Fruit waste (Pulp) decorated CuO NFs as promising platform for enhanced catalytic response and its peroxidase mimics evaluation

Herein, we report for the first time, an eco-compatible hydrothermal route for the synthesis of carbon enriched mesoporous material (CuO NFs@MP) using fruit waste (Pulp) obtained from Citrus limetta’s (Mausambi) decorated irregular shaped CuO nanoflakes (NFs). The CuO NFs@MP nanocomposite was fully characterized through several spectroscopic-cum-analytical techniques such as TEM and XPS, which further confirmed the presence of CuO NFs. CuO NFs@MP could serve as an excellent catalyst for N-Arylation reaction and also paves promising peroxidase mimic activity. The preliminary results indicated that CuO NFs@MP shows the catalytic advantage of higher yields, shorter reaction time and greener conditions. Simultaneously, the oxidation of colorless TMB with H₂O₂ into blue-green colored ox-TMB was also observed in 60 s with CuO NFs@MP. The present nanocomposite is easy to synthesize, economical, retrievable and a reusable catalyst for synthesizing a varied range of N-Arylated products and could also mimic peroxidase without significant loss of activity.     

Construction and application of carbon nanotube/polypyrrole-based bacterial surface imprinted sensorEI北大核心CSCD

A simple and fast "non-hole" bacteria surface imprinted (SPBIP) impedance sensor was constructed for ultrasensitive detection of Salmonella. The SPBIP sensor was prepared by one step electropolymerization of pyrrole (functional monomer), single-walled carbon nanotube (SWNT, nano-modulator), and Salmonella(template) onto a glassy carbon electrode. After removing the bacterial template, "non-hole" imprinted sites were formed on the surface of the polymer matrix, allowing the target bacteria to be specifically recognized. The resulting changes in the electrode surface impedance could be used to detect the target bacteria. The effects of the amount of SWNT, polymerization cycles, eluents, elution time and recognition time on the recognition ability of the sensor were investigated. Under the optimal conditions, the sensor could be used to detect 10~1×107 CFU/mLSalmonella with the limit of detection of 3.5 CFU/mL. The sensor could be used for the detection of salmonella in drinking water and orange juice samples with the recoveries ranging from 95.4% to 109.5%. © 2023, Youke Publishing Co.,Ltd. All rights reserved.     

Analysis of steroidal glycoalkaloids and their metabolites in Solanum nigrum fruits based on liquid chromatography-tandem mass spectrometry and molecular networking

Solanum nigrum fruit is like a treasure house for anticancer drugs because of its steroidal alkaloids. However, the clinical treatment of cancer mainly uses immature fruits, which can cause a toxic reaction if eaten directly, while mature fruits are eaten as fruit. In order to clarify the reasons for the differences in pharmacodynamics and toxicity between them, we studied the composition and metabolism of steroidal alkaloids in fruits of different maturities based on liquid chromatography-tandem mass spectrometry and molecular networking. As a result, 114 steroidal glycoalkaloids were identified. During fruit ripening, the aglycones of steroidal alkaloids mainly undergo hydroxylation and carboxylation, and the sugar side chains mainly undergo acylation and glycosylation reactions. Furthermore, 219 steroidal alkaloids were identified in a metabolism experiment in rats. Metabolic processes include deglycosylation, redox, sulfuric acid binding, acetyl binding, and glucuronic acid-binding. Steroidal alkaloids in mature fruits have high molecular weight and polarity, which are difficult to absorb, and most of them are excreted through feces and urine, which may be the reason for their poor efficacy. This study lays a foundation for research on the biosynthesis of steroidal alkaloids and provides potential candidates for the discovery of new steroidal alkaloid anticancer drugs.     

Ultra Sensitive Quantification of Thiourea at Nanomolar Level by Catalytic‐Kinetic Differential Pulse Voltammetry

A new simple and highly selective and sensitive catalytic differential pulse voltammetry procedure for the determination of thiourea at nanomolar level is reported. Thiourea has a catalytic effect on the oxidation of Janus green by iodate in the hydrochloric acid medium. The potential was scanned in the negative direction and the differential pulse voltammograms were recorded. The variations of the peak current with hydrochloric acid concentration, oxidant, Janus green, pulse amplitude, pulse time and scan rate were optimized. Under the optimized conditions, the relationship between the peak current and concentration of thiourea was obtained. It is shown that the calibration curve is linear in the range of 0.01–6.00 µg/mL. The detection limit of the method was 0.005 µg/mL. The relative standard deviation for 6 replicate determinations of 0.01, 0.50 and 2.00 µg/mL is equal to 2.25%, 1.52% and 1.03%, respectively. The method was applied to the determination of thiourea in fruit juices with satisfactory results.     

菠萝蛋白酶催化合成寡聚L-酪氨酸

以菠萝蛋白酶为催化剂从L-酪氨酸甲酯聚合得到寡聚L-酪氨酸(O-L-Try)。 以0.8 U/mL蛋白酶在体积分数为7.5%的二甲亚砜(DMSO)缓冲液(pH=7.5,0.2 mol/L)中催化0.23 g/mL L-酪氨酸甲酯在50 ℃下聚合反应5 h后,O-L-Try产率达到65%。 通过基质辅助激光解吸电离飞行时间质谱(MALDI-TOF-MS)、氢核磁共振波谱仪(¹H NMR)、拉曼光谱、傅里叶变换红外光谱仪(FTIR)等技术手段表征了O-L-Try结构和性能特征。 结果表明,MALDI-TOF-MS测定的O-L-Try的聚合度主要为10。 ¹H NMR谱图分析得到的O-L-Try的平均聚合度为8。 拉曼光谱显示,O-L-Try的肽键特征峰位于1623 cm^-1(酰胺Ⅰ带)、1447 cm^-1(酰胺Ⅱ带)、1270 cm^-1(酰胺Ⅲ带)和648 cm^-1(酰胺Ⅳ带)。     

Novel modified carbon nanotubes as a selective sorbent for preconcentration and determination of trace copper ions in fruit samples

In this work, multiwalled carbon nanotubes were reacted with N‐[3‐(triet‐hoxysilyl)propyl]isonicotinamide to prepare pyridine‐functionalized carbon nanotubes. This novel sorbent was characterized by infrared spectroscopy, thermal and elemental analysis, and scanning electron microscopy. Functionalized carbon nanotubes were applied for the preconcentration and determination of copper ions using flame atomic absorption spectrometry. Various parameters such as sample pH, flow rate, eluent type and concentration, and its volume were optimized. Under optimal experimental conditions, the limit of detection, the relative standard deviation, and the recovery of the method were 0.65 ng/mL, 3.2% and 99.4%, respectively. After validating the method using standard reference materials, the new sorbent was applied for the extraction and determination of trace copper(II) ions in fruit samples.     

Peptide prefractionation is essential for proteomic approaches employing multiple‐reaction monitoring of fruit proteomic research

Off‐gel? IEF has become a popular tool in proteomics research to fractionate peptides or proteins. We conducted a detailed investigation on the fruit proteomics of apple, banana, and strawberry fruit employing Off‐gel? electrophoresis (OGE) as a crucial step to improve the proteome coverage and quantitative proteomic workflows including multiple‐reaction monitoring (MRM). We provide technical details concerning the application of Off‐gel?IEF, nano‐LC–MS detection, and MRM optimization and analysis. Our results demonstrated that the application of OGE is an effective method for peptide fractionation and increased significantly the number of proteins identified by at least ten times, with more total peptides detected and collected. Furthermore, we developed a protocol combining OGE and MRM studies to identify and quantitatively investigate monodehydroascorbate reductase, a key enzyme in the redox and antioxidant system of apple fruit during fruit ripening. Using this method, the quantitative changes in this protein during ripening and in response to ethylene treatment was investigated. Our results provide direct and comprehensive evidence demonstrating the benefits of OGE and its application for both shotgun and quantitative proteomics research.     

High performance ethylene sensor based on palladium-loaded tin oxide: Application in fruit quality detection

Ethylene (C₂H₄), as a plant hormone, its emission can be served as an indicator to measure fruit quality. Due to the limited physiochemical reactivity of C₂H₄, it is a challenge to develop high performance C₂H₄ sensors for fruit detection. Herein, this paper presents a resistive-type C₂H₄ sensor based on Pd-loaded tin oxide (SnO₂). The C₂H₄ sensing performance of proposed sensor are tested at optimum operating temperature (250 °C) with ambient relative humidity (51.9% RH). The results show that the response of Pd-loaded SnO₂ sensor (11.1, R_a/R_g) is about 3 times higher than that of pristine SnO₂ (3.5) for 100 ppm C₂H₄. The response time is also significantly shortened from 7 s to 1 s compared with pristine SnO₂. Especially, the Pd-loaded SnO₂ sensor possesses good sensitivity (0.58 ppm⁻¹) at low concentration (0.05–1 ppm) with excellent linearity (R² = 0.9963) and low detection limit (50 ppb). The high sensing performance of Pd-loaded SnO₂ are attributed to the excellent adsorption and catalysis effects of Pd nanoparticle. Meaningfully, the potential applications of C₂H₄ sensor are performed for monitoring the maturity and freshness of fruits, which presents a promising prospect in fruit quality evaluation.     

Accumulation of selected metals in the fruits of medicinal plants grown in urban environment of Islamabad,Pakistan

The present study is based on the measurement of selected metals (Ca, Cd, Co, Cr, Cu, Fe, Mg, Mn, Pb, Sr and Zn) in the fruits of eight medicinal plants (Carrisa opeca, Phyllanthus emblica, Solanum nigrum, Zizyphus nummularia, Zizyphus mauritiana, Physalis minima, Opuntia dillenii and Phoenix dactylifera) and relevant soil samples by atomic absorption spectrometry. Highest average concentrations of Cu (14.4 mg/kg), Cr (19.0 mg/kg), and Zn (125 mg/kg) were found in the fruits of P. minima, C. opeca and Z. nummularia, respectively, while O. dillenii showed the elevated mean levels of Cd (3.49 mg/kg), Sr (61.4 mg/kg), Mg (0.21%), Ca (6.62%) and Mn (44.6 mg/kg). However, highest average levels of Pb (41.7 mg/kg) and Co (38.4 mg/kg) were found in Z. mauritiana. Overall, most of the fruit samples showed higher contributions of Ca and Mg, followed by Fe, Zn, Co and Pb. In the case of soil samples, highest concentration was observed for Ca, followed by Fe, Mg, Mn and Sr, while lowest concentration was shown by Cd. Bioaccumulation factors exhibited significantly higher accumulation of Co (0.813–1.829) and Pb (0.060–2.350) from the soil to the fruits. Principal component analysis revealed significant anthropogenic contributions of Pb, Fe and Co in the fruit samples. Contamination factors and enrichment factors of Cd and Pb in the soil indicated very high contamination and extreme enrichment of these metals.     

Micellar capillary electrophoresis – Electrochemical detection of neurochemicals from Drosophila

The fruit fly is one of the most heavily studied model organisms for genetics research and has significantly contributed to the molecular, cellular, and evolutionary understandings of human behavior. Recent research in the analytical chemistry of the fruit fly has focused on developing methods to obtain highly sensitive chemical quantification information of Drosophila melanogaster, especially looking at the nervous system. We provide a brief overview of work in the area of CE of the fly head and brain.