Fluorescent Substances Research Articles

A fluorescent biosensor based on surface cell imprinting film for Salmonella typhimurium detection

Salmonella typhimurium (S. typhimurium) is a major foodborne pathogen that poses a potentialrisk to public health. The development of biosensors that are specific, sensitive, and easy to manipulate can greatly reduce the potential risk posed by S. typhimurium. A robust, highly sensitive and specific fluorescent biosensor was proposed by combining N-succinyl-chitosan-doped surface bacterial cell imprinted film (SCIF) with typical aggregation induced emission (AIE) fluorescent substance Au(I)-disulfide nanoparticles. The proposed fluorescent sensor can achieve linear detection of S. typhimurium in the concentration range from 10 to 106 CFU/mL with a detection limit of 4 CFU/mL. In addition, the modification of the SCIF on the surface enables specific abiotic recognition of the target bacteria. This fluorescence sensing strategy can be used for the detection of S. typhimurium in chicken meat samples. The platform can be replicated for the detection of other bacteria or cells via making different SCIFs, which is promising for the detection of practical samples for clinical and biological applications.

Sustainable approach for landfill leachate treatment through dielectric barrier discharge/ferrate (DBD/Fe(VI)) enhanced nanofiltration

Landfill leachate, with its high concentrations of persistent organic pollutants, salts, heavy metals, and emerging contaminants, presents significant environmental challenges. This study investigated the combination of dielectric barrier discharge (DBD) and ferrate (Fe(VI)) pretreatment technology in landfill leachate treatment, focusing on its effectiveness in enhancing oxidation performance and mitigating membrane fouling. The results indicated that after DBD/Fe(VI) treatment, TOC and UV254 removal efficiencies increased by 44 % and 67 %, respectively. Additionally, the DBD/Fe(VI) system excelled in removing fluorescent substances and high molecular weight organic compounds, thereby reducing the formation of the cake layer on the nanofiltration membrane. This system enhanced oxidation performance through the synergistic production of reactive intermediates, with Fe(V)/Fe(IV) and •OH being the main active species, O2•-, and 1O2 also contributing significantly. The degradation pathway of perfluorooctanoic acid was investigated by utilizing it as the representative pollutant. Compared to the raw landfill leachate system, the DBD/Fe(VI) increased membrane flux by 104 %, while reducing reversible and irreversible fouling resistances by 67 % and 75 %, respectively. Furthermore, the advantages and practical application potential of the DBD/Fe(VI) system were evaluated from energy consumption, economic cost, and carbon dioxide emissions. The study offers an innovative method for landfill leachate treatment and fouling mitigation.

Dual-Mechanism Quenching Electrochemiluminescence System by Coupling Energy Transfer with Electron Transfer for Sensitive Competitive Aptamer-Based Detection of Furanyl Fentanyl in Food.

Resonance energy transfer (RET) quenching is significantly important for developing electrochemiluminescence (ECL) sensors, but RET platforms face challenges like interference from other fluorescent substances and reliance on energy transfer efficiency. This study used Zn-PTC, formed by zinc ions coordinated with perylene-3,4,9,10-tetracarboxylate, as a dual-mechanism quencher to reduce the ECL intensity of carbon nitride nanosheets (Tg-CNNSs). Co3O4/NiCo2O4 acts as a coreaction promoter, enhancing and stabilizing the luminescence of Tg-CNNSs. Zn-PTC absorbs energy from Tg-CNNSs, altering the fluorescence lifetime to confirm energy transfer, while energy-level matching demonstrates electron transfer. By leveraging both RET and electron transfer mechanisms, the designed ECL aptasensor significantly reduces signal fluctuations that may arise from a single mechanism, resulting in more stable and reliable detection outcomes. The ECL aptasensor designed for furanyl fentanyl (FUF) detection shows excellent performance with a detection limit of 5.7 × 10-15 g/L, offering new pathways for detecting FUF and other small molecules.

A ratiometric fluorescent biosensing platform based on CDs and AuNCs@CGO for patulin detection

BackgroundPatulin (PAT) is a mycotoxin, usually found in fruit and their products, that can potentially be harmful to human health. In order to achieve rapid detection of mycotoxins and ensure the safety of food. This study reported a novel ratiometric fluorescent aptasensor for PAT detection. In this study, we used aptamer as the recognition element, Hybrid double stranded modified with fluorescent substances as the fluorescent donor, and AuNCs@CGO as the fluorescent acceptor. After the addition of PAT, the ratiometric fluorescence “turn on” response was exhibited. ResultsThe AuNCs@CGO are obtained by amide reaction between BSA-AuNCs and carboxylated graphene oxide (CGO). The prepared AuNCs@CGO can shorten the time of FRET effect and exhibit highly efficient quenching ability by adsorption effects (π-π stacking and electrostatic gravity) on the Aptamer-modified CDs. When the target PAT bound specifically to the CDs-apt, the fluorescence of the CDs-apt would recover, while the fluorescence of ROX modified cDNA remained unchanged. This ratiometric fluorescence response improved the accuracy of PAT detection. In addition, the proposed had good linearity for PAT in the range of 0.1–50 ng/mL with a limit of detection 0.16 ng/mL. The recovery of standard addition in grapes were 95.9%–105.4 %. SignificanceAn effective fluorescent detection method for PAT was constructed based on aptamer and nanomaterials. This new fluorescent biosensor has the characteristics of simple synthesis, easy operation, high sensitivity, strong selectivity and a low LOD, which may be a promising idea and platform for the detection of food safety hazard factors.

Determination of 4-n-butylresorcinol by fluorescence derivatization based on dopamine

4-n-butylresorcinol (4nBR) is a frequently utilized as whitening ingredients in skincare cosmetics. Compared with other whitening ingredients, it can effectively inhibit tyrosinase with lower toxicity and superior inhibition efficacy. Under alkaline conditions, an induced oxidative coupling reaction can occur between 4nBR and dopamine (DA) to generate strong fluorescent substance azamonardine with an intense emission band centering at 476 nm when excited at 440 nm. This phenomenon can be used to establish a fluorescence analysis method for 4nBR. The results indicated that the linear range of the method was 1.0–24.0 nmol L−1, and the detection limit was as low as 0.25 nmol L−1. The method showed high sensitivity, good selectivity, mild experimental conditions and low cost. The proposed method was successfully used to detect 4nBR in cosmetics, and the results were consistent with those of HPLC. The spiking recoveries were between 98.2% and 108 %.

Research on the removal efficiency and membrane fouling analysis of nanofiltration membranes under the combined pollution of emerging contaminants

Based on the research background of five emerging contaminants (ECs)— sulfadiazine (SD), sulfamethoxazole (SMZ), malathion, hexachlorobenzene (HCB), and bisphenol A (BPA)—which can be detected in trace amounts in a river basin in southern China, a spiking experiment was conducted to effectively address the potential impact risks of these contaminants. The experiment aimed to investigate the removal efficiency and membrane fouling of nanofiltration membranes (NF) under the combined pollution of these ECs. The experimental results show that under the combined pollution of these ECs, the NF exhibits good removal efficiency for all five ECs, with removal rates of approximately 83 ± 2 %, 84 ± 3 %, 76 ± 3 %, 73 ± 6 %, and 80 ± 5 % for SD, SMZ, malathion, HCB, and BPA, respectively. Additionally, NF also has high efficiency in removing other pollutants, with removal rates for chromaticity, CODMn, and total hardness at 80 ± 2 %, 60 ± 3 %, and 62 ± 2 %, respectively, and over 80 % of fluorescent substances were removed. Analysis of the key operating indicators of the NF under the combined pollution of ECs revealed that the membrane flux decreased slightly faster compared to without the combined pollution of ECs, and both the membrane fouling index and membrane resistance increased to a certain extent. Furthermore, the analysis of the NF chemical cleaning solutions showed that these ECs can be detected in both alkaline and acid cleaning solutions. Analysis of membrane dissection on NF revealed that severe cake layer contamination formed on the membrane surface both under and without the combined pollution of ECs, the presence of ECs is worse than the absence of ECs.

Signal-amplified detection of amyloid-β aggregates based on plasmon-enhanced fluorescence

Protein aggregation and misfolding are the main causes of neurodegenerative diseases. The development of a sensitive detection method and early diagnosis is significant for the prevention, diagnosis and treatment of these diseases. Herein, boron dipyrromethene (BODIPY)-modified probe based on plasmon-enhanced fluorescence (PEF) was developed for the detection of amyloid-β protein (Aβ) aggregates. Gold nanoparticles (Au NPs) and BODIPY were as the plasma, fluorescent substance, respectively. Meanwhile, the distance between the Au NPs and the BODIPY was controlled by silica spacer. Compared with the original BODIPY, the fluorescence signal of BODIPY-decorated Au NPs (Au NPs@SiO2-BODIPY) exhibited 13-fold fluorescence enhancement. Three dimensions finite difference time domain (3D-FDTD) result demonstrated the signal-amplified was ascribed to the increase of electric field intensity (3.78 V/m). The linear range and detection limit for Aβ42 detection were lowered to 5–60 μM and 0.85 μM. The developed PEF probe was applied to selective and sensitive recognize Aβ aggregates in mouse colorectal carcinoma cells (CT26) and mouse pancreatic cancer cells (PAN02), which also showed a higher fluorescent signal than the original BODIPY. This method has a broad application prospect in the prediction and detection of neurodegenerative diseases.

Dielectric Barrier Discharge (DBD) enhanced Fenton process for landfill leachate nanofiltration: Organic matter removal and membrane fouling alleviation

This study investigated a sustainable approach through dielectric barrier discharge (DBD) enhanced Fenton technology coupling nanofiltration (NF) process for landfill leachate treatment. The DBD/Fe(II)/H2O2 system exhibited significant synergistic effects, removing 55.07 % of TOC and 53.79 % of UV254 within 60 min, respectively. Additionally, the DBD/Fe(II)/H2O2 system demonstrated exceptional performance in removing fluorescent substances and large molecular organic compounds, thereby reducing the formation of cake layer on the nanofiltration membrane. Moreover, membrane flux increased by 2.34 times, with reversible and irreversible resistances decreasing by 75.79 % and 81.55 %, respectively. Quenching experiments revealed ·OH as the primary active species for perfluorooctanoic acid (PFOA) degradation in the DBD/Fe(II)/H2O2 process. The degradation pathway of PFOA was also elucidated via capillary electrophoresis-quadrupole time-of-flight mass spectrometry analysis. Correlation analysis indicated that TOC and EEM were the primary fouling factors. Lastly, through an assessment of energy consumption, economic costs, and carbon dioxide emissions, the advantages and practical application potential of the DBD/Fe(II)/H2O2 system were demonstrated. In summary, the DBD/Fe(II)/H2O2 system emerges as a feasible strategy for NF pretreatment, holding immense potential for treating landfill leachate.

A novel-approach for identifying sources of fluvial DOM using fluorescence spectroscopy and machine learning model

Rivers are well known as one of the most threatened aquatic environments, whose structure and water quality can be deeply impacted by intensive anthropogenic activities. Despite the fact that anthropogenic influences on river ecosystems could indeed be deduced from the composition and chemistry of fluvial dissolved organic matter (DOM), sources of anthropogenic loading to DOM are still poorly explored. Here, by uniting fluorescence excitation-emission matrices (EEM) and principal component absolute coefficient, four sources of DOM from seventeen rivers in major drainage basins of China could be identified, i.e., originating from municipal sewage, domestic wastewater, livestock wastewater, and natural origins, and thus being defined as MS-DOM, DW-DOM, LW-DOM, NO-DOM, respectively. Based on the random forest model, special nodes in EEM could be traced from four sources, respectively. According to parallel factor analysis, DOM mainly contained protein-like, microbial humic-like, and fulvic-like fluorescence substances, among which protein-like was dominant in MS-DOM and DW-DOM, microbial humic-like in LW-DOM, and fulvic-like in NO-DOM. Based on key peaks and essential nodes in EEM, the identifying source indices were first proposed, which could be introduced to simply distinguish the different anthropogenic-derived sources of fluvial DOM. It was associated with intensity ratios of the key peaks and the essential nodes of EEM spectra from four sources, i.e., municipal sewage (MS-SI: Ex/Em = 280/(335, 410) nm), domestic wastewater (DW-SI: Ex/Em = 280/(340, 410) nm), livestock wastewater (LW-SI: Ex/Em = 235/(345, 380) nm), and natural origins (NO-SI: Ex/Em = 260/(380, 430) nm). By statistical analysis, the high identifying source indices of municipal sewage (>0.5) and natural origins (>0.4) values could be related to MS-DOM and NO-DOM, respectively. The identifying source indices of domestic wastewater with 0.1–0.3 might be linked to DW-DOM and the identifying source indices of livestock wastewater with 0.3–0.4 to LW-DOM. Compared with conventional optical indices, the novel identifying source indices showed remarkable discrimination for the sources of fluvial DOM with different forms of anthropogenic disturbances. Hence the innovative approach could be relatively convenient and accurate to evaluate water quality or pollution risk in river ecosystems.

Disinfection-residual bacteria (DRB) after chlorine dioxide treatment: Microbial community structure, regrowth potential, and secretion characteristics

This study investigates the effects of chlorine dioxide (ClO2) disinfection on the community structure, regrowth potential, and metabolic product secretion of disinfection-residual bacteria (DRB) in secondary effluent (SE), denitrification filter effluent (DFE), and ultrafiltration effluent (UE). Results show that ClO2 effectively reduces bacteria in SE and UE, achieving log removal values exceeding 3 at 1 mg/L within 30 min. A salient positive correlation (R2 > 0.95) exists between changes in total fluorescence intensity and disinfection efficacy. Post-treatment, Acinetobacter abundance increased in SE, while Pseudomonas decreased in DFE and UE. At lower ClO2 concentrations, Staphylococcus, Mycobacterium, Aeromonas, and Lactobacillus increased in DFE, but decreased at higher concentrations. After storage, bacterial counts in disinfected samples exceeded those in the control group, surpassing 105 CFU/mL. Despite an initial decline, species richness and evenness partially recovered but remained lower than control levels. Culturing DRB for 72 h showed elevated extracellular polymeric substances (EPS) secretion, quantified as total organic carbon (TOC), ranging from 5 to 27 mg/L, with significantly higher EPS in the disinfection group. Parallel factor analysis with self-organizing maps (PARAFAC-SOM) effectively differentiated water sample types and EPS fluorescent substances, underscoring the potential of three-dimensional fluorescence as an indirect measure of ClO2 disinfection efficacy.

O-229 Neck scarf of ureter and Intraoperative ICG-fluorescence for preventing ureters injuries in Da Vinci Robotic deep infiltrating endometriosis excision

Abstract Study question To prevent ureters injury during deep infiltrating endometriosis excision. Summary answer Identify the ureter course with ICG and near-infrared fluorescence (NIRF) imaging mode and traction with a vessel loop like neck scarf in white light mode. What is known already Deep infiltrating endometriosis is one of the most challenging gynecologic operation due to the distorted anatomy by the fibrosis of endometriosis gland.Identification of ureters through intraurethral ICG instillation and NIRF imaging has been reported to be useful during robotic surgery. However, surgeons cannot do robotic ureterolysis in Firefly NIRF imaging mode. When shift back to the white light mode, surgeons could only try to remember the ureter course during the ureterolysis procedure.When the ureter course was in doubt, the surgeon must shift back to the ICG-NIRF image mode again. Study design, size, duration From 2017 Jan1 till 2024 Jan 7, a single surgeon perform 47 consecutive patients with DIE received robotic surgery with ureterolysis from pelvic brim to the level of uterine vessels crossing them. Yellow and blue rubber bands were used to collar the ureters as a neck scarf, with Da Vinci robot system (SI, XI)The third arm as an stable assistant to traction the neck scarf to traction ureter indirectly in different direction when ureterolysis. Participants/materials, setting, methods We perform cystoscopy and intraurethral ICG injection with or without ureteral stent placement and Inject ICG-fluorescence with Firefly fluorescence imaging if the ureters were hard to find due to adhesion and fibrosis. Under the Firefly NIRF imaging mode,the location of ureter over the pelvic brim was found and the vessel loops were set up. Then shift back to white light mode to do the ureterolysis. Main results and the role of chance 47 consecutive patients with deep infiltrating endometriosis were safely operated without fistula, ureter injury, laceration during one month to 5 years period follow up. In them 2 patients need cystoscopy and ICG-NIRF help to setting up the vessel’s loops. Conclusion The surgeons could always keep the ureter safety during difficult endometriosis dissection with the vessel loops over the ureter as a neck scarf.There will be an indirect traction force pulled by robotic assistant forceps in the regular robotic laparoscopy light source mode during ureterolysis. The Firefly NIRF imaging mode could be used to help in setting up the neck scarf of ureters when the adhesion and fibroisis made the ureters course obscure. Limitations, reasons for caution Indocyanine Green is a fluorescent substance visible in near-infrared light. It is FDA-approved with IV injection for the identification of anatomical structures.The intra-ureteral ICG injection is off-label use. Wider implications of the findings Our techniques could be applied to all pelvic surgeries especially DIE, broad ligament and cervix myoma, scar defect repair and gynecologic cancer surgery, to preventing the ureters injured. However, further studies will be warranted. Trial registration number non-clinical trials

Sensitive and High-Throughput Time-Resolved Luminescence Detection of Tetracycline in Milk for Eliminating Background Fluorescence on a Miniaturized Apparatus.

Fluorescence detection has always suffered from high background fluorescence from real samples such as milk. Therefore, cumbersome pretreatments of samples were necessary to remove the fluorescent substances but led to long processing times and low efficiency. Time-resolved luminescence detection is a powerful technique for eliminating short-lived background fluorescence without additional pretreatments. However, the related instruments are usually equipped with high-speed excitation sources and detectors, which are always bulky and expensive. Herein, we developed a low-cost and miniaturized imaging system for high-throughput time-gated luminescence detection. An UV LED array was used to excite multiple samples, the luminescence of which could be detected by a smartphone simultaneously. An analog circuit was designed to synchronize the LED to the mechanical chopper to eliminate the background signals resulting from scattering and short-lived autofluorescence. Compared to other synchronous circuits based on FPGAs and microcontrollers, this analog circuit required no programming and memory. For the first time, high-throughput time-resolved luminescence detection of tetracycline in milk without any separation or enrichment was achieved by utilizing a smartphone as a camera, and the scattered signals and the background fluorescence were eliminated efficiently. The limit of detection reached as low as 53 nM (∼0.024 ppm), lower than the residue limit set by the European Union. This high-throughput time-gated luminescence detection method can be used for quantitative analysis of many real samples with high background fluorescence.

Comparison of chlorine and peroxymonosulfate in enhancing vacuum ultraviolet for treating secondary effluent to mitigate ultrafiltration membrane fouling

Herein, sodium hypochlorite (NaClO) and peroxomonosulfate (PMS) were systematically compared in enhancing vacuum ultraviolet (VUV) oxidation for alleviating ultrafiltration membrane fouling of effluent organic matter. Results indicated that VUV/NaClO pre-treatment exhibited significantly better performance than VUV/PMS, with the irreversible fouling resistance reduced by 64 %. Simultaneously, 96 % of fluorescent substances were removed by VUV/NaClO, and an apparent decrease in surface deposits was observed, with membrane pores exposed and clearly visible. The calculation results through the extended Derjaguin-Landau-Verwey-Overbeek theory indicated that the enhanced hydrophilicity of pollutants reduced the tendency of pollutants to adhere to the membrane surface, leading to the weakening of membrane fouling degree. In the VUV/PMS process, HO• and SO4•– were detected with steady-state concentrations of 8.55 × 10-14 and 1.53 × 10-13 M. By contrast, the VUV/NaClO system generated HO•, Cl•, ClO•, and Cl2•– with steady-state concentrations of 1.15 × 10-13, 8.79 × 10-14, 7.30 × 10-13 and 1.50 × 10-13 M. In conclusion, VUV/NaClO pre-treatment demonstrated high efficiency and significant potential in improving water quality and decreasing membrane fouling in secondary effluent treatment.

Determination of glucose oxidase activity by tyrosine fluorescence spectrophotometry

A novel Fe2+/Tyr/H2O2 fluorescence reaction system has been established for the purpose of analyzing glucose oxidase activity. This system involves the catalysis of glucose oxidase on glucose to produce H2O2, which in turn oxidizes tyrosine to a highly fluorescent substance under the catalysis of Fe2+. The fluorescence intensity is subsequently employed to ascertain the enzymatic activity of glucose oxidase. The enzymatic oxidation reaction and tyrosine fluorescence reaction conditions were optimized based on the H2O2 standard curve equation. Direct fluorescence spectrophotometry was used to determine the activity range and detection limit of glucose oxidase, which were found to be 7.00 × 10−5–7.00 × 10−2 U/mL and 3.36 × 10−5 U/mL (Enzyme-like activity is 6.72 × 10−4 U/mL, The enzyme reaction time is 5 min), respectively, with a relative standard deviation of less than 3.2 %. This method has been successfully applied to determine the activity of glucose oxidase in food additives, with a recovery rate ranging from 96.00 % to 102.0 %.

Enhanced removing of cyanobacterium by NZVI coupled with H2O2: Influencing factors and removal mechanisms

AbstractAs advanced oxidation processes (AOPs) is considered to be a highly effective approach for degrading organic pollutants, the simultaneous coagulation and oxidation process by the Fenton‐like reaction of nanoscale zero‐valent iron (NZVI) and hydrogen peroxide (H2O2) is investigated to eliminate the harmful cyanobacterium Microcystis aeruginosa in this study, and the process conditions are optimized using the central composite design of response surface methodology (RSM); in addition, the removal efficiency of M. aeruginosa (in terms of chlorophyll a, Chl a) and the verifications of the antioxidant abilities, as well as extracellular organic matters (EOM) and intracellular organic matters (IOM) are investigated under the optimized conditions. Results indicate that H2O2 concentration is the key factor affecting the Chl a removal efficiency, and the maximum Chl a removal reaches 98.10% under the optimized conditions: NZVI concentration 62.82 mg L−1, H2O2 concentration 54.2 mmol L−1, pH 4.38 and rotating speed 67 rpm. The high correlation coefficient (R2 > 0.80) of analysis of variance (ANOVA) demonstrates the RSM model is extremely significant and suitable for experimental results. Moreover, the total organic carbon (TOC) and fluorescent substances (soluble cyanobacteria metabolic byproducts, aromatic proteins II, humic and fulvic acid‐like compounds) for both EOM and IOM are enhanced removal. It is speculated the removal mechanisms of the Fenton‐like process of NZVI/H2O2 for cyanobacterium belongs to the combined actions of the oxidation of Fe(II)/H2O2 and the coagulation of Fe(III), which destroy the defense system and result in the removal of M. aeruginosa.

Effects of calcined oyster shell powder composited with iron salt on the simultaneous removal of phosphorus and arsenic during algal bloom control process

Calcined oyster shell powder (COS) has the potential to serve as an efficient coagulant aid in water treatment for iron salt (IS) due to its potentially high aid capacity in alkalinity recovery and the simultaneous removal effects on algae, arsenic, phosphorus, and organic substances. However, little information is available on the specific effects and environmental impacts of COS composited with IS in coagulation for algal bloom removal. Hence, the COS was used as a coagulant aid to investigate the simultaneous removal effects on phosphorus and arsenic as well as the water environment changes during the bloom control of Microcystis aeruginosa using ferric chloride as a coagulant impacted by different hydraulic disturbances. Results showed that compared to the single IS coagulation with a pH value of about 3.1, the pH value significantly increased and stabilized at 7.5 from the 3rd day with the COS as the coagulant aid condition. Meanwhile, the removal rates of arsenic and phosphorus also improved by 14.4 % and 50.6 %, respectively, within 12 h, achieving near complete removal with little re-release risk, demonstrating excellent alkalinity adjustment and persistently simultaneous removal effects on phosphorus and arsenic. Furthermore, the coagulation aid of COS effectively inhibited the release of fulvic acid-like substances from algal cells on the 7th day. Meanwhile, it promoted the secretion of humic acid-like substances and microcystins production, as well as the release of fluorescent substances under hydraulic disturbance conditions. From the structural information presented by X-ray photoelectron spectroscopy (XPS), the precipitates mainly consisted of proteins and lipids derived from algal cells, calcium carbonate, ferric hydroxide, and trace amounts of arsenite, further confirming their precipitated mechanism of algal cell combined through COS and IS. The results provide scientific support for the practical application of COS in algal blooms and its subsequent environmental risk control.

Fiber optic-based integrated system for in vivo multiscale pharmacokinetic monitoring.

This paper presents the development of a fiber-optic-based fluorescence detection system for multi-scale monitoring of drug distribution in living animals. The integrated system utilized dual laser sources at the wavelengths of 488 nm and 650 nm and three photomultiplier channels for multi-color fluorescence detection. The emission spectra of fluorescent substances were tracked using the time-resolved fluorescence spectroscopy module to continuously monitor their blood kinetics. The fiber bundle, consisting of 30,000 optic filaments, was designed for wide-field mesoscopic imaging of the drug's interactions within organs. The inclusion of a gradient refractive index (GRIN) lens within the setup enabled fluorescence confocal laser scanning microscopy to visualize the drug distribution at the cellular level. The system performance was verified by imaging hepatic and renal tissues in mice using cadmium telluride quantum dots (CdTe QDs) and R3. By acquiring multi-level images and real-time data, our integrated system underscores its potential as a potent tool for drug assessment, specifically within the realms of pharmacokinetic and pharmacodynamic investigations.

A novel red fluorescent and dynamic nanocomposite hydrogel based on chitosan and alginate doped with inclusion complex of carbon dots

Red fluorescent hydrogels possessing injectable and self-healing properties have widespread potential in biomedical field. It is still a challenge to achieve a biomacromolecules based dynamic hydrogels simultaneously combining with excellent red fluorescence, good mechanical properties, and biocompatibility. Here we first explore hydrophilic inclusion complex of (R-CDs@α-CD) derived from hydrophobic red fluorescent carbon dots (R-CDs) and α-cyclodextrin (α-CD), and then achieved a red fluorescent and dynamic polysaccharide R-CDs@α-CD/CEC-l-OSA hydrogel. The nanocomposite hydrogel can be fabricated through controlled doping of red fluorescent R-CDs@α-CD into dynamic polymer networks, taking reversibly crosslinked N-carboxyethyl chitosan (CEC) and oxidized sodium alginate (OSA) as an example. The versatile red fluorescent hydrogel simultaneously combines the features of injection, biocompatibility, and augmented mechanical properties and self-healing behavior, especially in rapid self-recovery even after integration. The R-CDs@α-CD uniformly dispersed into dynamic hydrogel played the role of killing two birds with one stone, that is, endowing red emission of a hydrophilic fluorescent substance, and improving mechanical and self-healing properties as a dynamic nano-crosslinker, via forming hydrogen bonds as reversible crosslinkings. The novel red fluorescent and dynamic hydrogel based on polysaccharides is promising for using as biomaterials in biomedical field.

High-throughput fluorescence quantification method based on inner filter effect and fluorescence imaging analysis

The application of the inner filter effect (IFE) in fluorescent substance determination is gaining popularity. In this paper, a theory of the fluorescence distribution along with the excitation light path is derived from our previous research about the spatial micro-element method. According to the relationship between the summation of fluorescence intensities along the vertical direction at a certain position on the excitation light path and the position, a high-concentration and wide-range fluorescent substance quantification method based on the IFE and fluorescence imaging analysis is proposed. Correspondingly, a high-throughput fluorescent substance quantification detection system is constructed. In order to validate the method, solutions of rhodamine B in different concentrations are used for principle validation, concentration prediction, and experimental investigation on the influence of integration time and lens distortion. The high-throughput system enables the simultaneous measurement of six samples, realizing the high-concentration and wide-range quantification of rhodamine B (100–600 mg/L) with high precision (R2 = 0.9992, MRE = 2.34 %). By setting the filter wheel, the system can measure the concentration of fluorescent substances with different emission wavelengths. The improvement of experimental device is expected to reduce the single sample capacity to tens of microliters and increase the overall sample quantity to tens or even hundreds. The proposed method and system are beneficial to fluorescence measurement in fields such as biomedicine and dye research and to the improvement of high-throughput fluorescence quantitative PCR instruments.

Long-term pilot study on advanced treatment of lake water by ultrafiltration / nanofiltration

Advanced water treatment technologies, including ozone biologically activated carbon adsorption (O3-BAC), ultrafiltration (UF), and nanofiltration (NF), are essential for enhancing drinking water quality. O3-BAC and UF excel in pathogen, virus, and by-product removal, while NF promises enhanced contaminant elimination for high-quality water. However, the implementation of combined UF/NF dual-membrane treatment processes in large-scale water treatment facilities using surface water sources like lakes remains relatively novel. The lack of long-term operational data is the main reason for the limited widespread adoption. To address this, two pilot systems were established: one comprising ‘O3-BAC + pressure-driven UF(I) + NF(I) (Route 1 at 6.4m3/h)’, and the other ‘immersed UF(II) + NF(II) (Route 2 at 3.2m3/h)’, undergoing a year-long evaluation. The trials showed that the dual-membrane systems were effective and resistant to interference. Notably, they achieved removal efficiencies exceeding 98 % for turbidity, UV254 absorbance, fluorescence substances, and algae, alongside significant reductions in odor (80 %) and total dissolved solids (TDS) by 30 %. Both membrane systems display promising performance and O3-BAC is recommended as a pretreatment process. Analysis revealed that the primary constituents of membrane fouling on the NF membranes are aluminum silicate, SiO2, CaCO3 particles, and organic pollutants, which are typically formed through interactions between calcium ions and dissolved organic matter (DOM). The most effective cleaning protocol involves acidic-alkaline treatments. This study provides valuable operational insights into advanced treatment processes using dual-membrane combinations for water treatment plants that rely on lake water sources.