Quantitative analysis of microplastics and nanoplastics released from disposable PVC infusion tubes

The exposure of micro- and nanoplastics (MNPs) via medical device is still unknown to us. Herein, a visual quantitative detection of polyvinyl chloride (PVC) MPs and a fluorescent quantitative detection of PVC NPs were developed. To overcome the aggregation of PVC NPs, sodium dodecylbenzene sulfonate was used as the stabilizer of PVC NPs. The brand-new disposable PVC infusion tubes were found to carry PVC MPs with the average total number (ATN) of 931.4 particles and PVC NPs with the average mass of 0.040 μg, respectively. For four typical infusion fluids such as 0.9% sodium chloride, 5% glucose, 5% sodium bicarbonate, hydroxyethyl starch 40 sodium chloride, the released PVC MPs and NPs were ranged from 1003.6 ∼ 3494.6 particles and 0.042 ∼ 0.087 μg, respectively in stimulating normal infusion scenario (room temperature 4 h). The released PVC MPs and NPs were also increased with the infusion duration and temperature. The released PVC MPs are mainly in granular form, accounting for 38 ∼ 49% of the total PVC MPs. Our findings indicate PVC MNPs can enter the blood vessel directly with the infusion fluids during intravenous infusion and the PVC MNPs exposure risk towards patients deserves more attention.

Enzyme-assisted amplification of target cycle triggers the unlocking of locked hairpin probes for let-7a detection

The detection of miRNA in cells is difficult owing to its substantially low cellular content. Therefore, developing a highly sensitive sensor to detect cellular miRNA remains a significant challenge. Herein, we report an enzyme-assisted biosensor with target cycle amplification that can trigger the unlocking of locked hairpin probes for sensitive and robust let-7a gene detection. In the research, three kinds of hairpin probes were skillfully designed. The hairpin probe comprises a complementary sequence of a target, primer, and recognition site of Nt. BbvCI restriction endonucleases. In addition, the alternating synergistic impact of polymerase and the nicking enzyme generates considerable triggers to unlock the locked hairpin probe LH1, consequently triggering a subsequent circulating strand displacement reaction to form a stable H1-H2 double strand to ensure sufficient distance between a fluorophore on H1 and a quenching group on bolt DNA (bDNA), and resulting in the recovery of fluorescence. Furthermore, this process does not require complicated operation procedures and instruments, and the target gene let-7a can be sensitively detected. Specifically, the detection limit of the biosensor is as low as 160 fM, and its linear range is 0.5 pM-250 nM. Moreover, this biosensor can be employed to detect let-7a in human serum with good selectivity.

Rolling circle transcription and CRISPR/Cas12a-assisted versatile bicyclic cascade amplification assay for sensitive uracil-DNA glycosylase detection

Uracil-DNA glycosylase (UDG) is pivotal in maintaining genome integrity and aberrant expressed UDG is highly relevant to numerous diseases. Sensitive and accurate detecting UDG is critically significant for early clinical diagnosis. In this research, we demonstrated a sensitive UDG fluorescent assay based on rolling circle transcription (RCT)/CRISPR/Cas12a-assisted bicyclic cascade amplification strategy. Target UDG catalyzed to remove uracil base of DNA dumbbell-shape substrate probe (Sub_UDG) to produce an apurinic/apyrimidinic (AP) site, at which Sub_UDG was cleaved by apurinic/apyrimidinic endonuclease (APE1) subsequently. The exposed 5'-PO₄ was ligated with the free 3'-OH terminus to form an enclosed DNA dumbbell-shape substrate probe (E-Sub_UDG). E-Sub_UDG functioned as a template can actuate T7 RNA polymerase-mediated RCT signal amplification, generating multitudes of crRNA repeats. The resultant Cas12a/crRNA/activator ternary complex activated the activity of Cas12a, causing a significantly enhanced fluorescence output. In this bicyclic cascade strategy, target UDG was amplified via RCT and CRISPR/Cas12a, and the whole reaction was completed without complex procedures. This method enabled sensitive and specific monitor UDG down to 0.0005 U/mL, screen corresponding inhibitors, and analyze endogenous UDG in A549 cells at single-cell level. Importantly, this assay can be extended to analyze other DNA glycosylase (hAAG and Fpg) by altering the recognition site in DNA substrates probe rationally, thereby offering a potent tool for DNA glycosylase-associated clinical diagnosis and biomedical research.

A red-emitting Europium(III) complex as a luminescent probe with large Stokes shift for the sequential determination of Cu2+ and biothiols in real samples

In this work, a novel Eu³⁺-DTPA-bis(AMC) complex with red luminescence was designed and synthesized for sequential detection of Cu²⁺ and biothiols (Cys/Hcy/GSH) based on the displacement strategy with the good selectivity, high sensitivity, and large Stokes shift (288 nm). The possible detection mechanism was verified by UV-vis, the high-resolution mass spectrometry, and the fluorescence decay curve. The experimental parameters, including the solution pH, the incubation time, the concentration ratio of Eu³⁺-DTPA-bis(AMC) to Cu²⁺ and biothiols concentration, were optimized. Under the optimal conditions, it shows a good linear relationship between the concentration (0-10 μM) of Cu²⁺ and the fluorescence intensity of Eu³⁺-DTPA-bis(AMC), with a low detection limit of 0.065 μM. The linear range and the limit of detection of the Eu³⁺-DTPA-bis(AMC)/Cu²⁺ system for Cys/Hcy/GSH were 2.5-22.5/5-45/5-50 μM and 0.11/0.07/0.05 μM, respectively. Surprisingly, the high or low concentration of Eu³⁺-DTPA-bis(AMC)/Cu²⁺ can significantly affect the selectivity of the sensing system to biothiols (Cys/GSH/Hcy). When the concentration of the Eu³⁺-DTPA-bis(AMC)/Cu²⁺ system is 10.0 μΜ, it could recognize biothiols (Cys/GSH/Hcy) from other substances, but when the concentration is as low as 3.3 μM, it could further specifically distinguished Cys from Hcy/GSH. Owing to the high anti-interference characteristics, accuracy and specificity, the sensing system was well applied to the cascade detection of Cu²⁺ in actual environmental samples and Cys in biological and food samples, including FBS, urine, milk, beverage, fresh juice with the satisfactory recoveries from 96.20 to 106.80 %.

[Feasibility Investigation of Fluorescence Method in Uniport Thoracoscopic Anatomical Segmentectomy for Identifying the Intersegmental Boundary Line]

BACKGROUND

Segmentectomy has gradually become one of the standard surgical methods for small pulmonary nodules with early lung cancer on imaging. This study aimed to investigate the perioperative outcomes of patients who underwent uniport video-assisted thoracoscopic surgery (VATS) segmentectomy for identifying the intersegmental boundary line (IBL) by the near-infrared fluorescence imaging with intravenous indocyanine green (ICG) method or the modified inflation-deflation (MID) method and assess the feasibility and effectiveness of the ICG fluorescence (ICGF)-based method.

METHODS

We retrospectively analyzed the perioperative data in total 198 consecutive patients who underwent uniport VATS segmentectomy between February 2018 and August 2020. With the guidance of preoperative intelligent/interactive qualitative and quantitative analysis-three dimensional (IQQA-3D), the targeted segment structures could be precisely identified and dissected, and then the IBL was confirmed by ICGF-based method or MID method. Clinical effectiveness and postoperative complications of the two methods were evaluated.

RESULTS

An IBL was visible in 98% of patients by the ICGF-based group, even with the low-doses of ICG. The ICGF-based group was significantly associated with the shorter IBL clear presentation time [(23.59±4.47) s vs (1,026.80±318.34) s] (P<0.01) and operative time [(89.3±31.6) min vs (112.9±33.3) min] (P<0.01), compared to the MID group. The incidence of postoperative prolonged air leaks was higher in the MID group than in the ICGF-based group (8.0% vs 26.5%, P=0.025). There were no significant differences in bleeding volume, chest tube duration, postoperative hospital stays, surgical margin width and other postoperative complications (P>0.05).

CONCLUSIONS

The ICGF-based method could highly accurately identify the IBL and make anatomical segmentectomy easier and faster, and therefore has the potential to be a feasible and effective technique to facilitate the quality of uniport VATS segmentectomy.

Molecular structure and evolution characteristics of dissolved organic matter in groundwater near landfill: Implications of the identification of leachate leakage

Landfills can cause groundwater contamination, the pollution characteristics in groundwater near landfill sites have been extensively investigated, while the rapid identification of leachate leakage remained unclear. Comprehensively characterizing dissolved organic matter (DOM) is crucial for tracing the source, species, and migration of contaminants within groundwater and protecting groundwater sources. Here, we showed that DOM composition from newer landfills was mainly composed of newly-produced tryptophan and tyrosine, and protein-like and humic-like substances were more abundant in landfills that were relatively older. DOM in landfill groundwater was initially dominated by outputs from microbial activities, followed by terrigenous input. Leaked leachate contained an additional dye-derived fluorescent matter at the excitation/emission wavelength of 240-260/440-460 nm that was absent in uncontaminated groundwater. Leachate leakage increased the concentrations of humic-like substance, DOM molecular weight, and microbial activity in the downstream groundwater, resulting in the microorganisms rapidly multiply and secrete large amounts of microbial metabolism by-products, making them suitable indicators of groundwater pollution. Three criteria were proposed to establish an interpretable fluorescence method to identify leachate pollution. The obtained results provide a novel insight into not only the monitoring, early warning, and identification but also the transport, fate and removal or transformation of groundwater leachate in landfills.

A highly sensitive method for simultaneous detection of hAAG and UDG activity based on multifunctional dsDNA probes mediated exponential rolling circle amplification

DNA glycosylase is an indispensable DNA damage repair enzyme which can recognize and excise the damaged bases in the DNA base excision-repair pathway. The dysregulation of DNA glycosylase activity will give rise to the dysfunction of base excision-repair and lead to abnormalities and diseases. The simultaneous detection of multiple DNA glycosylases can help to fully understand the normal physiological functions of cells, and determine whether the cells are abnormal in pre-disease. Regrettably, the synchronous detection of functionally similar DNA glycosylases is a great challenge. Herein, we developed a multifunctional dsDNA probe mediated exponential rolling circle amplification (E-RCA) method for the simultaneously sensitive detection of human alkyladenine DNA glycosylase (hAAG) and uracil-DNA glycosylase (UDG). The multifunctional dsDNA probe contains the hypoxanthine sites and the uracil sites which can be recognized by hAAG and UDG respectively to generate apyrimidinic (AP) sites in the dsDNA probe. Then the AP sites will be recognized and cut by endonuclease Ⅳ (Endo IV) to release corresponding single-stranded primer probes. Subsequently, two padlock DNA templates are added to initiate E-RCA to generate multitudinous G-quadruplexes and/or double-stranded dumbbell lock structures, which can combine N-methyl mesoporphyrin IX (NMM) and SYBR Green Ⅰ (SGI) for the generation of respective fluorescent signals. The detection limits are obtained as low as 0.0002 U mL^-1 and 0.00001 U mL^-1 for hAAG and UDG, respectively. Notably, this method can realize the simultaneous detection of two DNA glycosylases without the use of specially labeled probes. Finally, this method is successfully applied to detect hAAG and UDG activities in the lysates of HeLa cells and Endo1617 cells at single-cell level, and to detect the inhibitors of DNA glycosylases.

Concentration-dependent photoluminescence carbon dots for visual recognition and detection of three tetracyclines

Concentration-dependent photoluminescence carbon dots (CDs) have been successfully synthesized through the one-step hydrothermal treatment of o-phthalic acid and ethylenediamine. The CDs possessed higher fluorescence quantum yield, up to 39.22%, exhibiting distinguished optical property, water solubility, and stability. The CDs that emit strong blue-green fluorescence can visually identify and determine tetracycline (TC), oxytetracycline (OTC), and chlortetracycline (CTC). TC quenched the fluorescence of CDs at 500 nm owing to the inner filter effect; OTC behaved similarly, but the emission wavelength of CDs was red-shifted to 515 nm. Inversely, once CTC was introduced to CDs solution, the fluorescence increased and the emission peak was blue-shifted to 450 nm. Bandgap transition and electrostatic interaction were proposed to be the mechanisms for the detection of OTC and CTC by CDs. Wide linear relationships were established for TC, OTC, and CTC with the limits of detection to be 50 nM, 36 nM, and 373 nM, respectively. Furthermore, the nanoscale probe constructed by this system has been applied to detect tetracyclines (TCs) in complex samples with satisfying recoveries (93.2-114%) and was designed as a portable test strip sensor for visually on-site TCs of honey sample screening. Accordingly, the preparation process of the nano fluorescent probe is simple and environmentally friendly, and the probe has a specific recognition ability for tetracyclines. The synthesized CDs in this work provide a new orientation for fast, effective, and visual real-time detection of tetracycline in actual samples.

Sensitive homogeneous fluorescent detection of DNA glycosylase by target-triggering ligation-dependent tricyclic cascade amplification

Abnormal DNA glycosylases are concerned with the aging process as well as numerous pathologies in humans. Herein, a sensitive fluorescence method utilizing target-induced ligation-dependent tricyclic cascade amplification reaction was developed for the detecting DNA glycosylase activity. The presence of DNA glycosylase triggered the cleavage of damaged base in hairpin substrate, successively activating ligation-dependent strand displacement amplification (SDA) and exponential amplification reaction (EXPAR) for the generation of large amount of reporter probes. The resultant reporter probes bound with the signal probes to form stable dsDNA duplexes. And then the signal probes could be digested circularly in the dsDNA duplexes by T7 exonuclease, leading to the generation of an enhanced fluorescence signal. Due to the high efficiency of tricyclic cascade amplification and the low background signal deriving from the inhibition of nonspecific amplification, this method exhibited a detection limit of 0.14 U/mL and a dynamic range from 0.16 to 8.0 U/mL. Moreover, it could be applied for detecting DNA glycosylase activity in human serum with good selectivity and high sensitivity, and even quantifying other types of enzyme with 5'-PO₄ residue cleavage product by rationally designing the corresponding substrate. Importantly, this method could be performed in homogenous solution without any complicated separation steps, providing a new strategy for DNA glycosylase-related biomedical research.

Determination of the concentration of transcription factor by using exonuclease III-aided amplification and gold nanoparticle mediated fluorescence intensity: A new method for gene transcription related enzyme detection

Herein, we report a new probe for the determination of the concentration of NF-κB p50, one kind of DNA-binding transcription factors (TFs), by using Exonuclease III (Exo III)-aided amplification and gold nanoparticle mediated fluorescence intensity. Since TFs play critical roles in various biological processes, the detection of TFs can provide a lot of useful biological information for studding gene expression regulation related disease. In our system, in the presence of transcription factor, Exo III based amplification reaction was trigged. This enzymatic digestion results in the release of intermediate DNA and ultimately liberating the fluorophore (which, separated from the quencher of AuNP and BHQ2, now fluoresces). The released intermediate DNA then hybridizes with another strand3, whence the cycle starts anew. So, the fluorescence intensity reflects the NF-κB p50 concentration with a detection limit of 1.32 pM. Importantly, this method might be further extended to selectively detect various dsDNA-binding proteins by simply changing the binding-site sequences of strand1/strand2 duplex probes.

4-Quinolone-Carboxamide and Carbothioamide Compounds as Fluorescent Sensors. New Fluorimetric Methods for Cu2+ and Fe3+ Determination in Tap Water and Soil

Ion sensor properties of the carboxamide and carbothioamide compounds carrying 4-quinolone group were investigated by means of emission spectrometry in methanol-water (1:1). The compounds were selectively complexed with Cu²⁺, Pd²⁺, and Fe³⁺ among many metal ions. The complex stoichiometry and the stability constant were determined by fluorimetric measurements. The carboxamide compound having phenyl group (QPO) showed sensitivity for Fe³⁺ ion with a linear range between 0.1 and 0.7 mg/L. The new method was applied in the determination of iron in the spiked tap water samples and the sandy-soil reference material. A modified standard addition method was used to remove the matrix effect. Limit of detection was 0.03 mg/L for the Fe³⁺ determination method. The carboxamide compound with benzyl group (QBO) showed sensitivity for Cu²⁺ ion with linear range 0-0.4 mg/L. There was no matrix effect for copper determination in the spiked tap water samples. The detection limit of the method for Cu²⁺ ion was 0.05 mg/L. The quantification limits of the methods were low enough to determine iron and copper amount in drinking water samples according to EPA.

A label-free fluorescent probe for the detection of adenosine 5'‑triphosphate via inhibiting the aggregation-induced emission enhancement of glutathione modified silver nanoclusters triggered by zinc ion

It is important to establish sensitive and simple analysis methods for adenosine 5'‑triphosphate (ATP). A label-free fluorescent probe for the determination of ATP was constructed based on glutathione modified silver nanoclusters (AgNCs/GSH). AgNCs/GSH showed aggregation-induced emission enhancement (AIEE) property in the organic solvent. The effects of metal ions on the fluorescence of AgNCs/GSH were also studied. Only zinc ion enhanced the fluorescence of AgNCs/GSH obviously. This was because Zn²⁺ coordinated with AgNCs/GSH to cause the aggregation of AgNCs/GSH, which was sufficiently proved by TEM. With the addition of ATP, Zn²⁺ bound with ATP through ZnOP bond and the binding between Zn²⁺ and AgNCs/GSH was inhibited. Hence the fluorescence of AgNCs/GSH was decreased with increasing the ATP concentration. The fluorescence response was linear in the ATP concentration range of 1-110 μM, and the detection limit was 0.8 μM. Then this method was successfully applied for determining ATP in the samples of human urine and rat serum, the recoveries were in the range of 97.6%-103%.

Target-mediated hyperbranched amplification for sensitive detection of human alkyladenine DNA glycosylase from HeLa cells

Human alkyladenine DNA glycosylase (hAAG) is an important protein enzyme which can specifically recognize and initiate the repair of a variety of alkylated purines and hypoxanthine, and the dysregulation of hAAG activity is associated with various human diseases. Although there are several methods focusing on hAAG detection, they share common defects such as time-consuming protocols, laborious operation or requirement of expensive analytical instruments. Herein, taking advantage of the high amplification efficiency of hyperbranched signal amplification and the low background signals by modifying NH₂ at 3' terminus of hairpin substrate and signal probe to prevent the terminal deoxynucleotidyl transferase (TdT)-activated nonspecific amplification, a fluoresence method for sensitive detection of hAAG was established using TdT-activated Endonuclease IV (Endo IV)-assisted hyperbranched signal amplification. This method exhibits high sensitivity with a limit of detection of 0.090 U/mL for pure hAAG and shows a large dynamic range of 3 orders of magnitude from 0.1 to 50 U/mL, and it can be applied for accurate detection of hAAG in complicated HeLa nuclear extract. Moreover, the method can be used for discrimination of hAAG from other DNA glycosylases, holding great potential in hAAG-related biomedical research and clinical diagnosis.

Fluorescence method for quickly detecting ochratoxin A in flour and beer using nitrogen doped carbon dots and silver nanoparticles

In this paper, a FRET (Forster resonance energy transfer) based fluorescence method was developed for the quickly detection of ochratoxin A (OTA) in agricultural products (e.g., flour and beer). A highly fluorescent nitrogen doped carbon dots (CD) were served as energy donor, the DNA and MCH (6-mercapto-1-hexanol) modified Ag nanoparticles were served as energy acceptor in the FRET system. OTA can be detected in a concentration range between 10 and 5000 nM, the limit of detection is 8.7 nM. This method has three advantages: (1) an enhanced fluorescent intensity can be acquired by utilizing the nitrogen doped CD synthesized by one-step approach without sophisticated modification of nanoparticles; (2) OTA detection was accomplished quickly (less than 30 min) by using MCH as assistant molecule; (3) an extended OTA detection linear range was acquired, which may facilitate the OTA detection in real agricultural samples, and is helpful for solving food safety problems.