FT-IR and NIR spectroscopic investigation of hydrogen bonding in indole-ether systems

Composite aerogel membranes with well dispersed nano M-TiO2@GO for efficient photocatalysis

Photocatalytic technology plays a crucial role in addressing energy shortages and environmental pollution. TiO2 has been widely applied in photocatalysis but encounters several issues, such as the easy recombination of photoexcited electrons and holes, the poor dispersion uniformity, the wide band gap, and the complex recovery process. In this work, a recyclable M-TiO2@GO/modified chitosan composite aerogel membrane was designed and prepared for photocatalytic application, with TiO2 nanoparticles generated by MXene oxidation (M-TiO2) serving as the photocatalyst and modified chitosan acting as the matrix. The experimental results demonstrated that M-TiO2 nanoparticles were in situ generated on the surface of graphene oxide (GO) nanosheets, forming M-TiO2@GO nanoparticles with a 0D@2D structure. Due to the combined effects of M-TiO2 and carbon (another product resulting from the oxidation of MXene), the band gap of M-TiO2 nanoparticles was decreased from 3.10 eV to 2.06 eV, which significantly enhanced the photocatalytic efficiency of TiO2. When the photocatalytic degradation performance of the aerogel membrane containing M-TiO2@GO nanoparticles was evaluated, the sample C15M15G5 (containing modified chitosan 15 mg/M-TiO2 15 mg/GO 5 mg) demonstrated nearly complete degradation of Rhodamine B and Acid Blue 1 within 120 min, exhibiting excellent photocatalytic performance. In addition, the antibacterial properties of C15M15G5 were examined and found that the antibacterial rate reached 100% following ultraviolet irradiation. In summary, this study presents an innovative strategy to obtain well-dispersed nano TiO2, which can be used to prepare composite photocatalytic aerogel membranes with excellent catalytic performance and complete recyclability.

Influence of the hydrophobic polyhydroxyethyl methacrylate branches grafted with high amylose corn starch on the properties of its electrospun drug-loaded membranes

The nanofiber membranes based on native starch are prone to swelling or dissolution after contact with water, and the fragile starch membranes, due to the aging of molecular chains, are unsuitable for medical dressings. Herein, the hydrophobic polyhydroxyethyl methacrylate (PHEMA) branches in different ratios were grafted onto high amylose corn starch (HACS) using a redox system. Furthermore, electrospun aspirin-loaded nanofiber membranes were prepared and investigated in terms of porosity, swelling capacity, water vapor transmittance rate (WVTR), cumulative release rate, and cytotoxicity. The results confirmed that with increasing grafting ratio, the porosity and WVTR of the HACS-g-PHEMA drug-loaded membrane gradually increased, while swelling capacity slightly decreased from 746.2% to 619.9%, and the cumulative release rate decreased from 56.21% to 32.54% in 2 h. The Ritger-Peppas mathematical model fitting found that the diffusion coefficients of drug-loaded membranes were less than 0.45, which belonged to the Fick diffusion behavior. After the grafting of PHEMA branches, the hydrophobic interaction between starch molecular chains and aspirin was enhanced, and the nanofiber membrane defects were alleviated while still maintaining good biocompatibility. This study provides a foundation for the sustained release of hydrophobic drugs in starch-based medical dressings.

New insights into the interactions between the antibiotic enrofloxacin and fish protein by spectroscopic, thermodynamic, and theoretical simulation approaches

In this study, myofibrillar proteins (MPs) from crucian carp were utilized as a model to investigate the binding mechanism between fish proteins and antibiotic residues. Fluorescence quenching confirmed the static quenching (Ksv = 1.89 × 104 M-1 s-1, Kq = 1.89 × 1012 M-1 s-1) and effective binding (Kb = 5.66 × 106 M-1) of Enrofloxacin (ENRO) to MPs. Fourier-transform infrared spectroscopy and circular dichroism spectroscopy revealed that ENRO binding altered the secondary structure of MPs. The interaction mechanism, primarily driven by hydrogen bonding, electrostatic, and hydrophobic interactions (ΔH0 < 0, ΔS0 > 0), was elucidated using isothermal titration calorimetry. The ΔH0, -TΔS0 and ΔG0 values of the binding reaction between MPs and ENRO were -5.98 kJ/mol, -32.57 kJ/mol and -38.55kJ/mol. Molecular docking further verified the interaction forces, identifying key amino acid residues (Phe-40, His-93, and Lys-42) involved in ENRO binding. Additionally, protein carbonylation results demonstrated that even at maximum residue limits, ENRO accelerated MPs oxidation, further confirming the binding of the two. This study can provide theoretical support for the research of the dissipation fate of bound state residues in aquatic products.

Efficient Decomposition of Perfluoroalkyl Substances by Low Concentration Indole: New Insights into the Molecular Mechanisms

Perfluoroalkyl substances (PFAS) are a class of persistent organic pollutants known as "forever chemicals". Currently, the hydrated electron-based advanced reduction process (ARP) holds promise for the elimination of PFAS. However, the efficiency of ARP is often challenged by an oxygen-rich environment, resulting in the consumption of hydrated electron source materials in exchange for the high PFAS decomposition efficiency. Herein, we developed a ternary system constructed by indole and isopropyl alcohol (IPA), and the addition of IPA significantly enhanced the PFOA degradation and defluorination efficiency in the presence of low-concentration indole (<0.4 mM). Meanwhile, opposite results were obtained with a higher amount of indole (>0.4 mM). Further exploring the molecular mechanism of the reaction system, the addition of IPA played two roles. On one hand, IPA built an anaerobic reaction atmosphere and improved the yield and utilization efficiency of hydrated electrons with a low concentration of indole. On the other hand, IPA suppressed the attraction between indole and PFOA, thus reducing the hydrated electron transfer efficiency, especially with more indole. In general, the indole/PFAS/IPA system significantly improved the PFAS destruction efficiency with a small amount of hydrated electron donors, which provided new insights for development of simple and efficient techniques for the treatment of PFAS-contaminated wastewater.

Highly Efficient Hydrated Electron Utilization and Reductive Destruction of Perfluoroalkyl Substances Induced by Intermolecular Interaction

Perfluoroalkyl substances (PFASs) are highly toxic synthetic chemicals, which are considered the most persistent organic contaminants in the environment. Previous studies have demonstrated that hydrated electron based techniques could completely destruct these compounds. However, in the reactions, alkaline and anaerobic conditions are generally required or surfactants are involved. Herein, we developed a simple binary composite, only including PFAS and hydrated electron source chemical. The system exhibited high efficiency for the utilization of hydrated electrons to decompose PFASs. By comparing the degradation processes of perfluorooctanoic acid (PFOA) in the presence of seven indole derivatives with different chemical properties, we could conclude that the reaction efficiency was dependent on not only the yield of hydrated electrons but also the interaction between PFOA and indole derivative. Among these derivatives, indole showed the highest degradation performance due to its relatively high ability to generate hydrated electrons, and more importantly, indole could form a hydrogen bonding with PFOA to accelerate the electron transfer. Moreover, the novel composite demonstrated high reaction efficiency even with coexisting humic substance and in a wide pH range (4-10). This study would deepen our understanding of the design of hydrated electron based techniques to treat PFAS-containing wastewater.

Assessing the Quality of Milk Using a Multicomponent Analytical Platform MicroNIR/Chemometric

In this work, an innovative screening platform based on MicroNIR and chemometrics is proposed for the on-site and contactless monitoring of the quality of milk using simultaneous multicomponent analysis. The novelty of this completely automated tool consists of a miniaturized NIR spectrometer operating in a wireless mode that allows samples to be processed in a rapid and accurate way and to obtain in a single click a comprehensive characterization of the chemical composition of milk. To optimize the platform, milk specimens with different origins and compositions were considered and prediction models were developed by chemometric analysis of the NIR spectra using Partial Least Square regression algorithms. Once calibrated, the platform was used to predict samples acquired in the market and validation was performed by comparing results of the novel platform with those obtained from the chromatographic analysis. Results demonstrated the ability of the platform to differentiate milk as a function of the distribution of fatty acids, providing a rapid and non-destructive method to assess the quality of milk and to avoid food adulteration.

Development of a "single-click" analytical platform for the detection of cannabinoids in hemp seed oil

In this work, an innovative screening platform is developed and validated for the on site detection of cannabinoids in hemp seed oil, for food safety control of commercial products. The novelty of this completely automated tool consists of a miniaturized NIR spectrometer operating in a wireless mode that permits processing samples in a rapid and accurate way and to obtain in a single click the early detection of a residual amount of cannabinoids in oil, including cannabidiol (CBD), the psychoactive Δ9-tetrahydrocannabinol (THC) and the Δ9-tetrahydrocannabinolic acid (THCA). Simulated samples were realized to instruct the platform and prediction models were developed by chemometric analysis of the NIR spectra using partial least square regression algorithms. Once calibrated, the platform was used to predict samples acquired in the market and on websites. Validation of the system was achieved by comparing results with those obtained from GC-MS analyses and a good correlation was observed.

The detection of cannabinoids in veterinary feeds by microNIR/chemometrics: a new analytical platform

In this work, the capabilities of a novel miniaturized and portable microNIR spectrometer were investigated in order to propose a practical and intelligible test allowing the rapid and easy screening of cannabinoids in veterinary feeds. In order to develop a predictive model that could identify and simultaneously quantify the residual amounts of cannabinoids, specimens from popular veterinary feeds were considered and spiked with increasing amounts of cannabidiol (CBD), Δ9-tetrahydrocannabinol (THC), and cannabigerol (CBG). Partial least squares discriminant analysis (PLS-DA) and partial least squares regression (PLSr) were applied for the simultaneous detection and quantification of cannabinoids. The results demonstrated that the microNIR/chemometric platform could statistically identify the presence of CBD, THC and CBG in the simulated samples containing cannabinoids from 0.001 to 0.01%w/w, with the accuracy and sensitivity of the official reference methods actually proposed. The method was checked against false positive and true positive responses, and the results proved to be those required for confirmatory analyses, permitting to provide a fast and accurate method for monitoring cannabinoids in veterinary feeds.

Real time detection of amphetamine in oral fluids by MicroNIR/Chemometrics

In this work, a novel coupled approach MicroNIR/Chemometrics based on a miniaturized and portable spectrometer is proposed for the on site detection of amphetamines (AMP) in non pretreated oral fluids. In particular, the coupling of MicroNIR with chemometrics was investigated with the aim of developing a fast and accurate approach able to perform the on-site prediction of AMP abuse. A predictive model to be used in real cases was developed by collecting specimens from volunteers and spiked samples with increasing amounts of AMP were prepared to optimize calibration. Partial Least Square-Discriminant Analysis (PLS-DA) and Partial Least Square regression (PLS) were involved to detect and quantify AMP. Results demonstrated that MicroNIR/Chemometric platform is statistically able to identify AMP abuse in simulated oral fluid samples containing, with the accuracy and sensitivity of the actual proposed official reference methods. The method was checked against false positive and true positive response and results proved to be those required for confirmatory analyses. This method would permit to simplify AMP abuse monitoring for roadside drug testing or workplace surveillance and may be of help at first aid points.

MicroNIR/Chemometrics: A new analytical platform for fast and accurate detection of Δ9-Tetrahydrocannabinol (THC) in oral fluids

BACKGROUND

Δ⁹-Tetrahydrocannabinol (THC) is already considered one of the most addictive substances since an increasing number of consumers/abusers of THC and THC based products are observed worldwide. In this work, the capabilities of a novel miniaturized and portable MicroNIR spectrometer were investigated in order to propose a practical and intelligible test allowing the rapid and easy screening of Δ⁹-Tetrahydrocannabinol (THC) oral fluids without any pretreatment.

METHODS

Specimens from volunteers were collected in order to consider any sources of variability in the spectral response and spiked with increasing amount of THC in order to realize predictive models to be used in real cases. Partial Least Square-Discriminant Analysis (PLS-DA) and Partial Least Square regression (PLSr) for the simultaneously detection and quantification of THC, were applied to baseline corrected spectra pre-treated by first derivative transform.

RESULTS

Results demonstrated that MicroNIR/Chemometric platform is statistically able to identify THC abuse in simulated oral fluid samples containing THC from 10 to 100 ng/ml, with a precision and a sensitivity of about 1.51% and 0.1% respectively.

CONCLUSIONS

The coupling MicroNIR/Chemometrics permits to simplify THC abuse monitoring for roadside drug testing or workplace surveillance and provides the rapid interpretation of results, as once the model is assessed, it can be used to process real samples in a "click-on" device.

Facile Preparation of Metal-Organic Framework (MIL-125)/Chitosan Beads for Adsorption of Pb(II) from Aqueous Solutions

In this study, novel composite titanium-based metal-organic framework (MOF) beads were synthesized from titanium based metal organic framework MIL-125 and chitosan (CS) and used to remove Pb(II) from wastewater. The MIL-125-CS beads were prepared by combining the titanium-based MIL-125 MOF and chitosan using a template-free solvothermal approach under ambient conditions. The surface and elemental properties of these beads were analyzed using scanning electron microscopy, Fourier transform infrared and X-ray photoelectron spectroscopies, as well as thermal gravimetric analysis. Moreover, a series of experiments designed to determine the influences of factors such as initial Pb(II) concentration, pH, reaction time and adsorption temperature was conducted. Notably, it was found that the adsorption of Pb(II) onto the MIL-125-CS beads reached equilibrium in 180 min to a level of 407.50 mg/g at ambient temperature. In addition, kinetic and equilibrium experiments provided data that were fit to the Langmuir isotherm model and pseudo-second-order kinetics. Furthermore, reusability tests showed that MIL-125-CS retained 85% of its Pb(II)-removal capacity after five reuse cycles. All in all, we believe that the developed MIL-125-CS beads are a promising adsorbent material for the remediation of environmental water polluted by heavy metal ions.