Stimuli-responsive and self-healing supramolecular Zn(II)-guanosine metal-organic gel for Schottky barrier diode application.

Spontaneous formation of a supramolecular metal-organic hydrogel using unsubstituted guanosine as a ligand and Zn2+ ions is reported. Guanosine, in the presence of NaOH, self-assembled into a stable G-quadruplex structure, which underwent crosslinking through Zn2+ ions to afford a stable hydrogel. The gel has been characterized using several spectroscopic as well as microscopic studies. The hydrogel demonstrated excellent stimuli responsiveness towards various chemicals and pH. Furthermore, the gel exhibited intrinsic thixotropic behavior and showed self-healing and injectable properties. The optical properties of the Zn-guanosine metallo-hydrogel suggested a semiconducting nature of the gel, which has been exploited for fabricating a thin film device based on a Schottky diode interface between metal and a semiconductor. The fabricated device shows excellent charge transport characteristics and linear rectifying behavior. The findings are likely to pave the way for newer research in the area of soft electronic devices fabricated using materials synthesized by employing simple biomolecules.

Cobalt-Adenosine Monophosphate Supramolecular Hydrogel with pH-Responsive Multi-Nanozymatic Activity.

Self-assembled metal-ion cross-linked multifunctional hydrogels are gaining a lot of attention in the fields of biomedical and biocatalysis. Herein, we report a heat-triggered metallogel that was spontaneously formed by the self-assembly of adenosine 5'-monophosphate (AMP) and cobalt chloride, accompanied by a color transition depicting an octahedral to tetrahedral transition at high temperature. The hydrogel shows excellent stability in a wide pH window from 1 to 12. The metallogel is being exploited as a multienzyme mimic, exhibiting pH-responsive catalase and peroxidase activity. Whereas catalase mimicking activity was demonstrated by the hydrogel under neutral and basic conditions, it shows peroxidase mimicking activity in an acidic medium. The multifunctionality of the synthesized metallogel was further demonstrated by phenoxazinone synthase-like activities. Owing to its catalase-mimicking activity, the metallogel could effectively reduce the oxidative stress produced in cells due to excess hydrogen peroxide by degrading H2O2 to O2 and H2O under physiological conditions. The biocompatible metallogel could prevent cell apoptosis by scavenging reactive oxygen species. A green and simple synthetic strategy utilizing commonly available biomolecules makes this metallogel highly attractive for catalytic and biomedical applications.

A comparative study of variable angle volar plate and bridging external fixator with K-wire augmentation in comminuted distal radius fractures.

PURPOSE: Comminuted intraarticular distal radial fractures are difficult to treat conservatively and require operative treatment. This study compared the functional outcomes between variable angle volar plating and external fixator with K-wire augmentation in open reduction and internal fixation. METHODS: A total of 62 adult patients with comminuted intraarticular distal radius fracture were randomized into 2 groups: volar plate group and external fixator group. These patients aged between 18 and 60 years had unilateral fractures, and agreed to be included in the study. Patients with a history of fracture, bilateral fracture, associated other injuries, delayed injury for more than 2 weeks, open fracture, pre-existing arthrosis or disability, psychiatric illness and pathological fracture were excluded. Patients were followed up at 6 weeks, 3 months, 6 months and 1 year. The assessment of pain, functional activity, range of motion and grip strength was done at each stage of follow-up. The pain and functional activities were assessed by patient rated wrist evaluation (PRWE) score and disabilities of the arm, shoulder and hand (DASH) score. RESULTS: Patients in volar plate group had superior PRWE score and DASH score at each stage of follow-up. At 1 year follow-up, the mean PRWE score were 7.48 for volar plate group and 7.35 for external fixator group; while the mean DASH score was 4.65 for volar plate group and 5.61 for external fixator group. They had better flexion and extension range of movement. They also had better pronation and supination range of motion at initial follow-up, however the difference get attenuated by 1 year. Volar plate group had significantly better grip strength than external fixator group. Complication rates were higher in external fixation group. CONCLUSION: Fixation with variable angle volar plate results in early wrist mobilization, better range of movement, less pain and disability and early return of function.

Biocompatible Fe3+ and Ca2+ Dual Cross-Linked G-Quadruplex Hydrogels as Effective Drug Delivery System for pH-Responsive Sustained Zero-Order Release of Doxorubicin.

The ultimate aim in developing controlled drug delivery systems is to derive formulations to achieve drug release at a constant rate over a long duration. The drug release profile that follows zero-order kinetics is crucial for reduction in the drug administration frequency, reduced cytotoxicity, and improved convenience and compliance of patients. Designed drug delivery systems for achieving zero-order release are often complex, expensive, and difficult to manufacture. Herein, we demonstrate that a supramolecular hydrogel formed through the self-assembly of guanosine monophosphate (GMP) into highly ordered G-quadruplex structure and cross-linked through Fe3+ and Ca2+ ions exhibits potential for the pH-responsive controlled zero-order drug release of doxorubicin, a model chemotherapeutic drug. The fibril formation is initiated by the self-assembly of GMP into a quadruplex complex, which is cross-linked through the complexation of the phosphate groups with Fe(III) ions, resulting in a spontaneous hydrogel formation. The Ca2+ ions facilitate the improvement in the mechanical integrity of the fibril network in the Fe-GMP hydrogel via cross-linking of sugar moieties. The hydrogel showed a high loading capacity for drug molecules and a pH-responsive sustained zero-order drug release over several days owing to the lowered degradability of the cross-linked hydrogel in acidic buffer stimulant. In vitro drug-release studies further established a controlled pH-triggered drug release profile. The Ca2+ cross-linking of the Fe-GMP hydrogel also resulted in significant enhancement in the biocompatibility of the drug delivery system. The fabrication of biocompatible, low-cost, and efficient Ca2+ cross-linked metal-organic hydrogels may present promising applications in biological fields.

White light emission from a mixture of silicon quantum dots and gold nanoclusters and its utilities in sensing of mercury(ii) ions and thiol containing amino acid.

White light emitting mixture (WLEM) was produced by controlled mixing of blue emitting silicon quantum dots (Si QDs) and orange red emitting gold nanoclusters (Au NCs). The chromaticity color co-ordinate of the WLEM studied using CIE (Commission Internationale del'Eclairage) diagram was found to be (0.33, 0.32), which was very close to that of perfect white light emitting source. The WLEM can also be achieved in the form of gel, solid and film with nearly the same CIE co-ordinates which enhances its utility as white light-emitting source in solid state devices. The reversible and thermo-responsive behaviour of the WLEM broadens its application in thermal sensing. Furthermore, the system was found to be showing fast, sensitive and selective detection of Hg2+ ions and thiol containing amino acid cysteine.

Cd(ii)-nucleobase supramolecular metallo-hydrogels for in situ growth of color tunable CdS quantum dots.

The integration of nanoscale materials into unconventional environments such as gels is a magnificent strategy towards development of engineered hybrid functional systems. Herein, the in situ formation of CdS quantum dots integrated into a metallogel formed through the coordination of Cd2+ with two pyrimidine nucleobases is reported. Thymine and uracil formed spontaneous hydrogels with nanofibrous morphology through coordinative interaction with Cd2+ ions at alkaline pH. Introduction of Na2S resulted in generation of CdS quantum dots within the hydrogels with tunable emission properties from blue to white to yellow. The quenching of emission of white light system was exploited for the sensing of Fe3+ and Cu2+ ions. Such a color tunable quantum dot incorporated metallogel system will find applications in energy harvesting and sensing.

Carbon Dots as Nanodispersants for Multiwalled Carbon Nanotubes: Reduced Cytotoxicity and Metal Nanoparticle Functionalization.

The colloidal stabilization of multiwalled carbon nanotubes (MWCNTs) in an aqueous medium through noncovalent interactions has potential benefits toward the practical use of this one-dimensional carbonaceous material for biomedical applications. Here, we report that fluorescent carbon nanodots can efficiently function as dispersing agents in the preparation of stable aqueous suspensions of CNTs at significant concentrations (0.5 mg/mL). The amphiphilic nature of carbon dots with a hydrophobic graphitic core could effectively interact with the CNT surface, whereas hydrophilic oxygenated functionalization on the C-dot surface provided excellent water dispersibility. The resultant CNT-C-dot composite showed significantly reduced cytotoxicity compared to that of unmodified or protein-coated CNTs, as demonstrated by cell viability and proliferation assays. Furthermore, the reducing capability of C-dots could be envisaged toward the formation of a catalytically active metal nanoparticle-CNT-C-dot composite without the addition of any external reducing or stabilizing agents that showed excellent catalytic activity toward the reduction of p-nitrophenol in the presence of NaBH4. Overall, the present work establishes C-dots as an efficient stabilizer for aqueous dispersions of CNTs, leading to an all-carbon nanocomposite that can be useful for different practical applications.

Susceptibility of Rubella Among Pregnant Women Attending the Antenatal Clinic in a Tertiary Care Hospital, Jabalpur, Central India.

The purpose of this study was to evaluate rubella susceptibility of pregnant women from central India as rubella infection can be devastating for the newborn if it occurs in the mother in the first trimester of pregnancy, which may lead to congenital rubella syndrome (CRS). There are very few studies about seroprevalence of rubella from India and none from central India. The study was conducted among women attending the obstetric department of a tertiary care hospital, in which 369 antenatal cases were tested for the presence of immunoglobulin G antibody for rubella and its titer. Data were analyzed using statistical tests. A total of 141 (38.2%) women were found susceptible to rubella. There was no significant difference in rubella susceptibility among different socioeconomic classes, ages, and gravidity. A large proportion of pregnant women were found to be rubella susceptible, posing immense threat of CRS to their newborns. A robust program for rubella immunization targeting young adult women is needed to avoid CRS.

Carbon nanodots as ligand exchange probes in Au@C-dot nanobeacons for fluorescent turn-on detection of biothiols.

Au nanoparticle-carbon dot core-shell (Au@C-dot) nanocomposite was synthesized in aqueous medium at room temperature using the carbon dots as reducing agents themselves. The carbon nanodots also function as an effective stabilizer by forming a thin layer surrounding Au nanoparticles (Au NPs) similar to self-assembled monolayers. Ligand exchange with thiol containing biomolecules resulted in the release of carbon dots from the Au NP surface leading to an enhancement of fluorescence. Simultaneously the agglomeration of Au NPs stimulated by the interaction of biothiols led to changes in the surface plasmon properties of Au NPs. A detailed spectroscopic investigation revealed a combination of static and dynamic quenching being involved in the process. Thus, the Au nanoparticle-carbon dot composite could be used as a dual colorimetric and fluorometric sensor for biothiols ranging from amino acids, peptides, proteins, enzymes etc. with a detection limit of 50 nM.

Development and characterization of a cell line WAF from freshwater shark Wallago attu.

A new epithelial cell line, WAF was developed from caudal fin of freshwater shark, Wallago attu. The cell line was optimally maintained at 28 °C in Leibovitz-15 (L-15) medium supplemented with 20 % fetal bovine serum. The cell line was characterized by various cytogenetic and molecular markers. The cytogenetic analysis revealed a diploid count of 86 chromosomes at different passages. The origin of the cell lines was confirmed by the amplification of 547 and 654 bp sequences of 16S rRNA and cytochrome oxidase subunit I genes of mitochondrial DNA, respectively. WAF cells were characterized for their growth characteristics at different temperature and serum concentration. Epithelial morphology of the cell line was confirmed using immunocytochemistry. Further cell plating efficiency, transfection efficiency and viability of cryopreserved WAF cells was also determined. Cytotoxicity and genotoxicity assessment of cadmium salts on WAF cells by MTT, NR and comet assay illustrated the utility of this cell line as an in vitro model for aquatic toxicological studies. The cell line will be further useful for studying oxidative stress markers against aquatic pollutants.

In vitro cytotoxicity assessment of two heavy metal salts in a fish cell line (RF).

Labeo rohita (rohu) is one of most important of Indian major carps, which is highly ranked among the important freshwater aquaculture species in the world. Heavy metals are major risk factors for aquatic health, which are biomagnified through the food chain. The present study was carried out to investigate the effect of different divalent salts of two heavy metals, such as zinc (ZnCl(2), ZnSO(4) and ZnNO(3)) and cadmium (CdCl(2) and CdSO(4)), in an established fish cell line, RF developed from fin tissue of L. rohita. The RF cell line was used for assessment of heavy metal cytotoxicity through various endpoint assays, including maximum tolerated dose (MTD) determination, 3-[4,5-dimethylthiazole-2-yl]-2,5-diphenyl tetrazolium bromide (MTT) assay, neutral red (NR) uptake assay, and Coomassie brilliant blue (CBB) assay. Results revealed that these heavy metal salts were cytotoxic to the RF cell line at varied concentrations. MTD values were found to be 1.563, 3.125, 6.25, 12.5 and 25 mg/L for CdCl(2), CdSO(4), ZnCl(2), Zn(NO(3))(2) and ZnSO(4), respectively. The half-maximal inhibitory concentration values calculated by MTT, NR and CB assay were 53.83 ± 7.02, 58.03 ± 9.12 and 79.20 ± 15.27 for ZnSO(4), 26.44 ± 7.01, 36.60 ± 7.82 and 155.6 ± 14.75 for Zn(NO(3))(2), 20.26 ± 17.95, 16.94 ± 7.05 and 87.54 ± 7.58 for ZnCl(2), 5.166 ± 0.57, 15 ± 1 and 41.80 ± 8.38 for CdSO(4) and 4.966 ± 0.56, 9.56 ± 1.73 and 20.93 ± 4.47 for CdCl(2). This study establishes the RF cell line as an in vitro tool for assessment and monitoring of heavy metal concentration in the aquatic environment.

Enzymes as bionanoreactors: glucose oxidase for the synthesis of catalytic Au nanoparticles and Au nanoparticle-polyaniline nanocomposites.

The use of biomaterials such as enzymes for the synthesis of functional materials is important because such biologically guided processes can significantly reduce energy consumption in manufacturing processes. Glucose oxidase (GOx) has been exploited as a reducing as well as a stabilising agent for the green chemical synthesis of Au nanoparticles at pH 7.0 under ambient conditions. The synthesized Au nanoparticle-GOx composite was found to act as a highly-effective catalyst towards the reduction of p-nitrophenol to p-aminophenol in the presence of NaBH4. The catalytic activity of GOx was largely inhibited after its participation in the reduction of metal salt to form nanoparticles. A detailed mechanistic investigation was carried out using fluorescence spectroscopy, Fourier transform infra-red (FTIR) spectroscopy and circular dichroism (CD) to gain insights into the conformational changes in the enzyme structure. The catalytic activity of GOx towards the oxidation of glucose was taken advantage of to form a Au nanoparticle-polyaniline (Au NP-PANI) composite at room temperature. The production of the green emeraldine salt form of polyaniline (PANI) was extremely low in case of Au nanoparticle-GOx composite, where GOx was involved as a reducing agent. However, H2O2 generated during the catalytic reaction of GOx acted as a simultaneous reducing and oxidizing agent, leading to the formation of an Au NP-PANI core-shell composite in a controlled fashion.

Biogenic growth of alloys and core-shell nanostructures using urease as a nanoreactor at ambient conditions.

Biomineralization is an extremely efficient biologically guided process towards the advancement of nano-bio integrated materials. As a prime module of the natural world, enzymes are expected to play a major role in biogenic growth of inorganic nanostructures. Although there have been developments in designing enzyme-responsive nanoparticle systems or generation of inorganic nanostructures in an enzyme-stimulated environment, reports regarding action of enzymes as reducing agents themselves for the growth of inorganic nanoparticles still remains elusive. Here we present a mechanistic investigation towards the synthesis of metal and metallic alloy nanoparticles using a commonly investigated enzyme, Jack bean urease (JBU), as a reducing as well as stabilizing agent under physiological conditions. The catalytic functionality of urease was taken advantage of towards the development of metal-ZnO core-shell nanocomposites, making urease an ideal bionanoreactor for synthesizing higher order nanostructures such as alloys and core- shell under ambient conditions.

Carbon dot reduced palladium nanoparticles as active catalysts for carbon-carbon bond formation.

Carbon dots were used as a reducing agent for the synthesis of Pd nanoparticles coated with ultrathin carbon dot shells of ca. 4 nm. The resulting composite nanoparticles showed high catalytic activity for the Heck and Suzuki coupling reactions.