On-site Visualization Research Articles

Tumor microenvironment-based smart beacon drug delivery system for in situ visualization of tumor therapy

Real-time monitoring of the effectiveness of tumor-targeted drugs is crucial for assessing their impact. To address this need, we developed a beacon drug delivery system, MDB, which incorporates tumor targeting, anti-tumor effects, and near-infrared fluorescence emission for on-site visualization of tumor therapy. In non-cancerous cells, MDB remains inactive as a prodrug but is selectively activated within tumor cells when the borate ester group reacts with H2O2 in the tumor microenvironment (TME), releasing the beacon drug MDBRe. MDBRe can down-regulate the expression of the protein heme oxygenase 1 (HO-1), ultimately disrupting the mitochondrial energy supply system and leading to tumor cell death. It also emits near-infrared fluorescence for drug tracking under structured illumination microscopy (SIM). Both in vitro and in vivo experiments confirm the effective delivery of MDBRe by MDB to H2O2-enriched tumor tissues, resulting in a potent anti-tumor effect, visualization of drug distribution in tumors, and monitoring of therapy progress. In conclusion, our approach presents a novel method for targeted drug delivery to tumors and enables real-time visual monitoring of the treatment process.

On-Site Visualization Assay for Tumor-Associated miRNAs: Using Ru@TiO2 as a Peroxidase-like Nanozyme.

Accurate diagnosis of highly aggressive and deadly tumors is essential for effective treatment and improved patient outcomes, and microRNAs (miRNAs) have emerged as crucial biomarkers for their roles in tumor initiation, progression, and metastasis. Herein, we present an on-site visualization colorimetric assay for tumor-associated miRNAs using ruthenium nanoparticle decorated titanium dioxide nanoribbon (Ru@TiO2) as a peroxidase-like (POD) nanozyme. Remarkably, the Ru@TiO2 nanozyme can catalyze the oxidation of chromogenic substrates through its POD-like activity, which is effectively inhibited by pyrophosphate generated during the rolling circle amplification process, thereby enabling miRNA detection through a visible colorimetric readout. This approach provides a highly sensitive and specificity assay for miRNAs in diluted human serum with a detection limit of 100 pM. It shows great potential for clinical diagnostics and biological research, offering a promising tool for early cancer diagnosis and molecular diagnostics.

AIEE-Active Green Fluorescence Imaging Technique for Latent Fingerprint Application.

Latent fingerprint imaging is a crucial tool for national security and crime recognition, requiring environmentally sustainable, nontoxic materials. To address this need, we have developed a green fluorescence-emitting material, THCHO, that binds effectively to latent fingerprints, enabling clear, high-resolution visualization. The solution produces strong green fluorescence that highlights fingerprint imprints with exceptional detail and contrast. The material is applicable across various substrates, making it efficient for on-site visualization. The synthesized organic conjugated material THCHO rapidly visualizes precise fingerprint substructures within 5 s using a simple spray method. It maintains high contrast and low interference across different substrates, such as glass, aluminum foil, plastic, and ironware, even in diverse backgrounds. Additionally, the THCHO material demonstrates high stability, retaining its fluorescence imaging capabilities for up to 35 days and after water washing. This is the first report of using a conjugated organic thiophene material for latent fingerprint fluorescence imaging, suggesting potential applications in other fields.

New phenanthridine-based multi-functional chemosensor for selective detection of Th4+ and Hg2+ ions in both aqueous and solid state

A new phenanthridine-based multifunctional chemosensor (L), was synthesised via a green synthetic route and characterised using FT-IR, NMR and HRMS analysis. The sensing application of L towards metal ions in both solution and solid-state was studied using UV–vis and fluorescence spectroscopy, which exhibits dual-sensing behaviour for Th4+ and Hg2+ ions with good recyclability. In aqueous acetonitrile, L showed rapid response for the detection of environmental toxic metal ions and has a very low analytical detection limit of 125.5 pM and 1.94 nM for Th4+ and Hg2+ions respectively, which is remarkably lower than the World Health Organization standard. The cation binding property of the L with Th4+ and Hg2+ions was investigated by Job plot, 1H NMR titration, HR-MS and DFT calculation. The in-situ formed ensemble L-Hg2+ was further applied in the naked-eye detection of Cys (Cystine) and His (Histidine) over other common amino acids. The utility of L for real-time detection of Hg2+ and Th4+ ions was explored in various sources of environmental water samples, test paper strips, fingerprint imaging, fluorescent ink and smartphone-assisted sensing techniques, demonstrating the promising on-site visualization of the probe in controlling the toxicity levels in wastewater sources without resorting to expensive instruments.

Controllable Preparation of a Cu NCs@Zn-MOF Hybrid with Dual Emission Induced by an Ion Exchange Strategy for the Detection of Explosives.

The precise synthesis of Cu NCs is a highly desirable and controllable route for the preparation of desired structures and properties, which facilitates the rational design of valuable probes for fluorescence sensing and the understanding of structure-property relationships. Herein, an ion-exchange strategy combined with a bottom-up synthetic approach was utilized in the synthesis process of Cu NCs for the first time, which achieved the controllable synthesis of Cu NCs and in situ anchoring of Cu NCs on the support material HPU-14. The as-prepared Cu NCs@HPU-14-4h not only had a good peroxidase-like property but also exhibited stable dual-emitting fluorescence at 470 and 620 nm. Notably, the peroxidase-like property endowed Cu NCs@HPU-14-4h with the capability of highly sensitive colorimetric detection of H2O2 in a linear concentration from 0.1 to 140 μM (detection limit of 86.7 nM), and a change in the fluorescent color from red to blue could be observed by the naked eye. Furthermore, due to the large overlap between the absorption of 2,4,6-trinitrophenol (TNP) and the excitation band of Cu NCs@HPU-14-4h, TNP could also be detected from 27 types of analogs and common ions with a limit of detection of 68 nM. Finally, a portable hydrogel probe with efficient wipe sampling was fabricated by polyvinyl alcohol (PVA) comprising Cu NCs@HPU-14-4h with the aim of on-site visualization of different explosives. Consequently, the current study not only provides a new idea for the precise synthesis of Cu NCs and their controllable anchoring on support materials but also offers an effective method for predicting H2O2 and TNP.

Nitrogen-doped polydopamine manganese nanoparticles with excellent oxidase-like activity for ultrafast detection of glutathione at room temperature

Glutathione (GSH) is an essential natural antioxidant, and plays a crucial role in the prevention of various diseases. Herein, a nitrogen-doped polydopamine manganese nanoparticle (N-PDA@Mn) was prepared and used as nanozyme sensor for the rapid and colorimetric detection of GSH. N-PDA@Mn demonstrated excellent oxidase-like activity (Km = 0.0841 mM and Vmax = 3.6 × 10-7 MS-1), exhibiting a rapid balance period of < 100 s. N-PDA@Mn could activate dissolved oxygen to primarily generate singlet-oxygen (1O2), which oxidized colorless 3,3′, 5, 5′-tetramethylbenzidine (TMB) to blue oxidized (ox-TMB). Because GSH could rapidly deplete 1O2, an ultrafast and colorimetric strategy was developed for GSH detection based on N-PDA@Mn. The GSH detection range was 0.5–100 μM, and the detection limit was 0.28 µM. Importantly, at room temperature, the detection time was only 30 s, which was short than that of previously reported GSH detection methods. Furthermore, a point-of-care testing (POCT) platform was designed by combining the N-PDA@Mn colorimetric sensor with a smartphone. Use the POCT platform, a broad linear detection range of 0.5–100 μM and a detection limit of 0.40 μM were obtained. Subsequently, the N-PDA@Mn colorimetric sensor and POCT platform were successfully used in the real-time and on-site quantification of GSH in human serum, achieving a high accuracy and good recovery. Therefore, the N-PDA@Mn-based methods could realize the rapid, on-site visualization, and economical detection of GSH, demonstrating their substantial potential for application in practical testing in fields of food and medicine.

A dual-reaction sites fluorescent probe for accurate detection of benzoyl peroxide in food

Benzoyl peroxide (BPO) is widely used as a whitening agent in flour, but excessive intake of BPO will severely endanger human health. To quickly and accurately detect BPO on-site, we have rationally designed a novel fluorescent probe PTPY-BE with dual-reaction sites. PTPY-BE underwent a specific cascade reaction with BPO to achieve high-contrast fluorescence turn-on response along with significant achromic reaction. The probe has high sensitivity, excellent selectivity, strong anti-interference ability and low detection limit (LOD = 0.83 mg·kg−1) for BPO. Furthermore, a portable detection platform was fabricated, which offers the portability and color visualization of traditional test strips and the color recognition of a smart device, enabling on-site visualization and quantitative detection of BPO. This platform has been successfully used to determine BPO in real food samples with good recoveries (93.59% - 107.13%). Therefore, this platform possessed great prospect and potential application for the determination of BPO in food.

A rapid on-site visualization platform based on RPA coupled with CRISPR-Cas12a for the detection of genetically modified papaya ‘Huanong No.1’

The Papaya ringspot virus (PRSV)-resistant genetically modified (GM) papaya ‘Huanong No.1’ has been certified as safe for consumption and widely planted in China for about 18 years. To protect consumers' rights and facilitate government supervision and monitoring, it is necessary to establish a simple, rapid, and specific detection method for ‘Huanong No.1’. Herein, we developed a platform based on recombinase polymerase amplification (RPA) coupled with CRISPR-Cas12a for the detection of ‘Huanong No.1’. The RPA-CRISPR-Cas12a platform was found to have high specificity, with amplification signals only present in ‘Huanong No.1’. Additionally, the platform was highly sensitive, with a limit of detection (LOD) of approximately 20 copies. The detection process was fast and could be completed in less than 1 h. This novel platform enables the rapid on-site visualization detection of ‘Huanong No.1’, eliminating dependence on laboratory conditions and specialized instruments, and can serve as a technical reference for the rapid detection of other GM plants.

Server-enabled mixed reality for flood risk communication: On-site visualization with digital twins and multi-client support

This study introduces a novel mobile mixed reality (MR) system to improve communication among stakeholders regarding climate-change-driven flood risk. This MR system enables stakeholders to visualize flood risks on common mobile devices, such as smartphones and tablets, offering perspectives from their respective environments. The system overcomes the computational limitations of previous mobile MR systems by rendering the MR images on a server. Furthermore, distributing users across multiple servers enables many users to simultaneously perform server-enabled MR, facilitating widespread engagement in flood risk communication. The system uses a viewport transformation to accurately display virtual floods and correct for real-time posture changes. A prototype tested in a high-risk flood area achieved real-time MR visualization at more than 16 frames per second, even on multiple devices. Future research will aim to promote stakeholder participation through more accurate visualization of virtual floods and improved interactive information sharing among users.

(Invited) A Biosensor Platform for on-Site Virus Visualization

Introduction The detection of small amounts of specific targets such as toxins, pathogens, and viruses has become increasingly important since the SARS-CoV-2 pandemic. Particularly, the on-site virus detection by naked eye or camera, which allows direct and rapid visualization of the virus on a surface directly and rapidly, is one of the most appropriate ways to control and prevent from the infection. Currently available technologies for the virus detection such as quantitative PCR, ELISA, and lateral flow immunoassay are useful, but they require complicated sample extractions and sometimes bound/free (B/F) separation procedures, which makes the detection time-consuming and inconvenient. One realistic example of the on-site visualization is a forensic luminol blood test based on chemiluminescence because complicated detection procedures must be eliminated for the on-site visualization. The forensic test is based on the peroxidase activity of hemoglobin for the chemiluminescence emission upon the spraying of hydrogen peroxide solution. Therefore, we focused on generation of hydrogen peroxide in the proximal of virus and the associated emission of chemiluminescence, which enables us to the on-site visualization.To realize the localized hydrogen peroxide generation and successive chemiluminescence emission, we designed sequential enzymatic reactions using oxidase and peroxidase to be occurred only on the viral surface. In detail, we prepared antibody-enzyme complex (AEC) composed of oxidase and anti-virus antibody as a donor, and peroxidase-based molecules with virus-recognition ability as an acceptor. In the presence of virus, the donor and the acceptor bind to the virus, and a hydrogen peroxide relay from the donor and the acceptor on the viral surface will lead to the detection and visualization only after mixing of reagents (Fig.). Here, glucose oxidase (GOx) was used as a model donor enzyme because the substrate, glucose, is safe and highly stable, and conveniently prepared the AEC by SpyCatcher/SpyTag system, a protein coupling module for biosensing1). As the acceptor, bispecific aptamer targeting virus and peroxidase-based molecules was used. Then, we validated the utility of the platform by applying it to the detection and visualization of inactivated SARS-CoV-2. Methods The recombinantly produced SpyTag (ST)-fused anti-SARS-CoV-2 surface protein single-chain variable fragment (scFv-ST) and SpyCatcher (SC)-fused GOx (SC-GOx) were equivalently mixed and incubated at 4℃ to prepare the homogenous AEC. The bivalent AEC can be prepared because the GOx forms homo-dimer. The enzymatic activity and affinity were evaluated. Then, we constructed the detection systems using different peroxidase-based molecules as acceptors, and applied them to inactivated SARS-CoV-2 detection and visualization using a conventional smartphone camera. Results & Discussion SDS-PAGE analysis revealed that the AEC was prepared by only mixing of scFv-ST and SC-GOx via the SpyCatcher/SpyTag reaction. The AEC showed high binding ability, and K D values of scFv-ST and the AEC were 32 nM and 19 nM, respectively. This affinity enhancement was caused by the bivalency of the AEC. The AEC showed 72% of oxidase activity compared to the original GOx, suggested that the AEC retained sufficient activity for the signal generation as the donor.As the acceptor, myoglobin (Mb) and a bispecific aptamer composed of Mb aptamer2) and SARS-CoV-2 surface protein binding aptamer were used. The peroxidase activity of Mb is relatively weak, so a reduced decreased background signal is expected. The bispecific aptamer showed binding abilities to Mb and inactivated SARS-CoV-2.Using these detection components, we successfully detected inactivated SARS-CoV-2 by only mixing of the components, and the linear detection range met the clinically required level. Owing to the sequential enzymatic reactions only on the viral surface, the rapid detection system without any washing procedures was established. By exchanging a set of antibody and aptamer, it was applied to inactivated influenza A virus detection.Finally, hemin and hemin-binding aptamer were used as the acceptor and applied it to the inactivated SARS-CoV-2 visualization. As a result, not only the viruses in a 96-well plate but also on a nitrocellulose membrane was visualized by luminol-derived chemiluminescence through a conventional smartphone camera. This was a first report of the on-site virus visualization. In addition, the use of sequential enzymatic reaction provides the signal amplification when applied to electrochemical detection3), leading to more rapid and convenient detection using established portable devices. This system can be a platform for control of infection in public space in the future. References 1) D. Miura et al., Talanta, 234, 122638 (2021).2) K. Tsukakoshi et al., Nucleic Acid Res., 49, 6069-6081 (2021).3) B. Jeong et al., Anal. Chem., 85, 1784-1791 (2013). Figure 1

Peptide-based probe for colorimetric and fluorescent detection of Cu2+ and S2- in environmental and biological systems

Pollution caused by Copper and hydrogen sulfide pollution has severe adverse effects on the environment and organisms. Real-time, fast and accurate monitoring of Cu2+ and S2- faces serious challenges. In this study, we designed a novel biosensor and synthesized it by mimicking the structure of the main Cu(II)-binding site on bovine serum albumin. As a peptide-based sensor, FGGH (FITC-Gly-Gly-His-NH2) can perform the sequential detection of Cu2+ and S2– by fluorescence and colorimetry. The high water solubility and selectivity make it suitable for monitoring Cu2+ and S2– in environmental water samples with high sensitivity; its limit of detection (LOD) is as low as 1.42 nM for Cu2+ and 22.2 nM for S2–. The paper-based sensing platform of this probe was found to be a promising tool for the on-site visualization of real-time quantitative analysis of Cu2+ and S2– due to its rapid response and recyclable detection characteristics. Additionally, FGGH was successfully used to image Cu2+ and S2– in living cells and zebrafish models with adequate fluorescence stability and low cytotoxicity, providing the first visual evidence of the effect of the interactions between Cu2+ and S2– on the redox homeostasis of organisms.

Investigating the Impact of Augmented Reality and BIM on Retrofitting Training for Non-experts.

Augmented Reality (AR) tools have shown significant potential in providing on-site visualization of Building Information Modeling (BIM) data and models for supporting construction evaluation, inspection, and guidance. Retrofitting existing buildings, however, remains a challenging task requiring more innovative solutions to successfully integrate AR and BIM. This study aims to investigate the impact of AR+BIM technology on the retrofitting training process and assess the potential for future on-site usage. We conducted a study with 64 non-expert participants, who were asked to perform a common retrofitting procedure of an electrical outlet installation using either an AR+BIM system or a standard printed blueprint documentation set. Our findings indicate that AR+BIM reduced task time significantly and improved performance consistency across participants, while also decreasing the physical and cognitive demands of the training. This study provides a foundation for augmenting future retrofitting construction research that can extend the use of AR+BIM technology, thus facilitating more efficient retrofitting of existing buildings. A video presentation of this article and all supplemental materials are available at https://github.com/DesignLabUCF/SENSEable/_RetrofittingTraining.

Synthesis of Fluorophore Based Functional Material for Selective Detection of Al3+ Ion in Water and Decoding the AIEE Property of Its Hydrosol.

A designed aggregation-induced emission enhancement (AIEE) active fluorescence probe 2,3-Bis-[(2-hydroxy-napthalen-1-ylmethylene)-amino]-but-2-enedinitrile (L) was synthesized via one step condensation method. The probe shows swift sensitivity and selectivity toward Al3+over other relevant metal ions and also exhibits significant AIEE phenomena in methanol/water mixture. Significant enhancement of fluorescence intensity is triggered via chelation-enhanced fluorescence through complex (Al3+-L) formation. A 2:1 metal to ligand ratio is observed from Job's plot based on UV - Vis absorption titration and detection limit (LOD) is found as low as 31.14nM. Moreover, 1H NMR titrations and fluorescence reversibility by adding Al3+ and EDTA sequentially had been performed to establish the binding site of sensor complex (Al3+-L). Time-resolved photoluminescence, dynamic light scattering, optical microscopy, and on-site visualization studies have been performed to understand the AIEE mechanism of L in different volume percentage of water and methanol mixture. An INHIBIT molecular logic gate has been constructed utilizing the fluorescence behavior of the probe, L in presence of Al3+ and strong chelating ligand EDTA.

A Robust Ratiometric Fluorescent Sensor Based on Covalent Assembly of Dipeptides and Biomolecules for the High-Sensitive and Optosmart Detection of Pyrethroids.

In this study, two ultrashort dipeptides, diphenylalanine (FF) or C-terminal amidated diphenylalanine (DPA), were covalently self-assembled with genipin to obtain two well-defined supramolecular peptide nanoparticles for the detection of pyrethroids. DPA-genipin nanoparticles (PNPs) demonstrated excellent dual-emission fluorescence characteristics, tunable particle size, and robust photostability. Parallel to this, PNPs showed a ratiometric fluorescence response to λ-cyhalothrin (LC) with a distinct green-to-red color transition. The satisfactory self-calibration capability of the ratiometric system enabled PNPs to respond sensitively to LC in a wide range (5-800 μg/L) with a lower limit of detection of 0.034 μg/L. The introduction of a smartphone application made it easy to develop an intelligent evaluation platform based on PNPs, which had been proven to be applicable for on-site visualization of LC in agricultural products. The platform proposed here may be a new application of peptide self-assembly in sensing, with both important food safety implications and great economic value.

A portable test strip fabricated of luminescent lanthanide-functionalized metal-organic frameworks for rapid and visual detection of tetracycline antibiotics.

Tetracycline antibiotics (TCs) are commonly used antibiotics in the treatment of infections, but their overuse has a negative impact on human health and ecosystems. Thus, the development of a facile and on-site visualization method for TC detection is necessary. Here, we propose the potential of using lanthanide-functionalized metal-organic framework (MOF) composites (Ag+/Tb3+@UiO-66-(COOH)2, ATUC) as a probe for the rapid detection of tetracycline (TC), chlortetracycline (CTC), oxytetracycline (OTC), and doxycycline (DOX) residues, in which UiO-66-(COOH)2 (UC) could be utilized to provide an interaction microenvironment, Tb3+ as recognition units and Ag+ as a fluorescence enhancer. Upon exposure to TCs, significant luminescence quenching of ATUC excited at 255 nm was observed due to the inner filter effect (IFE) and photo-induced electron transfer (PET), and the established strategy has a detection limit (LOD) of 11.0, 20.1, 9.1, and 22.5 nM for TC, CTC, OTC, and DOX, respectively. More importantly, given its portability and conspicuous luminescence color gradation variation, a portable test strip based on ATUC was manufactured and the results could be distinguished immediately by the naked eye and smartphone analysis, allowing for on-site rapid quantitative assay of TCs, not only in the laboratory but also in a point-of-care setting.

An integrated microfluidic device for the simultaneous detection of multiple antibiotics

Residual antibiotics in food pose a serious long-term threat to human health. Therefore, an on-site visualization method for antibiotic detection is required. However, the requirements of traditional antibiotic testing methods in terms of operator proficiency and equipment cost hinder the rapid point-of-care-testing detection of suspected samples. Herein, we reported an integrated microfluidic device combining a microfluidic chip containing cruciform valves with immunochromatographic strips for the rapid detection of multiple antibiotics in milk. The rapid qualitative and quantitative analysis of four types of antibiotics (sulfonamides, β-lactams, streptomycin, and tetracyclines) was performed using mobile phone photography and mobile phone application analysis. The detection time was maintained at 10 min. The limits of detection (LODs) for the four antibiotics were 0.15, 0.12, 0.25, and 0.29 ng/mL, respectively, and the selectivity for the different antibiotics was observed even in a highly complex matrix. This device successfully integrated separation and real-time detection onto a chip and might provide a promising perspective for the detection of multiple antibiotics in milk.

Reversible adhesive hydrogel with enhanced sampling efficiency boosted by hydrogen bond and van der Waals force for visualized detection

It is extremely attractive to introduce reversible adhesive hydrogel into the field of sampling wipe for enhancing the sampling efficiency, which facilitates the development of understanding in fundamental science and technology innovation including interfacial interaction, flexible sensor, visualized detection and so forth. Here, a polyacrylic acid/polyvinyl alcohol-borax (PAA/PVA-B) hydrogel is proposed by introducing double-network microstructure for enhancing cohesive strength, and numerous carboxyl, hydroxyl groups as well as borax for facilitating the hydrogen and dynamic borate bond formation, ensuring its reversible adhesive capability. Benefitting from the noncovalent and dynamic covalent bonds, excellent reversible adhesion to diverse surfaces for 50 cycles without apparently decreasing the adhesive force, and high transfer efficiency of stamp patterns (about 99.8%) are successfully achieved. More importantly, efficient wipe sampling in various scenarios by the PAA/PVA-B hydrogel toward the microparticulates of three representative explosives, including military explosive of 2,4,6-trinitrotoluene (TNT, 0.6 µg) and 2,4-dinitrotoluene (DNT, 1.2 µg), improvised explosive of sulfur (S, 16 µg) could be consolidated owing to the hydrogen bonds and van der Waals force. Inspired by on-site visualization of microgramme-level explosives with this PAA/PVA-B hydrogel-based colorimetric sensor, it is expected that the present strategy could not only deepen the insights of interfacial interaction but also stretch the field of both hydrogel and sampling method to new level.

Intraoperative cytopathology of thoracic surgery (ICTS). A captivating, worthwhile, and rewarding service line.

Intraoperative cytopathology for thoracic surgeons is a service that has not been utilized to its full potential in most institutions. It has the advantage of a rapid turnaround time, low costs, high accuracy, real time communication with the surgeon, on-site visualization of the lesion before excision, simplicity, and safety. Our experience, common cytologic findings of the most frequent thoracic tumors encountered during ICTS, hints about the service, and models for implementation and maintenance are presented. This review is aimed to present our experience and perspective about intraoperative cytopathology for thoracic surgeons.

Push-pull electronic effects on benzothiazole derived probes for the detection of Zn2+: Exploring the sensing strategies and its applications

The diverse polarity of electron-donating 4-(diethylamino)salicylaldehyde (S-D), and electron-withdrawing 4-nitrosalicylaldehyde (S–W) were conjugated with benzothiazole (BT) to develop BTS-D and BTS-W probes, respectively. The probes exhibited the excited-state intramolecular proton transfer and intramolecular charge transfer sensing mechanisms in detecting Zn2+. BTS-D and BTS-W achieved a quantitative detection of Zn2+ followed by a strong cyan to green in the emission spectra, and from colorless to yellow in the UV–Vis spectra, respectively. The sensing pathways and coordination affinities between the probes and Zn2+ were explored using a series of spectroscopic evaluations, 1H NMR, 1H–1H COSY (2D NMR), HR–MS, XPS and DFT calculations. The probes demonstrated excellent selectivity, good water solubility, and high sensitivity, securing low LOD values: 0.15 μM for BTS-W in colorimetric analysis and 14 nM for BTS-D in fluorimetric analysis in aqueous media. The advantages of the probes assessed for the detection of Zn2+ in various water samples, Whatman paper-based sensor strips, and PC3 live cells. The findings revealed the encouraging on-site visualization in wastewater systems and bio-contents.

Rapid colorimetric and ratiometric fluorescence method for on-site detection and visualization of phosgene by amino-functionalized carbon dot-based portable droplet system

Phosgene is a very dangerous but important industrial intermediate and is a significant threat to public health. There is, therefore, an urgent need to develop a rapid, visual, and on-site detection method for phosgene. Sensitive and selective phosgene responsive carbon dots (CDs) were synthesized by employing 2-nitro-4-aminodiphenylamine as precursors. The amine group of the CDs can interact selectively with phosgene to effect acylation reactions, which cause color changes from yellow to amaranth and remarkable changes in fluorescence from bright yellow to orange-red due to modification of the CDs’ intramolecular charge transfer (ICT) process. The CDs exhibited fast response (<2 s) for detection of phosgene with an ultralow detection limit (0.63 nM). Furthermore, a portable CD/polystyrene droplet system was developed for rapid and on-site visualization of phosgene. Specifically, the droplet system not only can realize rapid on-spot visual inspection of gaseous phosgene in the liquid phase with the naked eye, but also could make long-term visualization in the solid phase via a polystyrene membrane after solvent volatilization. This study has expanded the scope for application of CDs in sensing field, and provides a new and effective strategy for fabrication excellent platform for real-time detection of phosgene leakage in industrial and public safety applications.