Nitrogen and sulphur doped carbon dot: An excellent biocompatible candidate for in-vitro cancer cell imaging and beyond.

Carbon dots (CDs) are an exquisite class of carbon allotrope that is already well nourished for their good biocompatibility, water-solubility, excellent photostability, and magnificent photoluminescence property. Doping strategy with heteroatoms is an efficacious way to modify the physicochemical and optical properties, making the carbon dots an exceedingly potential candidate. This work reports the fabrication and cancer cell imaging application of photoluminescent heteroatom-doped carbon dots by use of cysteine and urea as carbon, nitrogen, and sulphur sources through a straightforward and highly productive hydrothermal procedure. The fabricated luminescent carbon dots are spherical in shape, with an average diameter of 3.5 nm. X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR) characterization revealed key facts about the surface functional groups and chemical compositions of carbon dots. The excitation-dependent photoluminescence (PL) peak appeared at around 445 nm against the excited wavelength of 350 nm. Moreover, under the provided experimental conditions, all the carbon dots are non-toxic and safe. The cytotoxicity and the safety profiles of the carbon dots were found to be in the bearable range under normal in-vitro experimental circumstances. Cellular uptake was observed by the green fluorescence of carbon dots inside cells. Likewise, the carbon dots did not alter the cell viability of the normal glial cell line. Again, when treated with the carbon dots, there was no notable increase of apoptotic cells in the G2/M phase of cell cycle analysis that confirmed the imaging-trackable ability of the carbon dots.

One-Dimensional NiSe-Se Hollow Nanotubular Architecture as a Binder-Free Cathode with Enhanced Redox Reactions for High-Performance Hybrid Supercapacitors.

Selenium-enriched nickel selenide (NiSe-Se) nanotubes supported on highly conductive nickel foam (NiSe-Se@Ni foam) were synthesized using chemical bath deposition with the aid of lithium chloride as a shape-directing agent. The uniformly grown NiSe-Se@Ni foam, with its large number of electroactive sites, facilitated rapid diffusion and charge transport. The NiSe-Se@Ni foam electrode exhibited a superior specific capacitance value of 2447.46 F g-1 at a current density value of 1 A g-1 in 1 M aqueous KOH electrolyte. Furthermore, a high-energy-density pouch-type hybrid supercapacitor (HSC) device was fabricated using the proposed NiSe-Se@Ni foam as the positive electrode, activated carbon on Ni foam as the negative electrode, and a filter paper separator soaked in 1 M KOH electrolyte solution. The HSC delivered a specific capacitance of 84.10 F g-1 at a current density of 4 mA cm-2 with an energy density of 29.90 W h kg-1 at a power density of 594.46 W kg-1 for an extended operating voltage window of 1.6 V. In addition, the HSC exhibited excellent cycling stability with a capacitance retention of 95.09% after 10,000 cycles, highlighting its excellent potential for use in the hands-on applications. The real-life practicality of the HSC was tested by using it to power a red light-emitting diode.

A Multifunctional Smart Textile Derived from Merino Wool/Nylon Polymer Nanocomposites as Next Generation Microwave Absorber and Soft Touch Sensor.

In recent times e-textiles have emerged as wonder safeguards due to the great potential background in space, military, healthcare, or portable electronics. As a result, widespread research and development have been done to make significant advancement in this field, but it still remains a key challenge to use one single product with multifunctional attributes with the past performance of key characteristics. In this work, phase-separated PEDOT:PSS ornamented with reduced graphene oxide (rGO) nanosheets, deposited on the newly fabricated ultralightweight, superhydrophobic, and mechanically enriched merino wool/nylon (W-N) composite textile followed by the dipping and drying strategy. The open edges-layered structure of rGO helping uniform deposition of PEDOTs clusters, which allows the formation of a stacked layer of PEDOTs/rGO-PEDOTs/PEDOTs for robust three-dimensional electrical transforming channel network within the W-N textile surface. These dip-coated multifunctional textiles show high electrical conductivities up to 90.5 S cm-1 conjugated with a flexible electromagnetic interference shielding efficiency of 73.8 dB (in X-band) and in-plane thermal conductivity of 0.81 W/mK with a minimum thickness of 0.84 mm. This thin coating maintained the hydrophobicity (water contact angle of ∼150°) leading to an excellent EM protective cloth combined with real-life antenna performance under high mechanical or chemical tolerance. Interestingly, this multiuse textile can also act as an exceptional TASER Proof Textile (TPT) due to a short out of the electrical shock coming from the TASER by its unique conducting network architecture. Remarkably, this coated textile can get a response by the soft touch to lighten up the household bulb and could establish wireless communication via an HC-05 Bluetooth module as a textile-based touch switch. This developed fabric could perform as a new potentially scalable single product in intelligent smart garments, portable next-generation electronics, and the growing threat of EM pollution.

Acoustic cavitation assisted destratified clay tactoid reinforced in situ elastomer-mimetic semi-IPN hydrogel for catalytic and bactericidal application.

Ultrasonicaion is non-chemical process where acoustic waves have been targeted to aqueous medium dispersed precursor materials. In situ synthesis of silver nanoparticles anchored in hydrogel matrix has been opted via ~20 kHz frequency assisted (bath sonication) synthesis having the ultrasonication power intensity (UPI) of ~106 J/m2. Power intensity is inversely proportional to the surface area of the clay tactoids. The hydrogel have been prepared by in situ 20 kHz assisted sonochemical destratification of laponite clay tactoids which could be terminologically stated as 'top-down method'. Silver nanoparticles (AgNPs) have been deposited in the surfaces of the porous matrix of hydrogel via 'soak and irradiate' method. Soaking of silver ions into the gel matrix is welcomed due to their efficient stabilization and fast transformation towards AgNPs. AgNPs played the key role in catalytic reduction and bactericidal activity. Moreover, the prepared hydrogel has enough robust to withstand cyclic stress, uniaxial stress and oscillatory stress which have been extensively justified by the physico-mechanical characterizations. The gel supported catalyst showed first order reaction kinetics and less time consuming period during reduction of 4-nitrophenol as a model pollutant.

Electrodeposited Cu2O Nanopetal Architecture as a Superhydrophobic and Antibacterial Surface.

Bacterial infections being sporadic and uncontrollable demands an urgent paradigm shift in the development of novel antibacterial agents. This work involves the fabrication of Cu2O nanopetals over copper foil that show superlative antibacterial and superhydrophobic properties. A superhydrophobic surface has been fabricated using the electrochemical deposition (ECD) method. Here, it is aimed to establish the superior antibacterial activity as an outcome of the inherent superhydrophobic property of the as-fabricated nanostructures. The present study finds that the elevated value of the water contact angle (154 ± 0.6°) does not allow proper bacterial adhesion, and it is immune from the possibility of biofouling. Specifically, two kinds of bacterial strains have been tested and the time response of the antibacterial activity has been studied over a period of 12 h, taking DH5α Escherichia coli as a Gram-negative model and Bacillus subtilis 168 as a Gram-positive model. Higher antibacterial effects were observed for the Gram-negative model (E. coli) owing to its simplistic cell wall structure which facilitates the easy diffusion of Cu+ ions into the bacterial membrane. The simplicity of the developed method of fabrication along with the superlative superhydrophobic nature and excellent antibacterial property of the material, owing to its synergistic biophysical and biochemical modes of biocidal action, establishes its viability in many applications.

Polysaccharide and poly(methacrylic acid) based biodegradable elastomeric biocompatible semi-IPN hydrogel for controlled drug delivery.

Nanoparticles embedded semi-interpenetrating (semi-IPNs) polymeric hydrogels with enhanced mechanical toughness and biocompatibility could have splendid biomedical acceptance. Here we propose poly(methacrylic acid) grafted polysaccharide based semi-IPNs filled with nanoclay via in situ Michael type reaction associated with covalent crosslinking with N,N-methylenebisacrylamide (MBA). The effect of nanoclay in the semi-IPN hydrogel has been investigated which showed significant improvement of mechanical robustness. Meanwhile, the hydrogels showed reversible ductility up to 70% in response to cyclic loading-unloading cycle which is an obvious phenomenon of rubber-like elasticity. The synthesized semi-IPN hydrogel show biodegradability and non-cytotoxic nature against human cells. The live-dead assay showed that the prepared hydrogel is a viable platform for cell growth without causing severe cell death. The in vitro drug release study in psychological pH (pH = 7.4) reveals that the controlled drug release phenomena can be tuned by simulating the environment pH. Such features in a single hydrogel assembly can propose this as high performance; biodegradable and non-cytotoxic 3D scaffold based promising biomaterial for tissue engineering.

Green Reduced Graphene Oxide Toughened Semi-IPN Monolith Hydrogel as Dual Responsive Drug Release System: Rheological, Physicomechanical, and Electrical Evaluations.

Macroporous hydrogel monoliths having tailor-made features, conductivity, superstretchability, excellent biocompatibility, and biodegradability, have become the most nurtured field of interest in soft biomaterials. Green method assisted reduced graphene oxide has been inserted by in situ free radical gelation into semi-IPN hydrogel matrix to fabricate conducting hydrogel. Mechanical toughness has been implemented for the graphene-polymer physisorption interactions with graphene basal planes. Moreover, the as-prepared 3D scaffold type monolith hydrogel has been rheologically superior regarding their high elastic modulus and delayed gel rupturing. κ-Carragenaan, one of the components of the hydrogel, has biodegradable nature. The most significant outcome is their low electrical percolation threshold and reversibly ductile nature. Reversible ductility provides them with rubber-like consistency in flow conditions. Surprising, the hydrogels showed dual stimuli-responsiveness, that is, environmental pH and external electrical stimulation. Electro-stimulation has been adopted here for the first time in semi-IPN systems, which could be an ideal alternative for iontopheretic devices and pulsatile drug release through skin. Regarding this, the hydrogel also has been passed to biocompatibility assay; they are noncytotoxic and show cell proliferation without negligible cell death in live-dead assay. The porosity of the nanocomposite scaffold-like gels was also analyzed by microcomputed tomography (µ-CT), which exhibited their connectivity in cell/voids inside the matrix. Thus, the experimentations are on the support of biocompatible soft material for dual-responsive tunable drug delivery.

Dual doped biocompatible multicolor luminescent carbon dots for bio labeling, UV-active marker and fluorescent polymer composite.

We report on metal-non-metal doped carbon dots with very high photoluminescent properties in solution. Magnesium doping to tamarind extract associated with nitrogen-doping is for the first time reported here which also produce very high quantum yield. Our aim is to develop such dual doped carbon dots which can also serve living cell imaging with easy permeation towards cells and show non-cytotoxic attributes. More importantly, the chemical signatures of the carbon dots unveiled in this work can support their easy solubilization into water; even in sub-ambient temperature. The cytotoxicity assay proves the almost negligible cytotoxic effect against human cell lines. Moreover, the use of carbon dots in UV-active marker and polymer composites are also performed which gave clear distinguishable features of fluorescent nanoparticles. Hitherto, the carbon dots can be commercially prepared without adopting any rigorous methods and also can be used as non-photo-bleachable biomarkers of living cells.

Mechanically robust dual responsive water dispersible-graphene based conductive elastomeric hydrogel for tunable pulsatile drug release.

Nanohybrid hydrogels based on pristine graphene with enhanced toughness and dual responsive drug delivery feature is opening a new era for smart materials. Here pristine graphene hydrogels are synthesized by in situ free radical polymerization where graphene platelets are the nanobuiliding blocks to withstand external stress and shows reversible ductility. Such uniqueness is a mere reflection of rubber-like elasticity on the hydrogels. These nanobuilding blocks serve also the extensive physisorption which enhances the physical crosslinking inside the gel matrix. Besides the pH-responsive drug release features, these hydrogels are also implemented as a pulsatile drug delivery device. The electric responsive drug release behaviours are noticed and hypothesized by the formation of conducting network in the polyelectrolytic hydrogel matrix. The hydrogels are also tested as good biocompatibility and feasible cell-attachment during live-dead cell adhesion study. The drug release characteristics can also be tuned by adjusting the conducting filler loading into the gel matrix. As of our knowledge, this type of hydrogels with rubber-like consistency, high mechanical property, tunable and dual responsive drug delivery feature and very good human cell compatible is the first to report.

Waste chimney oil to nanolights: A low cost chemosensor for tracer metal detection in practical field and its polymer composite for multidimensional activity.

Proper waste disposal from household and restaurants is becoming an important and recurring waste-management concern. Herein, a method of upcycling of waste kitchen chimney oil has been adopted to prepare fluorescent multifunctional carbon quantum dots. These nanodots showed superior biocompatibility, excellent optical properties, water solubility and high yield. Preparation of C-dots from highly abundant carbon source of waste refusals is highly effective in commercial aspect as well as in reducing the immense environmental pollution. The C-dots showed quasi-spherical size obtained from high resolution transmission electron microscopy (HRTEM) having an abundance of 1-4 nm in size. The ease of water dispersibility of the nanodots is a mere reflection of their surface polarity which has been supported by Fourier transformed infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). In the field of practical acceptability, the C-dots have been experimented to sense Fe3+ ion in a wide range of concentration (1 nM to 600 µM) with a detection limit of 0.18 nM which can be termed as 'tracer metal chemosensor'. Moreover, the prepared carbon dots were also tested against inter-cellular Fe3+ ion sensing probe. Lastly, we also fabricate the biopolymer­carbon dots composite for fluorescent marker ink and light emitting polymer film.

Design of psyllium-g-poly(acrylic acid-co-sodium acrylate)/cloisite 10A semi-IPN nanocomposite hydrogel and its mechanical, rheological and controlled drug release behaviour.

Soft biomaterials derived from polysaccharides are generally suffers from lack of mechanical robustness and instability. The naturally occurring highly abundance low cost polysaccharide has immense aspect as biomaterial after functionalization which can be designed as stretchable and rubber-like elastic with reversible ductility. A highly swellable, stretchable, low creep, non-cytotoxic nanocomposite hydrogel has been fabricated by simple one-pot Michael type covalent grafting of acrylic acid based copolymer onto psyllium biomacromolecular chian by free radical gelation technique. The fabricated hydrogel was rheologically tested which implies its viscoelastic and thixotropic like features. The porous morphology of the hydrogel was confirmed by scanning electron micrograph. The cryo-transmission electron micrograph shows the random dispersion of the nanoclay (cloisite 10A) tactoids in exfoliated as well intercalated forms. These random distributions of clay nanosheets also enhance the mechanical toughness and reversible ductility of the hydrogels which was also supported by the mechanical and loading-unloading cycle measurement. Nonetheless, the nanocomposite hydrogel was non-cytotoxic against human cell-line (human osteosarcoma) and shows good cell attachment of live cells in a 5-day 'live-dead' assay with almost negligible quantity of cell death. These attributes can promote this material as a soft biomaterial for controlled release device with mechanical robustness and rubber-like elasticity.

A strategy to achieve enhanced electromagnetic interference shielding at low concentration with a new generation of conductive carbon black in a chlorinated polyethylene elastomeric matrix.

The fabrication of scalable and affordable conductive Ketjen carbon black (K-CB)-elastomer composites for adjustable electromagnetic interference (EMI) shielding remains a difficult challenge. Herein, chlorinated polyethylene (CPE)-K-CB composites have been developed by single step solution mixing to achieve high EMI shielding performance associated with absorption dominance potency by conductive dissipation as well as the reflection of electromagnetic waves. The dispersion of K-CB inside the CPE matrix has been corroborated by electron micrographs and atomic force microscopy (AFM). The K-CB filler and CPE polymer interaction has been investigated through the bound rubber content (Bdr) and the dynamic mechanical properties. The relatively low loading of K-CB with respect to other conventional carbon fillers contributes to a promising low percolation threshold (9.6 wt% K-CB) and a reasonably high EMI shielding effectiveness (EMI SE) value of 38.4 dB (at 30 wt% loading) in the X-band region (8.2 to 12.4 GHz). Classical percolation theory reveals that the electrical conduction behavior through the composite system is quasi-two dimensional in nature. Our belief lies in the promotion of scalable production of flexible and cost-effective K-CB-CPE composites of superior EMI SE to avoid electromagnetic radiation pollution.

Shape and size of highly concentrated micelles in CTAB/NaSal solutions by Small Angle Neutron Scattering (SANS).

Highly concentrated micelles in CTAB/NaSal solutions with a fixed salt/surfactant ratio of 0.6 have been studied using Small Angle Neutron Scattering (SANS) as a function of temperature and concentration. A worm-like chain model analysis of the SANS data using a combination of a cylindrical form factors for the polydisperse micellar length, circular cross-sectional radius with Gaussian polydispersity, and the structure factor based on a random phase approximation (RPA) suggests that these micelle solutions have a worm-like micellar structure that is independent of the concentration and temperature. The size of the micelle decreases monotonically with increasing temperature and increases with concentration. These observations indicate that large micelles are formed at low temperature and begin to break up to form smaller micelles with increasing temperature.

Quantitative characterization of vertically aligned multi-walled carbon nanotube arrays using small angle X-ray scattering.

We have used small angle X-ray scattering (SAXS) to quantitatively characterize the morphology of vertically aligned (VA) multiwall carbon nanotube (MWCNT) arrays. We examined the extent of alignment of MWCNTs in terms of order parameter by analyzing SAXS intensity as a function of azimuthal angle. The SAXS measurements at different heights of CNT arrays from the substrate reveal two distinct morphologies and increasing alignment. We are able to quantitatively characterize a real variation in CNT diameters of the VA-MWCNTs through model fitting of the SAXS spectra. It found that the average CNT diameter increases with increasing distance from the substrate.