Selectivity Quantification with the Fluorescent Quantitative Model-Assisted Semi-Selective Probe (Carbon Dots): Accurate Determination of Chlortetracycline in Aqueous Environments with Interference.

Probes such as carbon dots (C-dots) have extensive and important applications in the quantitative analysis of complex biological and environmental systems. However, the development of probes is often hindered by incomplete selectivity, i.e., a probe that responds to one substance is also prone to respond to coexisting structurally similar substances. Therefore, the above dilemma often leads to be developed as semi-selective probes, so that the development of probes is abandoned halfway. This work shows how a semi-selective probe can enhance selectivity by combining a proper multivariate calibration model. Primarily, we developed a semi-selective fluorescent probe that responded to tetracyclines (TCs) with discarded tobacco leaves. Then, we introduced the multivariate quantitative fluorescence model (QFM) to enhance its selectivity and solve the problem of fluorescence spectral shift. For the determination of chlortetracycline (CTC) with this semi-selective C-dots probe in mineral and lake water samples and compared to the traditional quantitative model, the introduced QFM resulted in an average relative predictive error (ARPE) in mineral water spiked samples decreased from 57.1 to 5.6%, which reduced the ARPE in the lake water spiked samples from 18.1 to 4.7%. The above results show that the QFM-assisted semi-selective probe C-dots strategy (QFMC-dots) can enhance selectivity, and QFMC-dots achieved high-selective and accurate determination of CTC in interfering mineral and lake water samples, with the limit of detection and limit of quantitation of 0.55 and 1.66 µM, respectively. The proposed strategy of enhancing selectivity by introducing a proper multivariate calibration model can reduce the difficulty and increase success rate of developing probes, which can be expected to provide an interesting alternative for the development of probes, especially when encountering semi-selective problems.

Waste tobacco leaves derived carbon dots for tetracycline detection: Improving quantitative accuracy with the aid of chemometric model.

The recycling and reutilization of biomass wastes are significant for environmental protection and sustainable development. Recently, there have many studies on utilizing biomass wastes to produce carbon dots. Whereas, the spectrum shift effect that occurs in the quantitative application of carbon dots as fluorescent probes limits the accuracy of the quantitative analysis. In this work, waste tobacco leaves were used as the carbon source for synthesizing a novel carbon dots (CDs(WTL)) through a facile hydrothermal method. The CDs(WTL) possess a series of excellent properties, including good water solubility, well stability, and high fluorescence quantum yield. The fluorescent intensity of the CDs(WTL) can be quenched by tetracycline (TC) obviously, but there is a spectrum shift. In order to use the CDs(WTL) as fluorescent probes to quantify TC with higher accuracy, a quantification fluorescence model (QFM) was introduced to overcome this spectrum shift effect that often occurs. The coefficient of determination (R2) of traditional quantification model (TQ), partial least squares (PLS), and QFM are 0.9672, 0.9834, and 0.9991, respectively; the average relative predictive error (ARPE) of TQ, PLS, and QFM are 8.8%, 4.5%, and 3.9% for the spiked water samples, and 21.9%, 22.0%, and 2.9% for spiked tablet samples, respectively. The obtained results suggest that QFM is more accurate than PLS and TQ for the TC detection. By utilizing QFM, the spike recoveries (mean ± standard deviation) in three kinds of real tablet samples produced by different manufacturers are 98.9 ± 3.6%, 102.5 ± 6.2%, and 98.5 ± 2.7%, respectively; the spike recovery in river water samples is 99.4 ± 5.0%. In addition, high performance liquid chromatography (HPLC) was used as a reference method, the F and t tests suggest that there are no significant differences on the precision and accuracy between QFM and HPLC methods.

A Review of Carbon Dots Produced from Biomass Wastes.

The fluorescent carbon dot is a novel type of carbon nanomaterial. In comparison with semiconductor quantum dots and fluorescence organic agents, it possesses significant advantages such as excellent photostability and biocompatibility, low cytotoxicity and easy surface functionalization, which endow it a wide application prospect in fields of bioimaging, chemical sensing, environmental monitoring, disease diagnosis and photocatalysis as well. Biomass waste is a good choice for the production of carbon dots owing to its abundance, wide availability, eco-friendly nature and a source of low cost renewable raw materials such as cellulose, hemicellulose, lignin, carbohydrates and proteins, etc. This paper reviews the main sources of biomass waste, the feasibility and superiority of adopting biomass waste as a carbon source for the synthesis of carbon dots, the synthetic approaches of carbon dots from biomass waste and their applications. The advantages and deficiencies of carbon dots from biomass waste and the major influencing factors on their photoluminescence characteristics are summarized and discussed. The challenges and perspectives in the synthesis of carbon dots from biomass wastes are also briefly outlined.

Enhancing the selectivity of liquid chromatography-mass spectrometry by using trilinear decomposition on LC-MS data: An application to three-way calibration of coeluting analytes in human plasma.

The high selectivities of liquid chromatography and mass spectrometry make liquid chromatography-mass spectrometry one of the most popular tools for quantitative analysis in complex chemical, biological, and environmental systems, while the potential mathematical selectivity of liquid chromatography-mass spectrometry is rarely investigated. This work discussed the mathematical selectivity of liquid chromatography-mass spectrometry by three-way calibration based on the trilinear model, with an application to quantitative analysis of coeluting aromatic amino acids in human plasma. By the trilinear decomposition of the constructed liquid chromatography-mass spectrometry-sample trilinear model and individual regression of the decomposed relative intensity versus concentration, the proposed three-way calibration method successfully achieved quantitative analysis of coeluting aromatic amino acids in human plasma, even in the presence of uncalibrated interferent(s) and a varying background. This analytical method can ease the requirements for sample preparation and complete chromatographic separation of components, reduce the use of organic solvents, decrease the time of chromatographic separation, and increase the peak capacity of liquid chromatography-mass spectrometry. As a "green analytical method", the liquid chromatography-mass spectrometry three-way calibration method can provide a promising tool for direct and fast quantitative analysis in complex systems containing uncalibrated spectral interferents, especially for the situation where the coelution problem is difficult to overcome.

Simultaneously quantifying intracellular FAD and FMN using a novel strategy of intrinsic fluorescence four-way calibration.

The simultaneous quantitative analysis of intracellular metabolic coenzymes flavin adenine dinucleotide (FAD) and flavin mononucleotide (FMN) is of interest because they participate in many electron-transfer reactions of metabolism. But, the simultaneous quantitative analysis of FAD and FMN is hard to be achieved by traditional analytical methods. This paper proposes a novel strategy of intrinsic fluorescence coupled with four-way calibration method for simultaneous quantitative analysis of intracellular metabolic coenzymes FAD and FMN. Through mathematical separation, this proposed analytical method efficiently achieved the simultaneous quantitative analysis of metabolic coenzymes FAD and FMN in the cell, despite the fact that uncalibrated spectral interferents coexist in the system. The predicted concentrations of FAD and FMN in the cell are 217.0 ±â€¯6.9 and 155.0 ±â€¯1.7 pmol/106 cells respectively, which were validated by the approved liquid chromatography-tandem mass spectrometry (LC-MS/MS) method. This analytical method with second-order advantage simply requires the cell solution to be diluted by a buffer, it could introduce an interesting analytical strategy for multianalyte direct quantitative analysis in complex biological systems. In addition, we explore the third-order advantage of four-way calibration by a comparative study based on this real fluorescence data. The comparisons indicate that a four-way calibration method can provide higher sensitivity and more resolving power than a three-way calibration method.

Generalized ratiometric fluorescence nanosensors based on carbon dots and an advanced chemometric model.

Probe encapsulated by biologically localized embedding (PEBBLE) has emerged as a new type of sensing technique for complex systems. Generalized ratiometric PEBBLE nanosensors prepared by encapsulating an intensity-based probe and an inert reference dye inside the pores of stable matrix possess advantages of easy synthesis, immunity to interference, lower toxicity, and robustness to variations in probe loading. However, the selection of appropriate reference dyes used in generalized ratiometric PEBBLE nanosensors is a rather difficult task since they should satisfy some stringent requirements. In this contribution, the feasibility of using carbon dots (C-dots) as generic inert references in synthesizing PEBBLE nanosensors was first investigated in detail. And a dual-wavelength monitoring strategy and the quantitative fluorescence model for generalized ratiometric probes (QFMGRP) were adopted to solve the problems brought by the use of carbon dots as inert references. C-dots doped PEBBLE nanosensors (C-PEBBLE nanosensors) for the quantification of NO2- and free Ca2+ were synthesized by encapsulating C-dots and intensity based fluorescence probes (i.e., acriflavine for NO2-, and Rhod-2 for Ca2+, respectively) inside the pores of stable matrix. Experimental results showed that the combination of C-PEBBLEs, the QFMGRP model and the dual-wavelength monitoring strategy achieved accurate quantification of NO2- and the free Ca2+ in real-world samples. Their quantitative results were in good consistence with those determined by HPLC and atomic absorption spectrophotometer, respectively. The strategies proposed in this contribution have generic applicability in the synthesis of PEBBLE nanosensors and their quantitative applications.

Meta-analysis of laparoscopic versus open liver resection for hepatocellular carcinoma.

AIM: The aim of this study was to evaluate the surgical safety and effectiveness of laparoscopic hepatectomy (LH) in short- and long-term outcomes compared to open hepatectomy (OH) in patients treated for hepatocellular carcinoma (HCC). METHODS: An electronic search of reports published before August 2017 was carried out to identify comparative studies evaluating LH versus OH for HCC. RESULTS: A total of 5889 patients (2421 underwent LH; 3468 underwent OH) were included in our meta-analysis from 47 studies. Laparoscopic hepatectomies were associated with favorable outcomes in terms of operative blood loss (mean difference [MD], -147.27; 95% confidence interval [CI], -217.00, -77.55), blood transfusion requirement (odds ratio [OR], 0.51; 95% CI, 0.40, 0.65), pathologic resection margins (MD, 0.07; 95% CI, 0.02, 0.12; P = 0.01), R0 resection rate (OR, 1.34; 95% CI, 0.98, 1.84; P = 0.07), and length of hospital stay (MD, -5.13; 95% confidence interval, -6.23, -4.03). There were no differences between the groups in overall survival (OS) at 1 year (OR, 1.41; 95% CI, 1.00, 1.98), 3 years (OR, 1.12; 95% CI, 0.93, 1.36), or 5 years (OR, 1.18; 95% CI, 0.94, 1.46), in disease-free survival (DFS) at 1 (OR, 1.19; 95% CI, 0.94, 1.51), 3 years (OR, 1.07; 95% CI, 0.86, 1.33), or 5 years (OR, 1.13; 95% CI, 0.92, 1.40), or in recurrence (OR, 0.90; 95% CI, 0.74, 1.08). CONCLUSION: Compared to OH, LH is superior in terms of lower intraoperative blood loss and the requirement for blood transfusion, larger pathologic resection margins, increased R0 resection rates, and shorter length of hospital stay. Laparoscopic hepatectomy and OH have similar OS, DFS, and recurrence.

Quantitative generalized ratiometric fluorescence spectroscopy for turbid media based on probe encapsulated by biologically localized embedding.

PEBBLE (probe encapsulated by biologically localized embedding) nanosensor encapsulating an intensity-based fluorescence indicator and an inert reference fluorescence dye inside the pores of stable matrix can be used as a generalized wavelength-ratiometric probe. However, the lack of an efficient quantitative model render the choices of inert reference dyes and intensity-based fluorescence indicators used in PEBBLEs based generalized wavelength-ratiometric probes rather limited. In this contribution, an extended quantitative fluorescence model was derived specifically for generalized wavelength-ratiometric probes based on PEBBLE technique (QFMGRP) with a view to simplify the design of PEBBLEs and hence further extend their application potentials. The effectiveness of QFMGRP has been tested on the quantitative determination of free Ca(2+) in both simulated and real turbid media using a Ca(2+) sensitive PEBBLE nanosensor encapsulating Rhod-2 and eosin B inside the micropores of stable polyacrylamide matrix. Experimental results demonstrated that QFMGRP could realize precise and accurate quantification of free Ca(2+) in turbid samples, even though there is serious overlapping between the fluorescence excitation peaks of eosin B and Ca(2+) bound Rhod-2. The average relative predictive error value of QFMGRP for the test simulated turbid samples was 5.9%, about 2-4 times lower than the corresponding values of partial least squares calibration model and the empirical ratiometric model based on the ratio of fluorescence intensities at the excitation peaks of Ca(2+) bound Rhod-2 and eosin B. The recovery rates of QFMGRP for the real and spiked turbid samples varied from 93.1% to 101%, comparable to the corresponding results of atomic absorption spectrometry.

Interference-free determination of indole-3-acetic acid in two real systems using second-order calibration method coupled with excitation-emission matrix fluorescence.

In this work, a simple and practicable method that combines excitation-emission matrix (EEMs) fluorescence with a second-order calibration method based on parallel factor analysis-alternative least-squares (PARAFAC-ALS) algorithm was developed for the direct interference-free determination of indole-3-acetic acid (IAA) in two real systems, coconut water (CW) and coconut milk (CM). Although the excitation and emission profiles of IAA heavily overlapped with that of unknown interferents in the complex real systems, the actual contents and satisfactory recoveries were still obtained successfully. The contents of IAA in CW and CM were 10.8 ± 0.3 and 4.9 ± 0.2 µg mL(-1), respectively, which were consistent with those reported by LC-MS/MS assays in the reference material. The average spike recoveries of IAA in the validation set based on CW and CM were 102.1 ± 3.2 and 98.0 ± 1.9%, respectively. In addition, routine experiments were performed for establishing the validity of the assay to internationally accepted criteria.

Simultaneous determination of plant growth regulators in environmental samples using chemometrics-assisted excitation-emission matrix fluorescence: experimental study on the prediction quality of second-order calibration method.

In this work, with the purpose of developing an effective and inexpensive method, excitation-emission matrix fluorescence data and second-order calibration method based on the self-weighted alternating trilinear decomposition (SWATLD) algorithm were combined for simultaneous determination of 2-naphthoxyacetic acid (NOA) and 1-naphthaleneacetic acid methyl ester (NAAME) in environmental samples, i.e. soil and sewage samples. In order to investigate the prediction quality of the proposed method, different strategies, such as taking spectroscopic measurements in the presence of different matrix interferents and at different fluorescence spectrophotometers, were introduced to build calibration models and comparisons among them were done subsequently. The root-mean-square error of prediction and t-test were used to compare different SWATLD-based calibration models. The limits of detection obtained for NOA and NAAME were 0.36-0.95 ng mL(-1) and 1.32-2.69 ng mL(-1), respectively, for different models. Such a chemometrics-based protocol may possess great potential to be extended as a promising alternative for more practical applications in environment monitoring and for the design of small intelligent and field-portable analytical instruments that rely on statistical discrimination, not complete instrumental separation, of the target analytes even in the presence of unknown and uncalibrated interferences.