Calcium carbonate: controlled synthesis, surface functionalization, and nanostructured materials.

Calcium carbonate (CaCO3) is an important inorganic mineral in biological and geological systems. Traditionally, it is widely used in plastics, papermaking, ink, building materials, textiles, cosmetics, and food. Over the last decade, there has been rapid development in the controlled synthesis and surface modification of CaCO3, the stabilization of amorphous CaCO3 (ACC), and CaCO3-based nanostructured materials. In this review, the controlled synthesis of CaCO3 is first examined, including Ca2+-CO32- systems, solid-liquid-gas carbonation, water-in-oil reverse emulsions, and biomineralization. Advancing insights into the nucleation and crystallization of CaCO3 have led to the development of efficient routes towards the controlled synthesis of CaCO3 with specific sizes, morphologies, and polymorphs. Recently-developed surface modification methods of CaCO3 include organic and inorganic modifications, as well as intensified surface reactions. The resultant CaCO3 can then be further engineered via template-induced biomineralization and layer-by-layer assembly into porous, hollow, or core-shell organic-inorganic nanocomposites. The introduction of CaCO3 into nanostructured materials has led to a significant improvement in the mechanical, optical, magnetic, and catalytic properties of such materials, with the resultant CaCO3-based nanostructured materials showing great potential for use in biomaterials and biomedicine, environmental remediation, and energy production and storage. The influences that the preparation conditions and additives have on ACC preparation and stabilization are also discussed. Studies indicate that ACC can be used to construct environmentally-friendly hybrid films, supramolecular hydrogels, and drug vehicles. Finally, the existing challenges and future directions of the controlled synthesis and functionalization of CaCO3 and its expanding applications are highlighted.

Intrinsic Blue Fluorescence of 2.0G PAMAM-DCM Polymer Dots and Its Applications for Fe3+ Sensing.

A typical and environment-friendly fluorescent polyamine-amine (PAMAM) features good compatibility and unique surface modification, while it is restricted by a low fluorescence property performance and an unclear fluorescence mechanism. In this work, we prepared blue fluorescent PAMAM polymer dots (PDs) via a simple hydrothermal method based on dichloromethane (DCM) and 2.0G PAMAM. The quantum yield achieved was 32.1%, which was 25 times stronger than that of 2.0G PAMAM due to the lone-pair electron leap of the amine groups, the aggregation of carbonyl groups, as well as the crosslinking induced by DCM inside the PAMAM. In addition, the fluorescent 2.0G PAMAM-DCM PDs show a great Fe3+ sensing property with the detection limit of 56.6 nM, which is much lower than the safety limits (5.36 µM) in drinking water, indicating its great potential for Fe3+ detection in aqueous media.

Micromorphological characterization and label-free quantitation of small rubber particle protein in natural rubber latex.

Commercial natural rubber is traditionally supplied by Hevea brasiliensis, but now there is a big energy problem because of the limited resource and increasing demand. Intensive study of key rubber-related substances is urgently needed for further research of in vitro biosynthesis of natural rubber. Natural rubber is biosynthesized on the surface of rubber particles. A membrane protein called small rubber particle protein (SRPP) is a key protein associated closely with rubber biosynthesis; however, SRPP in different plants has been only qualitatively studied, and there are no quantitative reports so far. In this work, H. brasiliensis was chosen as a model plant. The microscopic distribution of SRPP on the rubber particles during the washing process was investigated by transmission electron microscopy-immunogold labeling. A label-free surface plasmon resonance (SPR) immunosensor was developed to quantify SRPP in H. brasiliensis for the first time. The immunosensor was then used to rapidly detect and analyze SRPP in dandelions and prickly lettuce latex samples. The label-free SPR immunosensor can be a desirable tool for rapid quantitation of the membrane protein SRPP, with excellent assay efficiency, high sensitivity, and high specificity. The method lays the foundation for further study of the functional relationship between SRPP and natural rubber content.

Peroxidase in plant defense: Novel insights for cadmium accumulation in rice (Oryza sativa L.).

Phenylpropanoid biosynthesis plays crucial roles in the adaptation to cadmium (Cd) stress. Nevertheless, few reports have dabbled in physiological mechanisms of such super pathway regulating Cd accumulation in plants. Herein, by integrating transcriptomic, histological and molecular biology approaches, the present study dedicated to clarify molecular mechanism on how rice adapt to Cd stress via phenylpropanoid biosynthesis. Our analysis identified that the enhancement of phenylpropanoid biosynthesis was as a key response to Cd stress. Intriguingly, POD occupied a significant part in this process, with the number of POD related genes accounted for 26/29 of all upregulated genes in phenylpropanoid biosynthesis. We further used SHAM (salicylhydroxamic acid, the POD inhibitor) to validate that POD exhibited a negative correlation with the Cd accumulation in rice tissues, and proposed two intrinsic molecular mechanisms on POD in contributing to Cd detoxification. One strategy was that POD promoted the formation of lignin and CSs both in endodermis and exodermis for intercepting Cd influx. In detail, inhibited POD induced by external addition of SHAM decreased the content of lignin by 50.98-66.65 % and delayed percentage of the DTIP-CS to root length by 39.17-104.51 %. The other strategy was expression of transporter genes involved in Cd uptake, including OsIRT1, OsIRT2, OsZIP1 and OsZIP, negatively regulated by POD. In a word, our findings firstly draws a direct link between POD activity and the Cd accumulation, which is imperative for the breeding of rice with low-Cd-accumulating capacity in the future.

Water-resistant and pyknotic recyclable waste-cotton-derived bio-polyurethane-coated controlled-release fertilizer: Improved longevity, mechanism and application.

Reasonably utilize the recyclable waste-cotton resource to develop the bio-polyurethane coatings had aroused more and more environmental interests recently. However, the terrible water resistance and porousness of the waste-cotton-derived bio-polyurethane coating caused the rapid nutrients release. In this work, the water-resistant and pyknotic cotton-fibre-derived coated-ureas (WPCUs) were fabricated with the recyclable low-cost waste-cotton-derived materials. The dramatically enhanced pyknotic and water-resistant characteristics of the WPCUs coatings can be obtained by the three-dimensional computerized tomography (2.33 to 1.19 %) and the water contact angle. The enhanced elasticity and the decreased water absorption were also vital to enhance the controlled-release performance. The accompanying controlled-release performance of the WPCUs was obviously improved (<2 h to 58.43 days). The modified WPCU75-10 with 4.0 % coating content exhibits the excellent controlled-release performance compared to the unmodified WPCU0-0. The controlled release mechanism can be clarified: The air column inside of the "small and few" micropores in the WPCUs coating only allow the gaseous water molecules to slowly penetrate and dissolve the inner urea cores (rather than liquid water). The obviously increased oilseed rape yield (128.75 %) showed the dependable agricultural application of the WPCUs. This work provides the resultful approach to develop the eco-friendly recyclable waste-plant-derived controlled-release fertilizers.

Molecular characteristics and phylogenetic analysis of N gene of human derived rabies virus.

OBJECTIVE: To investigate the relationship between the molecular characteristics and phylogenetic evolution of rabies N gene. METHODS: Saliva samples were collected from rabies cases, and RT-PCR was used to amplify the N gene of rabies virus with the specific primers. The amplifying product of RT-PCR was cloned to pUCm-T vector and transformed into E.coli XL1-Blue and then the blue-white selection, PCR screening and gene sequencing were carried out to identify the positive clones. Finally, ExPASy and other bioinformatics software were used to analyze and predict the structure and biological characteristics of the N genome. RESULTS: The amplification product of RT-PCR was 1 353 bp, the recombinant plasmid pUCm-T/N was constructed, the whole length of the N gene open reading frame was composed of 1 353 nucleotide residues to code 450 amino acids (20 kinds), the accession number submitted to the Genbank was HM756692, its sequence homology of nucleotides and amino acids compared with the vaccine strain CTN-1-V was 90% and 99% respectively. The evolutionary analysis showed that the isolated strain belonged to genotype I with certain geographic regionality. CONCLUSION: The characteristics investigation and bioinformatics analysis of Hunan0806 N gene will provide fundamental data to reveal the significance of the N gene characteristics for rabies epidemiology and its prevention & control.

131I-radioisotope modified in PEGylation metal organic frameworks for sensitization in refractory differentiated thyroid cancer treatment.

Radiation therapy for cancer can lead to off-target toxicity and can be ineffective against refractory differentiated thyroid cancer. The nanoscale metal organic frameworks (NMOFs) have shown great potential in cancer diagnostic and treatment due to their advantages in the aspect of structural diversities, high intrinsic biodegradability and drug-loading capacities. Here, we provide that intratumoral injection, in mouse of refractory differentiated thyroid cancer.In this work, we used the therapeutic 131I radioisotope modified Zr-MOF (Zr-MOF@131I) with aim to enable long-term relief of tumour therapy, which has successfully eliminated tumour at ralatively low radioactivity doses. Polyethylene glycol (PEG) was coated into Zr-MOF and, as a result, circulation time was significantly improved by intratumoral injection. These findings therefore suggest that nanoparticles could be used in vivo combined therapy. On injection, while it is a highly effective drug for radioisotope, Zr-MOF with attenuation ability could apply for a radio-sensitizer to enhance inner radiotherapy (RT). The local therapy, which uses only biocompatible components, might enable new strategies for local tumour treatments. These could be further combined with systemic therapeutic responses for the inhibition of refractory differentiated thyroid cancer and the prevention of tumour recurrence in patients.

Multiplex amplification of target genes of periodontal pathogens in continuous flow PCR microfluidic chip.

Porphyromonas gingivalis (P.g), Treponema denticola (T.d), and Tannerella forsythia (T.f) are believed to be the major periodontal pathogens that cause gingivitis, which affects 50-90% of adults worldwide. Microfluidic chips based on continuous flow PCR (CF-PCR) are an ideal alternative to a traditional thermal cycler, because it can effectively reduce the time needed for temperature transformation. Herein, we explored multi-PCR of P.g, T.d and T.f using a CF-PCR microfluidic chip for the first time. Through a series of experiments, we obtained two optimal combinations of primers that are suitable for performing multi-PCR on these three periodontal pathogens, with amplicon sizes of (197 bp, 316 bp, 226 bp) and (197 bp, 316 bp, 641 bp), respectively. The results also demonstrated that by using multi-PCR, the amplification time can be reduced to as short as 3'48'' for the short-sized amplicons, while for T.f (641 bp), the minimum time required was 8'25''. This work provides an effective way to simultaneously amplify the target genes of P.g, T.d and T.f within a short time, and may promote CF-PCR as a practical tool for point-of-care testing of gingivitis.

Mixed-Halide Perovskite Film-Based Neuromorphic Phototransistors for Mimicking Experience-History-Dependent Sensory Adaptation.

Sensory adaptation is an essential function for humans to live on the earth. Herein, a hybrid synaptic phototransistor based on the mixed-halide perovskite/organic semiconductor film is reported. This hybrid phototransistor achieves photosensitive performance including a high photoresponsivity over 4 × 103 A/W and an excellent specific detectivity of 2.8 × 1016 Jones. Due to the photoinduced halide-ion segregation of the mixed-halide perovskites and their slow recovery properties, the experience-history-dependent sensory adaptation behavior can be mimicked. Moreover, the light pulse width, intensity, light wavelength, and gate bias can be used to regulate the adaptation processes to improve its adaptability and perceptibility in different environments. The CsPbBrxI3-x/organic semiconductor hybrid films produced by spin coating are beneficial to large-scale fabrication. This study fabricates a novel solution-processable light-stimulated synapse based on inorganic perovskites for mimicking the human sensory adaptation that makes it possible to approach artificial neural sensory systems.

Development of Lateral Flow Immunochromatographic Strips for Micropollutants Screening Using Colorants of Aptamer Functionalized Nanogold Particles Part I Methodology and Optimization.

A methodology of lateral flow immunochromatographic strip based on aptamer was developed for on-site detection of the small molecule micropollutants. In the present study, we try for the first time to investigate the feasibility of developing a strip assay for the analysis of micropollutants as methodological prototypes by combining the high selectivity and affinity of aptamers with the unique optical properties of nanogolds. This quantitative method was based on the competition for the aptamer between targets and DNA probes. Crucial parameters that might influence the sensitivity, such as the size of nanogolds, amount of aptamer, type and pH of streptavidin, type of nitrocellulose (NC) membrane, blocking procedure, and reading time, were systematically investigated to obtain the optimum assay performance. With the optimized conditions [nanogolds 25 nm, 50 µM aptamer, pH 8 of GSA (a type of streptavidin named "SA Gold," which is a sulfhydrylization streptavidin), Millipore HFC 135 NC membrane, 1% bovine serum albumin as the blocking agent and added in the running buffer and sample pad soakage agents, and 20 min reading time] the aptamer-based lateral flow assay will show a low visual limit of detection and scanning reader LOD. The strip for on-site screening using colorants of aptamer functionalized nanogold particles did not require any complicated equipment and was a potential portable tool for rapid identification of micropollutants.

Blood Clearance, Distribution, Transformation, Excretion, and Toxicity of Near-Infrared Quantum Dots Ag2Se in Mice.

As a novel fluorescent probe in the second near-infrared window, Ag2Se quantum dots (QDs) exhibit great prospect in in vivo imaging due to their maximal penetration depth and negligible background. However, the in vivo behavior and toxicity of Ag2Se QDs still largely remain unknown, which severely hinders their wide-ranging biomedical applications. Herein, we systematically studied the blood clearance, distribution, transformation, excretion, and toxicity of polyethylene glycol (PEG) coated Ag2Se QDs in mice after intravenous administration with a high dose of 8 µmol/kg body weight. QDs are quickly cleared from the blood with a circulation half-life of 0.4 h. QDs mainly accumulate in liver and spleen and are remarkably transformed into Ag and Se within 1 week. Ag is excreted from the body readily through both feces and urine, whereas Se is excreted hardly. The toxicological evaluations demonstrate that there is no overt acute toxicity of Ag2Se QDs to mice. Moreover, in regard to the in vivo stability problem of Ag2Se QDs, the biotransformation and its related metabolism are intensively discussed, and some promising coating means for Ag2Se QDs to avert transformation are proposed as well. Our work lays a solid foundation for safe applications of Ag2Se QDs in bioimaging in the future.

Simultaneous qualitation and quantitation of natural trans-1,4-polyisoprene from Eucommia ulmoides Oliver by gel permeation chromatography (GPC).

Natural trans-1,4-polyisoprene (TPI) as a functional biomaterial has aroused great interest for rubber industrial product use. Here, we proposed a method that enables simultaneous analysis of the content and molecular-weight distribution (MWD) of natural TPI by gel permeation chromatography (GPC). The natural TPIs were collected from leaves, fruit coatings and bark of Eucommia ulmoides Oliver (E. ulmoides) through toluene extraction followed by ethanol purification. The results of TPI contents from leaves and fruit coatings were shown ca. 3.5% and 13.8%, respectively. Accordingly, limits of detection (LODs) of TPI were 0.58mg/mL from leaves and 0.47mg/mL from fruit coatings. The MWDs of TPI demonstrated a bimodal distribution from leaves, a unimodal distribution from bark, and a unimodal distribution with a tiny peak shoulder from fruit coatings. In real-life E. ulmoides analysis, the results from three independent methods (GPC, gravimetric method, and infrared spectroscopy) were obtained with good consistency.

In vitro toxicity evaluation of graphene oxide on A549 cells.

Graphene and its derivatives have attracted great research interest for their potential applications in electronics, energy, materials and biomedical areas. However, little information of their toxicity and biocompatibility is available. Herein, we performed a comprehensive study on the toxicity of graphene oxide (GO) by examining the influences of GO on the morphology, viability, mortality and membrane integrity of A549 cells. The results suggest that GO does not enter A549 cell and has no obvious cytotoxicity. But GO can cause a dose-dependent oxidative stress in cell and induce a slight loss of cell viability at high concentration. These effects are dose and size related, and should be considered in the development of bio-applications of GO. Overall, GO is a pretty safe material at cellular level, which is confirmed by the favorable cell growth on GO film.