Photo-responsive hydrogels based on a ruthenium complex: synthesis and degradation.

We report the synthesis of a photo responsive metallo-hydrogel based on a ruthenium(II) complex as a functional cross-linker. This metal complex contains reactive 4AAMP (= 4-(acrylamidomethyl)pyridine) ligands, which can be cleaved by light-induced ligand substitution. Ru[(bpy)2(4AAMP)2] cross-links 4-arm-PEG-SH macromonomers by thia-Michael-addition to the photocleavable 4AAMP ligand for the preparation of the hydrogel. Irradiation with green light at 529 nm leads to photodegradation of the metallo-hydrogel due to the ligand dissociation, which can be adjusted by adjusting the Ru[(bpy)2(4AAMP)2] concentration. The ligand substitution forming [Ru(bpy)2(L)2]2+ (L = H2O and CH3CN) can be monitored by 1H NMR spectroscopy and UV-visible absorption. The control of degradation by light irradiation plays a significant role in modulating the elasticity and stiffness of the light sensitive metallo-hydrogel network. The photo-responsive hydrogel is a viable substrate for cell cultures.

Noble Metal Phosphides: Robust Electrocatalysts toward Hydrogen Evolution Reaction.

Facing with serious carbon emission issues, the production of green H2 from electrocatalytic hydrogen evolution reaction (HER) has received extensive research interest. Almost all kinds of noble metal phosphides (NMPs) consisting of Pt-group elements (i.e., Ru, Rh, Pd, Os, Ir and Pt) are all highly active and pH-universal electrocatalysts toward HER. In this review, the recent progress of NMP-based HER electrocatalysts is summarized. It is further take typical examples for discussing important impact factors on the HER performance of NMPs, including crystalline phase, morphology, noble metal element and doping. Moreover, the synthesis and HER application of hybrid catalysts consisting of NMPs and other materials such as transition metal phosphides, oxides, sulfides and phosphates, carbon materials and noble metals is also reviewed. Reducing the use of noble metal is the key idea for NMP-based hybrid electrocatalysts, while the expanded functionality and structure-performance relationship are also noticed in this part. At last, the potential opportunities and challenges for this kind of highly active catalyst is discussed.

Fluorescent nanocellulose-based hydrogel incorporating titanate nanofibers for sorption and detection of Cr(VI).

Chromium pollution is a major environmental concern; thus, effective and multifunctional adsorbents for removing the Cr(VI) ion are urgently needed. A fluorescent nanocellulose-based hydrogel (FNH) incorporating titanate nanofibers (TNs) was developed for the sorption and detection of Cr(VI) ion. The chemical and physical structures of the hydrogels, as well as their sorption and detection properties, were studied. The predicted maximum adsorption capacity and the lowest detection limit of FNH were 648.4 mg/g and 0.039 µg/L, respectively. Furthermore, the sorption and detection mechanisms of FNH were discussed in detail. These results showed that the excellent sorption and detection might be mainly attributed to the three-dimensional (3D) porous structure constructed by TNs and cellulose nanocrystals modified with carbon dots, which improved the sorption ability and provided the rapid visual response to Cr(VI). Furthermore, cost analysis showed that FNH was cheaper than activated carbon in removing the Cr(VI) ion. This work established a facile technique in developing low-cost and multifunctional adsorbents.

Chemical Approaches to Synthetic Drug Delivery Systems for Systemic Applications.

Poor water solubility and low bioavailability of active pharmaceutical ingredients (APIs) are major causes of friction in the pharmaceutical industry and represent a formidable hurdle for pharmaceutical drug development. Drug delivery remains the major challenge for the application of new small-molecule drugs as well as biopharmaceuticals. The three challenges for synthetic delivery systems are: (i) controlling drug distribution and clearance in the blood; (ii) solubilizing poorly water-soluble agents, and (iii) selectively targeting specific tissues. Although several polymer-based systems have addressed the first two demands and have been translated into clinical practice, no targeted synthetic drug delivery system has reached the market. This Review is designed to provide a background on the challenges and requirements for the design and translation of new polymer-based delivery systems. This report will focus on chemical approaches to drug delivery for systemic applications.

A nanoflower-like polypyrrole-based cobalt-nickel sulfide hybrid heterostructures with electrons migration to boost overall water splitting.

The development of high-efficiency and cost-effective difunctional electrocatalysts for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) are highly attractive to fulfill the practical water electrolysis. Herein, a novel low-cost difunctional cobalt-nickel sulfide (Co3S4/Ni3S2) flower-like heterostructures are purposely loaded on the surface of polypyrrole (PPy) nanosheets on nickel foam (NF) via feasible and efficient electrodeposition and hydrothermal tactics. The unique hierarchical architecture of the PPy nanosheets and strong electron interaction in the Co3S4/Ni3S2 nanohybrid effectively offer sufficient specific surface area and regulate electronic configuration for expediting the electrocatalytic process. The theoretical simulations also provide convincing proof that the interface of the Co3S4/Ni3S2 heterostructures supplies a lower energy pathway for water adsorption and dissociation, and the electrons migration that occurs when heterostructures emerge is probably the root of the result above. Consequently, the as-fabricated Co3S4/Ni3S2@PPy/NF exhibits outstanding electrochemical activity of HER and OER requiring low overpotentials of 63 mV and 207 mV to reach a current density of 10 mA cm-2 in the alkaline electrolyte, respectively. When equipped in a two-electrode electrolyzer, the Co3S4/Ni3S2@PPy/NF electrode couple displays a low voltage of only 1.52 V at 10 mA cm-2, indicating its potential application in the field of the water electrolysis.

Airflow ejection-wrapped clamping type seedling picking method and parameter optimization.

Since the current clamp-type and push-out-type seedling picking method brought damage to seedlings, this study aimed to proposed an airflow ejection-wrapped clamping type seedling picking method, which used airflow to eject out seedling and the seedlings were wrapped clamped to reduce the damage of seedlings during seedling picking process. The parameter model was established through theoretical design, then the parameters were optimized through coupling simulation analysis, and the validity of these parameters was verified through experiments. We found that the diameter of the airflow nozzle was selected as 3.5 mm to match with the drainage outlet of the plug tray, and the airflow pressure which could eject out seedlings was calculated as 0.146 Mpa~0.315 Mpa on the basis of gas jet dynamic. The fluid-solid coupling simulation of airflow ejection in Comsol proposed that the seedlings could be ejected out under the airflow pressure was equal to or greater than 0.4 Mpa, and the airflow should be maintained for about 0.3 s to ensure the posture of the seedlings ejected out for better seedling clamping. The further fluid-discrete body simulation of airflow ejection by using Fluent-Edem coupling method indicated that the seedling was damaged under airflow pressure of 0.5 MPa, so the airflow pressure should be set as 0.4 MPa during seedling ejection process. Besides, a wrapped clamping type effector which clamped the seedlings from all sides in the form of flexible package was also designed to match with the airflow ejection method, and the RecurDyn-Edem coupling simulation showed that the end-effector could tightly clamp the seedling without damage when the angle between the clamping slices and the vertical direction was 8.5°. Finally, the airflow ejection-wrapped clamping type seedling picking device was manufactured, and the verification tests verified the simulation results. This research can provide some references for the automatic seedling picking technology.

Highly sensitive detection of plant growth regulators by using terahertz time-domain spectroscopy combined with metamaterials.

The rapid and sensitive detection of plant-growth-regulator (PGR) residue is essential for ensuring food safety for consumers. However, there are many disadvantages in current approaches to detecting PGR residue. In this paper, we demonstrate a highly sensitive PGR detection method by using terahertz time-domain spectroscopy combined with metamaterials. We propose a double formant metamaterial resonator based on a split-ring structure with titanium-gold nanostructure. The metamaterial resonator is a split-ring structure composed of a titanium-gold nanostructure based on polyimide film as the substrate. Also, terahertz spectral response and electric field distribution of metamaterials under different analyte thickness and refractive index were investigated. The simulation results showed that the theoretical sensitivity of resonance peak 1 and peak 2 of the refractive index sensor based on our designed metamaterial resonator approaches 780 and 720 gigahertz per refractive index unit (GHz/RIU), respectively. In experiments, a rapid solution analysis platform based on the double formant metamaterial resonator was set up and PGR residues in aqueous solution were directly and rapidly detected through terahertz time-domain spectroscopy. The results showed that metamaterials can successfully detect butylhydrazine and N-N diglycine at a concentration as low as 0.05 mg/L. This study paves a new way for sensitive, rapid, low-cost detection of PGRs. It also means that the double formant metamaterial resonator has significant potential for other applications in terahertz sensing.

Toolbox of Biodegradable Dendritic (Poly glycerol sulfate)-SS-poly(ester) Micelles for Cancer Treatment: Stability, Drug Release, and Tumor Targeting.

In this paper, we present well-defined dPGS-SS-PCL/PLGA/PLA micellar systems demonstrating excellent capabilities as a drug delivery platform in light of high stability and precise in vitro and in vivo drug release combined with active targetability to tumors. These six amphiphilic block copolymers were each targeted in two different molecular weights (8 or 16 kDa) and characterized using 1H NMR, gel permeation chromatography (GPC), and elemental analysis. The block copolymer micelles showed monodispersed size distributions of 81-187 nm, strong negative charges between -52 and -41 mV, and low critical micelle concentrations (CMCs) of up to 1.13-3.58 mg/L (134-527 nM). The serum stability was determined as 94% after 24 h. The drug-loading efficiency for Sunitinib ranges from 38 to 83% (8-17 wt %). The release was selectively triggered by glutathione (GSH) and lipase, reaching 85% after 5 days, while only 20% leaching was observed under physiological conditions. Both the in vitro and in vivo studies showed sustained release of Sunitinib over 1 week. CCK-8 assays on HeLa lines demonstrated the high cell compatibility (1 mg/mL, 94% cell viability, 48 h) and the high cancer cell toxicity of Sunitinib-loaded micelles (IC50 2.5 µg/mL). By in vivo fluorescence imaging studies on HT-29 tumor-bearing mice, the targetability of dPGS7.8-SS-PCL7.8 enabled substantial accumulation in tumor tissue compared to nonsulfated dPG3.9-SS-PCL7.8. As a proof of concept, Sunitinib-loaded dPGS-SS-poly(ester) micelles improved the antitumor efficacy of the chemotherapeutic. A tenfold lower dosage of loaded Sunitinib led to an even higher tumor growth inhibition compared to the free drug, as demonstrated in a HeLa human cervical tumor-bearing mice model. No toxicity for the organism was observed, confirming the good biocompatibility of the system.

A study of plant growth regulators detection based on terahertz time-domain spectroscopy and density functional theory.

Terahertz technology is receiving increasing attention for its use as an efficient non-destructive, non-contact and label-free optical method for qualitative and quantitative detection. The aim of this study was to develop a chemical analysis methodology based on terahertz time-domain spectra that could be used to detect plant growth regulators, such as glyphosine, naphthaleneacetic acid, daminozide and gibberellic acid. The THz fingerprint spectra of these four PGRs were located in the 0.3-1.8 THz, with the peaks of glyphosine at 0.32, 0.49, 0.74, 0.87, 0.96, and 1.49 THz; daminozide at 0.33, 0.39, 0.55, 0.67, and 1.17 THz; gibberellic acid at 0.46, 0.58, 0.92, and 1.38 THz and naphthaleneacetic acid at 0.43, 0.57, 0.73, and 0.90 THz. The results showed that these four plant growth regulators exhibited numerous distinct spectral features in frequency-dependent absorption spectra, which demonstrated the qualitative capacity of terahertz time-domain. The origin of the observed terahertz absorption peaks of these four plant growth regulators was determined through density functional theory calculations and analysis of absorption spectra. Discriminant analysis method was used to evaluate the classification trends of the four plant growth regulators based on their THz absorbance spectra. Generally, this study provides a reference for the rapid detection of plant growth regulators in fruits and vegetables by using terahertz spectroscopy technology.

[Quantitative determination of imidacloprid by infrared absorption spectrometry].

The content of imidacloprid in pesticide is usually measured by high-performance liquid chromatography, which is precise but time-consuming. In the present work the content of imidacloprid in pesticide was measured by infrared spectroscopy with pressing potassium bromide troche (KBr). A comparison of infrared spectra between analytic imidacloprid and commercial pesticide showed that the absorption peak of imidacloprid at 939.2 cm(-1) is independent and can be used as the characteristic absorption peak for quantitative determination. The area from 947 to 925.8 cm(-1) for the infrared spectra of imidacloprid and its content meet the linear equation: Area = l.3665 x 10(-1) + 2.37 x 10(-2) x c, r = 0.99953. Finally, the authors could draw a conclusion that the method of NIR, instead of routine lab analysis, is feasible for the determination of imidacloprid in pesticide.

[Spectroscopy research on the origin mechanism for light induced delayed fluorescence of chloroplast].

Research of the mechanism for delayed fluorescence origin play an important role in the application of DF. Based onthe charge recombination theory, the mechanism for delayed fluorescence origin is theoretically analyzed in this paper. The decay kinetics of DF, depending on the backward transport electron and oxidized state P680+, can be well fitted by poly-exponent. The relative fast component of DF originates from the Z+ P680 Q(A)- states, generated during the previous period of the sample illumination. On the other hand, the slow component of DF is ascribed to the state Q(B)= --the next electron carrier of deoxidized side in PS II. Meanwhile, the experimental results confirmed the theoretical conclusion. Furthermore, the authors testified that the third component with lifetime much greater than the time of the registration period (which is presented as a constant), is corresponds to the recombination of P680+ and the backward transport electron from PSI.

[Preoperative hyperfractionated accelerated irradiation-induced apoptosis in non-small cell lung cancer].

BACKGROUND: To study the apoptosis inducing effect of preoperative hyperfractionated accelerated radiation therapy (HART) and expression of Bcl-2, Bax proteins in non-small cell lung cancer. METHODS: From October 1999 to March 2001, 81 patients with non-small cell lung cancer were prospectively divided into preoperative HART group (20 patients) and surgical group (61 patients). The patients in preoperative HART group were given preoperative irradiation with 2.5 Gy/fraction, twice a day to a total dose of 25 Gy/10 fractions/5-7 days using anterior-posterior opposing parallel fields, then operation would be performed within 2 weeks. The patients in surgical group only received surgical treatment. Apoptotic index (AI), cell cycle distribution and expression of Bcl-2, Bax proteins were quantitatively analyzed by indirect-immunofluorescene and flow cytometry. RESULTS: AI was 4.6%±2.3% in surgical group and 12.8%±4.3% in preoperative HART group, respectively ( P < 0.001). There was no difference in S phase fraction (SPF) between the two groups ( P > 0.05). The fluorescence index (FI) for Bcl-2, Bax proteins and the ratio of Bcl-2/Bax were 1.33±0.21, 1.05±0.13 and 1.29±0.23 in surgical group, and 1.14±0.26, 1.19±0.16 and 0.96±0.23 in preoperative HART group respectively ( P < 0.01, P < 0.001 and P < 0.001 respectively). AI showed a positive correlation to Bax protein ( P < 0.001) and a negative correlation to the ratio of Bcl-2/Bax ( P < 0.01). CONCLUSIONS: Preoperative HART may induce a high-level apoptosis by decreasing the expression of Bcl-2 protein and increasing the expression of Bax protein. However, it is still necessary to further observe whether it can improve the long-term survival of patients with NSCLC.