Amphiphilic nano-delivery system based on modified-chitosan and ovalbumin: Delivery and stability in simulated digestion.

Nano-delivery systems play an important role in the development of nutritional supplements due to their efficient encapsulation and delivery properties for nutrients. Herein, we prepared protein-polysaccharide nanoparticles as a novel amphiphilic nano-delivery system based on gallic acid modified chitosan (GCS) and ovalbumin (OVA) by pH-driven and calcium ion crosslinking. The nanoparticles loaded with hydrophilic riboflavin (Rib) and hydrophobic quercetin (Que) as nutrient models were abbreviated as GCS-OVA-Rib NPs and GCS-OVA-Que NPs, respectively. Their encapsulation efficiencies for Rib and Que. were 66.36 % and 96.61 %, respectively. In addition, GCS-OVA-Rib NPs and GCS-OVA-Que NPs showed antioxidant activity as well as good stability and delivery capacity for Rib and Que. in simulated digestion with release ratios of 78.38 % and 84.15 %, respectively. More importantly, GCS-OVA-Rib/Que. NPs performed good biocompatibility for further applications. Overall, this work provides some useful insights for the design of novel amphiphilic nano-delivery systems based on polysaccharides and proteins.

NiCu nanoalloy embedded in N-doped porous carbon composite as superior electrochemical sensor for neonicotinoid determination.

Enhancing catalytic activity is the key to develop electrochemical sensors for monitoring of neonicotinoid such as imidacloprid (IMI), thiamethoxam (THX) and dinotefuran (DNF). Herein, a MOF-derived octahedral NiCu nanoporous carbon composite with abundant N-doped (N/NiCu@C) was synthesized, which was exploited as electrochemical sensor for neonicotinoid determination. Integrating the synergistic effect of NiCu nanoalloy and the hierarchical porous carbon structure, the N/NiCu@C/GCE significantly promoted the diffusion between electrolyte and active site. Meanwhile, the introduction of polyvinylpyrrolidone (PVP) improved the hydrophilicity and dispersibility of N/NiCu@C, endowing superior electrocatalytic performance for IMI, THX and DNF determination, with linear ranges of 0.5-60, 1-60 and 0.5-60 µM, respectively, and detection limits of 0.017, 0.007 and 0.001 µM. Additionally, the sensor can determine IMI, THX and DNF in apples, tomatoes and potatoes with the recovery rate of 92.1-103.4% and RSD ≤ 4.7%. This study has explored a novel modified electrode material for construction of neonicotinoid sensors.

Highly selective and sensitive fluorescence detection of tetracyclines based on novel tungsten oxide quantum dots.

Tetracyclines (TCs) residues in animal products have attracted extensive concern due to their potential toxic to human health. Accordingly, it is urgent to develop an efficient method to determine TCs for providing consumers with risk pre-warning. Herein, a novel tungsten oxide quantum dots (WxOy QDs) fluorescence probe for tetracycline (TET) detection was constructed through ethanol-thermal method, which exhibited intense blue fluorescence under 365 nm UV light. Interestingly, blue-emitting WxOy QDs could be quenched obviously after the addition of TET, which may be attributed to the synergism of inner filter effect (IFE), fluorescence resonance energy transfer (FRET) and photo-induced electron transfer (PET). Thereby, the fluorescence method was established for TET detection based on WxOy QDs. Additionally, the presented method was demonstrated by monitoring TET in milk and milk powder with satisfactory recoveries. More importantly, this work offered good demonstration for the detection of food hazard factors.

Surface Selenylation Engineering for Construction of a Hierarchical NiSe2/Carbon Nanorod: A High-Performance Nonenzymatic Glucose Sensor.

As glucose (Glu) is an essential substance for metabolism as well as a symbol to diagnose diabetes, the demand of Glu sensors has increased significantly in recent decades. In this work, a hierarchical Ni-based electrochemical enzyme-free Glu sensor, namely, NiSe2/CNR (carbon nanorod), was engineered through a facile thermal treatment using dimethylglyoxime dinickel salt with selenium (Se) powder. The prepared NiSe2/CNR not only subtly introduces a hierarchical structure with rod-like carbon nanorods and rock-like NiSe2 nanoparticles, which are extremely helpful in offering a greater catalytic activity area and more catalytic active sites, but also incorporates the Se element to increase the inherent activity. The fabricated NiSe2/CNR exhibits distinguished performance for Glu detection in alkaline electrolytes with linear ranges of 0.5-411 µM and 411 µM to 6.311 mM, high sensitivities of 3636 µA mM-1 cm-2 at low concentrations, and 2121 µA mM-1 cm-2 at high concentrations, as well as a low detection limit of 380 nM (S/N = 3). It also possesses favorable reproducibility, stability, and long-term storage capacity. The practical feasibility of NiSe2/CNR was also validated by detecting Glu in human serum. Moreover, the prepared hierarchical NiSe2/CNR is of general interest for the construction of hierarchical Ni-based sensors.

Carbon cloth-supported nanorod-like conductive Ni/Co bimetal MOF: A stable and high-performance enzyme-free electrochemical sensor for determination of glucose in serum and beverage.

In this work, we propose a electrochemical enzyme-free glucose sensor by direct growth of conductive Ni/Co bimetal MOF on carbon cloth [Ni/Co(HHTP)MOF/CC] via a facile hydrothermal method. Due to excellent conductivity between Ni/Co(HHTP)MOF and CC, synergic catalytic effect of Ni and Co elements, the Ni/Co(HHTP)MOF/CC not only provides larger surface area and more effective active sites, but also boosts the charge transports and electro-catalytic performance. Under optimized conditions, the Ni/Co(HHTP)MOF/CC shows excellent activity with a linear range of 0.3 µM-2.312 mM, a low detection limit of 100 nM (S/N = 3), a fast response time of 2 s and a high sensitivity of 3250 µA mM-1 cm-2. Furthermore, the Ni/Co(HHTP)MOF/CC was successfully applied for the detection of glucose in real serum and beverages with competitive performances. This facile and cost-effective method provides a novel strategy for monitoring of glucose in biological and food samples.

Macro-meso-microporous carbon composite derived from hydrophilic metal-organic framework as high-performance electrochemical sensor for neonicotinoid determination.

Electrochemical analysis enables pesticides monitoring become rapid and efficient. Herein, novel three dimensional nitrogen-doped macro-meso-microporous carbon composites (N/Cu-HPC) derived from polyvinylpyrrolidone (PVP) doped Cu-metal organic framework were successfully formed via one-pot solvothermal method followed by pyrolysis, which were further applied in high-performance electrochemical determination of neonicotinoid. The introduction of PVP endows the N/Cu-HPC good hydrophilicity preventing aggregation as well as more highly electronegative nitrogen species boosting electro-catalytic property dramatically. Interestingly, the macro-meso-microporous architecture improves mass and charge transports between neonicotinoid molecules and active sites such as Cu nanoparticles and carbon atoms possessing Lewis basicity next to pyridinic-N. Based on the N/Cu-HPC, imidacloprid (IDP), thiamethoxam (THA) and dinotefuran (DNF) were detected with wide linear detection ranges (0.5-60 µM for both IDP and DNF, 1-60 µM for THA) and low detection limits (0.026 µM for IDP, 0.062 µM for THA and 0.01 µM for DNF). Meanwhile, this sensor can be successfully used for determination of IDP, THA and DNF in oat, corn and rice with good recoveries (92.0-100.9%, RSD ≤ 4.8%), demonstrating that the N/Cu-HPC possesses a high potential to be an advanced sensing device for monitoring neonicotinoid in agricultural products.

Rapid simultaneous adsorption and SERS detection of acid orange II using versatile gold nanoparticles decorated NH2-MIL-101(Cr).

Acid orange II (AO II), a typical azo pigment, is strictly controlled by legislation and prohibited in foodstuffs. Herein, we prepared gold nanoparticles decorated amino-functionalized Cr-based metal-organic frameworks [NH2-MIL-101(Cr)@Au] via an in-situ reduction method as a surface-enhanced Raman scattering (SERS) substrate for simultaneous adsorption and detection of AO II. Gold nanoparticles are uniformly dispersed on the surface of NH2-MIL-101(Cr) owing to its three-dimensional (3D) structure and the interaction between -NH2 and Au ions, providing more SERS-active "hot spots". These NH2-MIL-101(Cr)@Au nanocomposites exhibited selective and high adsorption performance (419.85 mg g-1) for AO II, and could be used as superior SERS substrates for the detection of AO II with a low limit of detection (LOD) of 0.05 mg L-1 and wide detection range of 0.05-50 mg L-1 using portable Raman spectrometer. Furthermore, this SERS assay has been successfully used to determine AO II in orange juice and chili powder with good sensitivities.