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Accumulated evidence has shown that Balkan endemic nephropathy (BEN) is a multifactorial environmental disease, with exposure to aristolochic acids (AA), and the associated DNA adduct formation, as a key causative factor of BEN development. Here, we show that coexposure to arsenic, cadmium, and iron increases the DNA adduct formation of AA in cultured kidney cells, while exhibiting both an exposure concentration and duration dependence. In contrast, coexposure to calcium and copper showed a decreasing DNA adduct formation. Because DNA damage is responsible for both the nephrotoxicity and carcinogenicity of AA, these results shed greater light on the endemic nature of BEN. © 2024 American Chemical Society.

The synthesis of Cs2AgIn0.9Bi0.1Cl6 nanocrystals was achieved at room temperature under ambient conditions using the ligand-assisted reprecipitation (LARP) method. The synthesized NCs exhibit bright orange emission when excited at 375 nm and have broad photoluminescence (PL) emission spectra with a maximum of 630 nm. A photoluminescence quantum yield (PLQY) of 36% was observed in these NCs without any polymer coatings. Polystyrene (PS), and poly (methyl methacrylate) (PMMA) were used to enhance the water stability and PLQY values up to 64%. Nanocomposite thin films with these polymer encapsulations exhibit good thermal stability up to at least 353 K and high quantum yields. PMMA-coated NCs showed long-term water stability for at least 4 months. The composites remain photostable when in contact with water for at least 120 min under continuous 365 nm UV illumination at 1 mW cm−2. Due to their excellent optical properties, aqueous stability, and wide range pH tolerance, these nanocomposite thin films could be employed for a variety of biological applications.

Droplet microfluidic technology facilitates the development of high-throughput screening applications in nanoliter volumes. Surfactants provide stability for emulsified monodisperse droplets to carry out compartmentalization. Fluorinated silica-based nanoparticles are used; they can minimize crosstalk in microdroplets and provide further functionalities by surface labeling. Here we describe a protocol for monitoring pH changes in live single cells by fluorinated silica nanoparticles, for their synthesis, chip fabrication, and optical monitoring on the microscale. The nanoparticles are doped with ruthenium-tris-1,10-phenanthroline dichloride on the inside and conjugated with fluorescein isothiocyanate on the surface. This protocol may be used more generally to detect pH changes in microdroplets. The fluorinated silica nanoparticles can also be used as droplet stabilizers with an integrated luminescent sensor for other applications.

In this work, we demonstrate an inexpensive method of prototyping microfluidics using a desktop injection molding machine. A centrifugal microfluidic device with a novel central filling mechanism was developed to demonstrate the technique. We overcame the limitations of desktop machines in replicating microfluidic features by variotherm heating and cooling the mold between 50 & DEG;C and 110 & DEG;C within two minutes. Variotherm heating enabled good replication of microfeatures, with a coefficient of variation averaging only 3.6% attained for the measured widths of 100 & mu;m wide molded channels. Using this methodology, we produced functional polystyrene centrifugal microfluidic chips, capable of aliquoting fluids into 5.0 & mu;L reaction chambers with 97.5% accuracy. We performed allele-specific loop-mediated isothermal amplification (AS-LAMP) reactions for genotyping CYP2C19 alleles on these chips. Readouts were generated using optical pH sensors integrated onto chips, by drop-casting sensor precursor solutions into reaction chambers before final chip assembly. Positive reactions could be discerned by decreases in pH sensor fluorescence, thresholded against negative control reactions lacking the primers for nucleic acid amplification and with time-to-results averaging 38 minutes. Variotherm desktop injection molding can enable researchers to prototype microfluidic devices more cost-effectively, in an iterative fashion, due to reduced costs of smaller, in-house molds. Designs prototyped this way can be directly translated to mass production, enhancing their commercialization potential and positive impacts.

Cytokine monitoring has attracted great attention due to its significance in the diagnosis and treatment of many diseases, such as tumors, microbial infections, and immunological diseases. Enzyme-linked immunosorbent assay (ELISA) is one of the most popular methods in cytokine detection, ascribing to the lavish signal amplification methods in the ELISA platform. In addition to classical enzymes, other signal amplifiers such as fluorescent probes, artificial nano-enzymes, and photothermal reagents have been applied to reduce the detection limit and produce more sensitive ELISA kits. Due to the accumulative effect of heat, photothermal reagents are promising materials in the signal amplification of ELISA. However, the lack of efficient photothermal generation material at an aggregate scale may delay the further development of this area. In this contribution, based on an efficient organic photothermal aggregate material, an enzyme-free photothermally amplified fluorescent immunosorbent assay system consisting of an assay microfluidic chip and detecting platform was developed. The photothermal nanoparticles with highly efficient photothermal conversion by harvesting energy via excited-state intramolecular motions and enlarging molar absorptivity were successfully prepared. The detection concentration at 50 pg/mL of interleukin-2 was achieved, realizing a signal improvement of detection limits by 20-fold compared to that of previously reported photothermal ELISA. The microscopic imaging integrated with plane sweeping technology provided high spatial resolution and precision, indicating the potential of achieving high throughput profiling at the microscale. Moreover, as an alternative excitation source, light-emitting diode not only provided a more affordable and miniaturized detection system but also revealed the great feasibility of intramolecular motion-induced photothermy nanoparticles for biological analyses. © 2023 The Authors. Aggregate published by SCUT, AIEI, and

Hyflon AD 60 and dodecafluoroheptylpropyl-trihydroxysilane are employed as ligands to synthesize water-stable core-shell CsPbBr3/Cs4PbBr6nanocrystals in aqueous dispersion, with a high photoluminescence quantum yield of 73% and a long luminescence lifetime of 207 ns. The obtained CsPbBr3/Cs4PbBr6NCs passivated by fluorinated ligands are well dispersed in water with a mean diameter of 21.9 nm. The whole synthesis can be performed at room temperature on air; fluorinated chains of the Hyflon ligand strongly bond on the surface of CsPbBr3/Cs4PbBr6nanocrystals and further link amphiphilic fluorinated silanol molecules through hydrophobic interactions. CsPbBr3/Cs4PbBr6nanocrystals are stable in the aqueous phase for at least 1 month, maintaining strong photoluminescence (68% of initial intensity after 31 days) because of surface passivation. They are used as a luminescent temperature probe in water with a sensitivity of its intensity equal to 1.01% K-1and good thermal stability for 10 heating-cooling cycles between 278 and 328 K. © 2022 American Chemical Society. All rights reserved.

Fluorinated silica nanoparticles doped with Ruthenium-tris-1,10-phenanthroline dichloride on the inside and covalently conjugated with perfluorooctyltriethoxysilane and fluorescein isothiocyanate on the outside were developed and served several functions; the fluorination of the particles served to stabilize droplets in a microfluidic system at their interface to the continuous phase for single-cell experiments, and the two dyes provided for intrinsically referenced pH readout according to the time-domain dual lifetime referencing scheme. Apart from eliminating the droplet-to-droplet transport, these nanoparticles at the interface of the droplets generated rigid substrates that were suitable for the proliferation of adherent cells in the droplets without additional matrices. Cancer and non-cancer cell lines with culture media were allowed to proliferate in the droplets and the extracellular pH was monitored. These nanoparticles used in a microdroplet system could measure the pH of the extracellular microenvironment of single cells and provide support for the growth of cells in droplets of around 50 mu m diameter. The pH(e) showed 6.84 +/- 0.04 and 6.81 +/- 0.04 for cancer cells (MCF-7 and A549, respectively) and 7.36 +/- 0.03 for healthy cells (HUVEC), after a 10-h incubation, which can be potentially applied in distinguishing tumor from non-tumor cells. Capable of assisting cell culture and pH sensing in droplet microfluidic systems, the dye-conjugated fluorinated nanoparticles described in this work offer possibilities in a variety of biochemical or environmental analytical applications.

Infectious diseases cause morbidity and mortality worldwide, with the COVID-19 pandemic, caused by a coronavirus, underscoring this fact. Rapidly mutating and proliferating infectious agents perpetuate the threat of future pandemics, making pathogen monitoring imperative; however, a lack of scalable and convenient multiplexed diagnostic technologies makes this challenging. To address this deficit, new methods and technologies for nucleic acid diagnostics were investigated in this work. Centrifugal microfluidic chips were developed which aliquoted liquid to multiple reaction chambers with 97.5% accuracy. These chips were fabricated using variotherm desktop injection molding, a method innovated in this project capable of faithfully molding 100-micron wide channels with a coefficient of variation averaging only 3.6%. Microfluidic designs prototyped using this method are guaranteed scalable, since they can be mass-manufactured with minimal alteration via industrial injection molding. Loop-mediated isothermal amplification (LAMP) and reverse transcription LAMP (RT-LAMP) were used for detecting DNA and RNA fragments, respectively. A colorimetric method for SARS-CoV-2 detection was initially developed utilizing triarylmethane dyes for assay readouts and had a limit of detection of 170 RNA copies per reaction. Next, halochromic indicators were used to generate readouts in minimally buffered RT-LAMP reactions, followed by the novel usage of fluorescent pH sensors comprising poly(2-hydroxyethyl methacrylate) conjugated with fluorescein isothiocyanate. The acidification caused by positive diagnostic LAMP reactions was converted into a fluorescent signal by the optical pH sensors. Sensor precursor solution was drop-cast into the centrifugal microfluidics’ reaction chambers and using a custom-built imaging rig, allele-specific LAMP (AS-LAMP) and RT-LAMP assays could be performed for multiplexed discrimination of human CYP2C19 alleles and respiratory virus RNA, respectively. Assa

Micro-structured flow reactors have a great potential in chemical synthesis due to more efficient heat transfer, better control of mixing, higher yield of desired products, safety when handling reactions involving hazardous substances, and the possibility of automation. Oxygen and water are important analytes in the monitoring of chemical synthesis. They participate in a wide range of processes, which may be desirable or interfering. Among many small molecule sensing methods, the optical chemical sensors are a popular choice, as it features non-invasiveness, full reversibility, precise and accurate measurements, ease of miniaturization, and imaging of the analyte on various scales. However, most oxygen sensors cater to biological studies which emphasise only the physiological range of oxygen concentration and compatibility with biomolecules or cells. These sensors are often prone to leaching and even dissolution in organic solvents, limiting their use in chemical synthesis. Herein, two optical sensors, one dedicated to trace amounts of oxygen and one dedicated water in a chemical reaction are presented. The sensors were integrated into a microstructured flow reactor, and the sensors enabled real-time and spatially resolved monitoring of oxygen and water.

Digital microfluidics (DMF) is an emerging fluid-handling technology popular in chemical, biological, and biomedical applications due to its portability, automation, small reagent consumption, short analysis time, parallelization of different processes, and flexible device geometry. In this thesis, polydopamine (PDA) nanoparticles (NPs) synthesis was optimized on the DMF platform by adjusting the incubation time, reagent concentration, and molar ratio. The synthesis of monodispersed PDA NPs with a narrow size distribution was confirmed with SEM images. In addition, a new sandwich-structured PDA-silver hybrid material was designed and produced with a layer-by-layer assembly process named as PDA-Ag-PDA, where silver nanoparticles were wrapped between two layers of PDA, and the film was subsequently integrated with DMF. Each layer of PDA-Ag-PDA coating was analysed with 3D surface metrology, contact angle meter, and SEM-EDS, and AFM to measure their roughness values, water contact angle, element distribution, respectively. Silver is a common Surface Enhanced Raman Spectroscopy (SERS) material, and the enhancement factor of PDA-Ag-PDA was estimated to be 1.9 × 104 using Rhodamine 6G as a probe molecule. The antibacterial property assays were performed on DMF by real-time monitoring the oxygen consumption during E. coli growth; the microfluidic approach consumed a smaller volume of reagent, required a shorter analysis time (maximum 10 hours), and allowed parallel operations to be performed. The PDA-Ag-PDA film with low cytotoxicity and strong antimicrobial effect was successfully developed and integrated with DMF, which can be an alternative platform for conducting biological applications on DMF in the future, in particular, for the adhesive protein and cells analysis.

Significant advantages of microfluidics such as lower sample consumption and shorter reaction time make it become popular in chemical and biological analysis. Luminescence sensors are attractive to measure these parameters as they provide high sensitivity, non-invasive detection, and fast response. In this dissertation, luminescence sensors were integrated with different microfluidic systems to monitor the temperature or pH value during the analytical process. These systems were designed, proposed, and extensively discussed. Several integration methods have been explored that combines sensor probes and microfluidics as a detection scheme, which simplified the fabrication process and reduced the cost. The methods for temperature sensing, poly(styrene-co-acrylonitrile) and temperature probe tris(1,10-phenanthroline)ruthenium(II) was generated by blade coating on a glass substrate. This sensing layer was directly bound to PDMS with microfluidic channels which led to a microfluidic system that was feasible for temperature detection in the microchannel by imaging. In DNA melting curve analysis, the chips could be employed to generate and measure thermal gradients in the resolution of 0.13 ℃. Analysis of the fluorescence intensity of stained DNA through multispectral optical imaging illuminated by LED was done, giving the results for screening of the BRCA 2 breast cancer gene that enabled to discriminate two double-strand DNA even in 0.7 ºC difference. For pH sensing, the fluorescent pH probe fluorescein isothiocyanate was conjugated to fluorinated silica nanoparticles, which formed the droplets by Pickering emulsion. This conjugation led to stabilization of the emulsified droplets as well as capability of detecting the pH in the droplets. This pH sensor innovatively used in the microdroplet system could measure the pH of the extracellular microenvironment (pHe) of single-cell and provided support for the growth of cells in the droplets. The pHe show

A composite film material that combines CsPbBr3 perovskite nanocrystals with a Hyflon AD 60 fluoropolymer was developed and utilized for high-resolution optical temperature imaging. It exhibited bright luminescence and, most importantly, long-term stability in an aqueous medium. CsPbBr3 nanocrystal-Hyflon films immersed in aqueous solutions showed stable luminescence over at least 4 months and exhibited a fully reversible pronounced temperature sensitivity of 1.2% K-1 between 20 and 80 °C. They were incorporated into a digital microfluidic (electrowetting on dielectric) platform and were used for spatially resolved temperature measurements during droplet movements. Thermal mapping with a CsPbBr3 nanocrystal-Hyflon sensing layer in a room temperature environment (22.0 °C) revealed an increase in local temperatures of up to 40.2 °C upon voltage-driven droplet manipulations in a digital microfluidic system, corresponding to a local temperature change of up to 18.2 °C.