versatile sensing system for simultaneous and rapid quantitation of multiple targets is highly demanded for environmental surveillance, food safety inspection, ...home healthcare, etc. This work reports on (1) paper-based microarrays relying on fluorescence turn-off of carbon nanodots (CDs) for analyte recognition and (2) a stand-alone smartphone-based portable reader (SBR) installed with a custom-designed APP (SBR-App), which can accurately and reproducibly acquire fluorescence change from the microarray chip, automatically report the results, generate and share the reports via wireless network. Simultaneous detection of Hg2+, Pb2+, and Cu2+ in the Pearl River water samples was achieved with the reported sensing system. End-user operation is limited to pipet samples to the microarray chip, insert the chip to the SBR, and open the SBR-App to acquire an image 5 min after sample introduction. There is no requirement for complicated sample pre-treatment and expensive equipment except for a smartphone. This versatile and cost-effective smartphone-based sensing system featured with reliability and simplicity is ideally suited for user- and eco-friendly point-of-need detection in resource-constrained environments.
The great challenge still exists in the synthesis of red-emissive carbon nanodots (C-dots) and the development of molecular logic devices with better operation stability for biological applications. ...In this study, gadolinium (III)-doped C-dots are synthesized by a new solvothermal approach using citric acid, urea and GdCl3 as precursors. The as-prepared Gd3+-doped C-dots exhibit bright red fluorescence (FL) centered at 620 nm in an excitation wavelength-independent manner, and a high T1 relaxivity (∼16.0 mM−1 s−1). More excitingly, the Gd3+-doped C-dots exhibit a pH-dependent response in not only FL behaviour but also magnetic resonance (MR) signal. When triggered by H+, OH−, or Cu2+, the Gd3+-doped C-dots can behave as a switch for FL emission and MR signal, leading to dual-readout and multi-addressable logic systems. Therefore, by employing the Gd3+-doped C-dots as logic gate with varying the chemical inputs, FL/MR dual-readout logic operations including IMP and NOR have been successfully demonstrated not only in all-aqueous media but also within the living HeLa cells. Together with the good biocompatibility and cell-permeability, the Gd3+-doped C-dots hold great potentials for real-time monitoring pH changes both in solution and biological cells, and even future evaluating cellular states via in-cell biocomputation.
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Multi-modal imaging probes through synergistically combining two or more imaging modalities into single nanoparticle, offer possibilities to address multiple issues such as resolution, sensitivity, ...and tissue penetration. In this study, we report a facile strategy to synthesize a dual-modal fluorescence/magnetic resonance (MR) imaging nanoprobe with bright fluorescence and significantly improved relaxivity, where Gd3+ ions are simply chelated onto the outer surface of the cyclic DTPA dianhydride (cDTPAA) functionalized carbon quantum dots (CQDs). Transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and zeta potential measurements validated the successful preparation of CQD–DTPA–Gd. The surface conjugation of CQDs with cDTPAA and further Gd3+ chelation does not perturb core optical properties of CQDs, and the thus prepared CQD–DTPA–Gd contain minimum Gd3+ content (8.06%, w/w), while exhibiting significantly improved longitudinal relaxivity (56.72mM−1s−1). Excellent water solubility, good cell-membrane permeability and negligible cytotoxicity make CQD–DTPA–Gd an ideal dual-modal fluorescence/MR imaging probe, suggesting its potential and significance in practical bioimaging applications and medical translation in the future.
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•A feasible, portable, and cost-effective smartphone-Based detection system for point-of care food safety inspection.•Excellent reliability and applicability of the detection system ...for ZEN quantitation in cereals and feed.•Novel blue carboxylated LMs coupled to ZEN mAb as the colorimetric indicator.•Facile 3D printing technology was used to manufactured of the smartphone optosensing platform.•A user-friendly APP for automatic image processing, result display, and sharing.
In our study, a 3D printed smartphone-based detection device integrated with solid phase latex microsphere immunochromatography platform (SIAP) is developed for sensitive and quantitative detection of zearalenone (ZEN) in cereals and feed. A user-friendly Android application (App) is self-written to analyze, report and share the detection results. The cut-off values of latex microsphere immunochromatography for ZEN in cereals and feed were 2.5 and 3.0 μg/kg, respectively. The SIAP detection system can quantitatively detect ZEN in cereals and feed with the detection limits of 0.08 and 0.18 μg/kg, respectively. The recovery rates of corn, and feed samples were between 92.0%–105.0%, and 86.0%–107.5%, respectively, with the coefficient of variation ranging from 2.7% to 8.9%, and 7.8 to 10.9%, respectively. The detection results of real samples showed that there were differences in the content of ZEN in different feed ingredients and compound feed in China in October 2018, among which corn and wheat were still the feed ingredients with the most serious ZEN contamination, and it also demonstrated that the established SIAP detection system was reliable, portable, and user-friendly. This smartphone-based detection system will be popularized for on-site monitoring of various hazard factors such as veterinary drugs, antibiotics, illegal additives, etc.
The widespread use of antibiotics caused severe problems of antibiotic residues in foodstuffs and water, posing a serious threat to public health and thus urging the development of sensitive, ...selective, and rapid detection methods for antibiotics. In this study, a fluorescence resonance energy transfer (FRET)-based system is developed for the multiplexed analysis of chloramphenicol (CAP) and streptomycin (Strep) with detection limits of 2.51 and 8.69
g l
, respectively. The FRET-based system consists of Cy3-tagged anti-CAP aptamer-conjugated gold nanoparticles (AuNPs) (referred to as AuNPs-AptCAP) and Cy5-tagged anti-Strep aptamer-conjugated AuNPs (referred to as AuNPs-AptStrep). In addition, AuNPs-AptCAP and AuNPs-AptStrep have been demonstrated to serve as signal transducers for implementing a series of logic operations such as YES, NOT, INH, OR, (2-4)-Decoder and even more complicated multi-level logic gates (OR-INH). Based on the outputs of logic operations, it could be figured out whether targeted analytes were present or not, thus enabling multiplex sensing and evaluation of pollution status. This proof of concept study might provide a new route for the enhanced sensing performance to distinguish different pollution status as well as the design of molecular mimics of logic elements to demonstrate better applicability.
We have proposed a signal dual-amplification electrochemiluminescence (ECL) strategy based on tris(2,2′-bipyridyl)ruthenium(II) (Ru(bpy)32+) as chromophores confined with three-dimensional (3D) zinc ...oxalate metal−organic frameworks (Ru(bpy)32+@MOFs) for the detection of miRNA-21. The three-dimensional chromophore connectivity in zinc oxalate MOFs provided a network among Ru(bpy)32+ units, shielding the chromophores from solvent molecules and resulting in high Ru(II) complex emission efficiency. Additionally, we discovered that magnetic beads (MBs) used as carrier for enriched signals contribute to enhanced ECL intensity of the chromophore. To evaluate its clinical application, we applied this method to determine the concentration of miRNA-21 solutions ranging from 1.56 to 100 nM, obtaining a calibration curve of ECL intensity versus logarithm of concentration (logC) of miRNA-21 with a high correlation coefficient. This work demonstrates the construction of a signal amplification strategy ECL biosensor for miRNA using Ru(bpy)32+@MOF systems and its application in ECL detection for analyte methodology.
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•A smartphone-based ECL device for point-of-need quantitation of the breast cancer tumor marker miRNA-21 was designed.•A signal dual-amplification ECL strategy based on Ru(bpy)32+@MOFs for the sensitive detection of miRNA-21 was developed.•Magnetic beads used as carrier for enriched signals contribute to enhanced ECL intensity of the chromophore.•The sensor was used to detection of miRNA in normal human serum samples.
•The SAFS is developed to collect both absorption and fluorescence spectra anywhere.•The SAFS-App is programmed for spectrum reconstruction and quantitative analysis.•The SAFS exhibits a comparable ...precision in spectrum collection as its laboratory counterparts.•A colorimetric and fluorometric dual-readout assay is designed for xanthine quantitation.•The SAFS exhibits a comparable accuracy in xanthine quantitation as HPLC.
Rapid and quantitative biochemical analysis at points-of-need is imperative for food safety inspection. This work reports on: 1) a stand-alone smartphone-based “two-in-one” spectrophotometer (the SAFS) installed with a self-developed application (the SAFS-App) which can precisely collect both absorption spectra and fluorescence spectra in a reproducible manner within 5 s; and 2) a straightforward protocol for xanthine detection using fluorescent carbon nanodots and silver nanoparticles. The assay performed with the SAFS demonstrates high specificity towards xanthine, and a linear range of 1–60 μM with LODs of 0.38 and 0.58 μM for colorimetric and fluorometric readouts, respectively. The reliability and robustness of the SAFS are validated by on-site quantitation of xanthine in fish and serum samples, with comparable accuracy to HPLC method. More importantly, the SAFS presents itself as an appealing device which is accessible to everyone through the Internet of Things and can be tailored for diverse point-of-care testing applications.
This study reports a smart theranostic probe, designated as DMCR, designed for simultaneous CT/MR/FL imaging and chemo/photothermal synergistic therapy. Gd/I-doped carbon nanodots (designed as ...Gd/I-CDs) are synthesized for the first time using a straightforward one-step solvent thermal approach, serving as the efficient FL/MR/CT trimodal imaging component of DMCR. Subsequently, chemical drug doxorubicin (DOX), diagnostic moiety Gd/I-CDs and tumor-targeting peptide CRGD are successively conjugated onto mesoporous polydopamine (MPDA) to prepare DMCR. Besides its role as versatile scaffold for loading various functional moieties, MPDA serves two additional functions: as an efficient fluorescence quencher for Gd/I-CDs, and an effective photo-sensitizer for photothermal therapy. Therefore, loading DOX into MPDA facilitates the resulting DMCR for chemo/photothermal synergistic tumor therapy. DMCR exhibits excellent water-solubility, biocompatibility, and strong tumor-targeting capability. The decomposition of MPDA by over-expressed glutathione (GSH) and H+ in the tumor microenvironment leads to the GSH/H+-responsive release of diagnostic moieties Gd/I-CDs and therapeutic moieties DOX, triggering the fluorescence turn-on of Gd/I-CDs. In addition, DMCR exhibits a high r1 relaxation rate (38.3 mM−1s−1) and X-ray absorption capability (153.8 Hu mM−1). Both in vitro and in vivo experiments confirm DMCR's high effectiveness in FL/MR/CT triple-modal imaging of tumors and synergistically inhibiting tumor growth with improved efficacy.
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•A rapid and cost-effective smartphone-based method for point-of-need M.tb detection.•Direct and indirect dot-blot assays using the aptamer for M.tb recognition.•Excellent applicability of the ...developed dot-blot assays for M.tb quantitation in sputum samples.•A user-friendly APP for automatic image processing and result display and sharing.
Due to the poor sensitivities and specificities of antibody based point of need devices, we have developed a low-cost and reliable latent tuberculosis infection (LTBI) screening system based on enzyme linked aptamers which are cost effective and chemically stable. Specific recognition of mannose-capped lipoarabinomannan on the surface of Mycobacterium tuberculosis has been achieved for the development of direct and indirect dot-blot approaches which are designed for simultaneous quantitative analysis of multiple samples and identification of mycobacterial strains, respectively. Compared with traditional acid-fast staining assay used for LTBI screening, our direct dot-blot system has offered a lower limit of quantitation at 104CFU/mL and higher accuracy. In contrast to traditional bacterial culture approach which takes 3–5 weeks, our assay can be completed within 5h, which is a remarkable increase in assay efficiency. To maximize the portability and fulfill the needs for LTBI screening in developing countries, an Android application has been developed to carry out colorimetric analysis of images captured by a smartphone camera, followed by generating and sharing of diagnostic reports through internet connectivity. Upon promotion, we believe this low-cost and effective LTBI screening system will control the outspread of tuberculosis and save many lives, particularly in developing countries.
