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Multi-stimuli responsive lanthanide based tough luminescent hydrogels were engineered using hydrophobic and metal–ligand interactions.

Bacterial invasion is a serious concern during the wound healing process. The colonization of bacteria is mainly responsible for the pH fluctuation at the wound site. Therefore, the fabrication of a proper wound dressing material with antibacterial activity and pH monitoring ability is necessary to acquire a fast healing process. Therefore, this work is dedicated to designing a vitamin B12-loaded gelatin microsphere (MS) decorated with a carbon dot (CD) metal-organic framework (MOF) for simultaneous pH sensing and advanced wound closure application. The resultant MS portrayed a high specific surface area and a hierarchically porous structure. Furthermore, the surface of the resultant MS contained numerous carboxyl groups and amine groups whose deprotonation and protonation with the pH alternation are accountable for the pH-sensitive properties. The vitamin B12 release study was speedy from the MOF structure in an acidic medium, which was checked by gelatin coating, and a controlled drug release behavior was observed. The system showed excellent cytocompatibility toward the L929 cell line and remarkable antibacterial performance against Gram-negative

Carbon nanotubes (CNTs) impart great multi-functionality when reinforced with a polymer matrix. This paper shows the qualitative and quantitative improvements of the mechanical, electrical, and electromagnetic interference shielding effectiveness properties with the additions of the multiwalled carbon nanotubes (MWCNTs) and functionalized MWCNTs (FMWCNTs) in ethylene methyl acrylate (EMA) polymer. Mechanical characterization is performed through tensile testing, and electromagnetic interference shielding effectiveness (EMI SE) is calculated from the scattering parameters obtained from the vector network analyzer. Both properties improve compared to neat polymer with the reinforcement loadings up to a critical value, from where the properties start to degrade due to the agglomeration of the CNTs. FMWCNTs provide better performance in terms of properties over the MWCNT reinforced nanocomposites. Morphological characterization using a scanning electron microscope justifies a lower percolation threshold of FMWCNT/EMA composite by better electrical conductive network formation. At 10 wt% of FMWCNT loading, the FMWCNT/EMA composite shows 25.1 dB of EMI shielding efficiency combined with excellent mechanical and electrical properties extending its potential use in both industry and academia as an excellent flexible EMI shielding material.

The present work investigates the time-dependent antibacterial activity of the silver nanodot decorated dendritic copper foam nanostructures against Escherichia coli (Gram-negative) and Bacillus subtilis (Gram-positive) bacteria. An advanced antibacterial and antifouling surface is fabricated utilizing the collective antibacterial properties of silver nanodots, chitosan, and dendritic copper foam nanostructures. The porous network of the Ag nanodot decorated Cu foam is made up of nanodendrites, which reduce the wettability of the surface. Hence, the surface exhibits hydrophobic nature and inhibits the growth of bacterial flora along with the elimination of dead bacterial cells. The fabricated surface exhibits a water contact angle (WCA) of 158.7 ± 0.17°. Specifically, we tested the fabricated material against both the Gram-positive and Gram-negative bacterial models. The antibacterial activity of the fabricated surface is evident from the growth inhibition percentage of bacterial strains of Escherichia coli (72.30 ± 0.60%) and Bacillus subtilis (48.30 ± 1.71%). The micrographs obtained from scanning electron microscopy (SEM), transmission electron microscopy (TEM), and atomic force microscopy (AFM) of the treated cells show the damaged cellular structures of the bacteria, which is strong evidence of successful antibacterial action. The antibacterial effect can be attributed to the synergistic mechano-chemo mode of action involving mechanical disruption of the bacterial cell wall by the nanoprotrusions present on the Cu dendrites along with the chemical interaction of the Ag nanodots with vital intracellular components.

The present study emulates a one-pot facile synthesis of selenium-enriched CoSe nanotube using a chemical bath deposition (CBD) procedure. Schematic incorporation of 3D Ni foam current collectors as substrates for the growth of CoSe–Se nanotubes helped us achieve a binder-less thin film coating. The controlled synthesis of CoSe–Se nanotube was carried out by optimizing the temperature and time of the deposition. CoSe–Se nanotubes were grown on a porous Ni foam substrate using lithium chloride as a shape directing agent. The study found that the one dimensional structure of the nanotubes with porous nature results in an uninterrupted network of electroactive sites. Due to the superior conductivity, the as-fabricated material exhibited excellent rate capability and a higher degree of electrolyte ion diffusion across the CoSe–Se crystal structure. The CoSe–Se@Ni foam electrodes exhibited a specific capacitance of 1750.81 F g−1 at 1 A g−1. The electrode exhibited excellent cycling stability and showed a capacitance retention of 95% after 4000 charge-discharge cycles. Finally, an asymmetric supercapacitor (ASC) device was fabricated with the as-synthesized CoSe–Se@Ni foam electrode as the cathode, activated carbon@Ni foam electrode as the anode, and a thin filter paper separator soaked in 1 M aqueous KOH electrolyte solution. The ASC device showed a specific capacitance value of 106.73 F g−1 at 0.5 A g−1, and achieved an energy density of 37.94 Wh kg−1 at a power density of 475.30 W kg−1. The ASC device was utilized in an extended potential window of 1.6 V. The fabricated device displayed exceptional cycling stability with a capacitance retention of 93% after 5000 charge-discharge cycles.

In recent years, there has been a great interest in preparing polymers from bioresources, as this practice has several advantages over petrobased polymers. Thermoplastic elastomers (TPEs) are an interesting class of polymers that can be easily processed, reused, and recycled. The terpene, β-Myrcene (MY), is an important vinylic monomer having a conjugated diene in the backbone, which has a resemblance to the isoprene unit, a building block for natural rubber. MY is available from several bioresources like hops, lemongrass, bay plants, and so forth. In this work, reversible addition–fragmentation chain-transfer (RAFT) polymerization was used for the very first time to prepare an ABA-type triblock copolymer, polystyrene-b-poly(β-myrcene)-b-polystyrene (SMS), where poly(β-myrcene) acted as the soft block and polystyrene (PS) as the hard block. For this, styrene was initially polymerized using S,S-dibenzyl trithiocarbonate as a bifunctional RAFT agent, and the resultant PS was then used as a macro-RAFT agent to polymerize MY to attain SMS triblock copolymers. The successful preparation of the block copolymers (BCPs) was confirmed by NMR, FTIR, and GPC analyses. The DSC and AFM analyses showed the phase-separated morphology of hard and soft domains of PS and PMY, respectively. These SMS BCPs showed good tensile properties and a low tension set of 4.12%, indicating their application as a potential TPE. The scrapes of these SMS BCPs were successfully recycled and reused, indicating the sustainability of the process for this potential TPE.

Respiratory infections by RNA viruses are one of the major burdens on global health and economy. Viruses like influenza or coronaviruses can be transmitted through respiratory droplets or contamina...

Polymer waste is an “Achilles heel” in the product life cycle and can cause environmental pollution. Different methods can be used to reprocess such waste, including incineration and recycling, whi...

Ethylene propylene diene (EPDM)–chlorobutyl rubber (CIIR) blends can withstand both radiation and hydrocarbon environments and are used for elastomeric components in nuclear plants. This work inves...

Conventional fillers such as carbon black (CB) have been widely used in the tire industry as a reinforcing material. Despite the low cost, this filler poses the problem of agglomeration and the requirement of high filler loading in the polymer matrices. An alternative to the conventional filler, the two-dimensional nanomaterials are gaining increased research interests. Graphene, one of the strongest in-plane tensile strength material that belongs to the family of carbon, are widely being used for preparing the polymer nanocomposites. Besides having a wide variety of applications, this material serves as a reinforcing medium in polymer matrices. Resin matrices are characterized as high viscous material and have poor physicomechanical properties. The preparation of the resin/graphene composite can increase the mechanical properties and form a stable structure under dynamic loading. Modification of the graphene filler increases the interfacial adhesion and increases the uniform dispersion in the resin or polymeric matrix. Uniformly dispersed filler matrix have higher mechanical properties compared to the pristine graphene and conventional CB filler. The addition of this two-dimensional filler in the elastomer also reinforce the matrix and have low energy loss under dynamic loading.

For the last few decades, revolutionary scientific research regarding carbon related nanomaterials (carbon nanotubes, graphene, etc.) and the corresponding polymer-based nanocomposites in nanoscience is helping to modernize the functionality and applicability of various electronic devices of different catagories. Graphene-based polymer nanocomposites are having their applications in the field of gas sensors, field effect transistors (FET), super capacitors, electromagnetic interference shielding materials (EMI), etc. The modification of graphene nanoparticle is also a neccessary parameter to apply for a specific electronic application as well. The present chapter discusses the synthesis of graphene nanomaterial, modification of the graphene nanomaterials, and graphene-polymer nanocomposites. The present chapter deals with the synthesis and modification of graphene, modified graphene, and its polymer nanocomposites in the electronics field mainly FET, supercapacitor, sensors, EMI shielding, etc.

Currently, polymer nanocomposites are occupying a major domain in high performance lightweight materials. Fiber reinforced polymer composites always remain in the first row among all the composite materials because of their high Young’s modulus and strength to weight ratio with respect to conventionally used metallic components for aerospace material. However, over the last few years, the motivation has been concentrated in the direction of nanocomposites material to improve longevity, and fuel efficiency of the aircrafts. This chapter focuses on the current status of research on the properties and applications of graphene-based polymer composite structures used in aerospace engineering. The polymers and fillers used in aerospace applications; the reason for graphene and its derivatives suitability in aerospace engineering were also illustrated.

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 ...

Membrane distillation (MD) is an emerging separation technology that operates at the expense of less thermal energy. During this process, warmer feed water flows on one side of the microporous membrane, and cooler distillate collects at the permeate side or in a condenser. The temperature difference on both sides of the membrane creates the vapor pressure difference that facilitates the diffusion of vapors through the pores. Vapors condense at the permeate side, leaving highly concentrated solute at the feed stream; a theoretical 100% rejection of pollutants is one of the most significant advantages of this separation technique. Also, the requirement of lower temperature, utilization of the waste heat energy left during the various industrial processes, and reduced membrane fouling makes this process highly demanding over the traditional reverse osmosis. The primary requirement of the MD is the membrane hydrophobicity, which keeps a nonwetting membrane surface and ameliorates the diffusion of vapors through the pores. Recently, polymeric and two-dimensional nanomaterial (graphene and graphene analogs) membranes are widely used for the MD application. Hence, progress in developing the materials for this separation technology is also an interest of this chapter.

Electrically conducting flexible polymeric nanocomposite has been fabricated through wet mixing method where conducting inclusion was acoustically exfoliated pristine graphene nanosheets. Colloidal graphene is the key component here which has been prepared by acoustic cavitation in the presence of macromolecular dispersion. The significance of the method is their green preparation strategy without using any chemical reducing agents and long self-life without drastic sedimentation rate. Thermoplastic poly(ethylene-co-methyl acrylate) was chosen as flexible phase where graphene sheets were distributed to make spatial conducting network architecture. The prepared nanocomposites showed 0.259 S/cm DC electrical conductivity and frequency-independent electroconducting character in higher concentration. The electromagnetic interference shielding effectiveness of the nanocomposites was around 30 dB in ~ 1.0 mm thickness in X-band (8.2–12.4 GHz) frequency range without affecting its mechanical toughness and flexibility. Thus, such pristine graphene-based thermoplastic matrix could be a desirable replacement of metallic shielding materials on the ground of flexible, conducting, lightweight characteristics.

Background: Human Papilloma Virus (HPV) infection is associated with the development of several cancers, including oral, esophageal, skin, lung, and uterine cervix. Association of HPV and colorectal cancers remains controversial. The aim of this study was to evaluate the association between HPV infection and colorectal cancer in Chattogram of Bangladesh. Materials and methods: The study was carried out in the Department of Pathology, Chattogram Medical College, Bangladesh over a period of one year from July, 2013 to June, 2014. A total of 60 cases were included in the study during the time period. Histopathological type and grading was done. HPV type 16 and 18 DNA was examined from all samples by means of Real Time PCR using type specific primer named E7 protein. Finally association between HPV types 16/18 with colorectal carcinoma was assessed by Chi-square (c2) test. Results: The mean age of 60 patients was 45.35 years (Range 17-75 years). Rectum was the common site of tumour 26 (43.3%). HPV type 16 and 18 was detected in 25 (41.7%) cases, out of whom 24 (96%) were associated with HPV16, and only one case was both HPV type 16 and 18. As regarding histological type, out of 25 cases 21 (84%) cases of adenocarcinoma, 3 (12%) case of signet ring carcinoma and only 1 (1.6%) case of mucinous carcinoma were positive for HPV. Conclusion: HPV specially subtype 16, may play a role in the oncogenesis of Colorectal Carcinoma. Chatt Maa Shi Hosp Med Coll J; Vol.18 (1); Jan 2019; Page 44-48

Detection of sugar by enzymatic assay has been suffering from costly, time-taking, instable and denaturation of glucose oxidase. Recently, chemosensors that have affinity towards boronate became the hot topic in the domain of monosaccharide detection. In this work, a novel strategy was addressed to fabricate carbon dots (C-dots) from linear sulfated polysaccharides κ- carrageenan and phenyl boronic acid for nonenzymatic monosaccharide (glucose) detection. The boronic acid group anchored C-dots surface can form assembly by covalently bonded with the cis-diol moiety of the glucose which caused fluorescence quenching of the C-dots. The inert surface nature of the luminescent C-dots enables them to sense as low as 1.7 μM glucose without the interference of other biomolecules. The proposed sensing system was successfully applied for assay of glucose in blood serum. Interestingly, these C-dots were used as a nano vehicle for delivery of anti-diabetic drug Metformin. Good biocompatibility results were found with MTT and hemolysis assay. Owing to its simplicity and effectiveness, the as-prepared C-dots offered great promise for blood sugar diagnosis and treatment.

Graphene oxide (or graphene) derived graphene quantum dots (GQDs) are the primary building blocks for nano-devices because of their superior electronic, thermal, optical and toughening (in matrix) characteristics. There are various methods to prepare GQDs where “top-down” method has been practiced widely. This is a size reduction technique from micrometer sized graphene sheets to nanometer sized (

In this study, facile hydrothermal synthesis of carbon dots was developed from seaweed-derived κ-carrageenan and lemon juice followed by surface quaternization with benzalkonium chloride for the first time to improve fluorescence properties. The as-prepared spherical carbon dots (KLBC-dots) exhibited excellent water solubility, significant upconversion photoluminescence and excellent photostability. We report small angle neutron scattering (SANS) experiments with the C-dots which illustrate their surface fractals and the proneness of the C-dots to coalescence before and after surface passivation. Selective monitoring of aquatic chromium is critically significant owing to its severe toxic and carcinogenic properties, which have a dramatic impact on health and the environment. It is a remarkable fact that these KLBC-dots can serve as an “on–off–on” fluorescent platform for the selective sensing of Cr(VI) based on the inner filter effect (IFE). Ascorbic acid was employed to validate the “off–on” type fluorescent probe. Using this phenomenon, a logic gate based on the novel KLBC-dots has been constructed. This bifunctional nanosensor affords a very low detection limit (7 nM) and has the obvious benefits of rapid response, simplicity, convenience, high sensitivity and selectivity in practical applications. In addition, these carbon dots showed intracellular Cr(VI) detection and interesting antibacterial activity towards the Gram-negative bacteria E. coli. This study delivers multifunctional applications of KLBC-dots, as an antibacterial agent and for Cr(VI) detection, in environmental fields.

Delivery of therapeutics to the intestinal region bypassing the harsh acidic environment of the stomach has long been a research focus. On the other hand, monitoring a system's pH during drug delivery is a crucial diagnosis factor as the activity and release rate of many therapeutics depend on it. This study answered both of these issues by fabricating a novel nanocomposite hydrogel for intestinal drug delivery and near-neutral pH sensing at the same time. Gelatin nanocomposites (GNCs) with varying concentrations of carbon dots (CDs) were fabricated through simple solvent casting methods. Here, CDs served a dual role and simultaneously acted as a cross-linker and chromophore, which reduced the usage of toxic cross-linkers. The proposed GNC hydrogel sample acted as an excellent pH sensor in the near-neutral pH range and could be useful for quantitative pH measurement. A model antibacterial drug (cefadroxil) was used for the in vitro drug release study at gastric pH (1.2) and intestinal pH (7.4) conditions. A moderate and sustained drug release profile was noticed at pH 7.4 in comparison to the acidic medium over a 24 h study. The drug release profile revealed that the pH of the release medium and the percentage of CDs cross-linking influenced the drug release rate. Release data were compared with different empirical equations for the evaluation of drug release kinetics and found good agreement with the Higuchi model. The antibacterial activity of cefadroxil was assessed by the broth microdilution method and found to be retained and not hindered by the drug entrapment procedure. The cell viability assay showed that all of the hydrogel samples, including the drug-loaded GNC hydrogel, offered acceptable cytocompatibility and nontoxicity. All of these observations illustrated that GNC hydrogel could act as an ideal pH-monitoring and oral drug delivery system in near-neutral pH at the same time.

New elastomer-modified brake friction composites with the identical composition, but differing in the type of rubber, were developed by altering polar/non-polar elastomeric phases into the phenolic resin matrix. Effect of dispersion and interaction of the polar/non-polar rubbers with the matrix resin on dry sliding wear characteristics of the friction composites was investigated using a laboratory-scale pin-on-disc tribometer. The composites were prepared by hot mixing followed by compression molding and post-curing at a high temperature. Coefficient of friction (COF) and specific wear rate of the composites sliding against a cast-iron disc were measured and analyzed. Polar acrylonitrile-butadiene rubber (NBR, both powder, and bale rubber), and non-polar styrene-butadiene rubber (SBR) and ethylene-propylene-diene monomer (EPDM) were used with the phenolic resin where rubber islands and its polarity played the key role in delayed stress dissipation, while the hard matrix phase contributed to the intrinsic strength of the composites. This work describes how the distribution and interaction of polar and non-polar rubbers with the matrix resin influence the performance of brake friction composites. NBR (powder)-phenolic composite showed the highest stable average COF of 0.52 as compared to 0.36 for EPDM-based composite. NBR (powder)-based composite also exhibited ~1.5 times better specific wear rate (4.9 × 10−3 mm3 N−1 m−1) than EPDM-based composite (7.2 × 10−3 mm3 N−1 m−1). However, EPDM rubber-based composite showed a significant enhancement in thermal conductivity (0.43 W/m K). Morphological analyses revealed that the dispersion of rubber phase in phenolic matrix played a significant role in transforming the wear mechanism from abrasive to adhesive.

Respiratory infections by RNA viruses are one of the major burdens upon global health and economy. Viruses like influenza or coronaviruses can be transmitted through respiratory droplets or contaminated surfaces. An effective antiviral coating can decrease the viability of the virus particles in the outside environment significantly, hence reducing their transmission rate. In this work, we have screened a series of nanoparticles and their composites for antiviral activity using Nano Luciferase based highly sensitive influenza A reporter virus. Using this screening system, we have identified copper-graphene (Cu-Gr) nanocomposite shows strong antiviral activity. Extensive material and biological characterization of the nanocomposite suggested a unique metal oxide embedded graphene sheet architecture that can inactivate the virion particles only within 30 minutes of pre-incubation and subsequently interferes with the entry of these virion particles into the host cell. This ultimately results in reduced viral gene expression, replication and production of progeny virus particles, slowing down the overall pace of progression of infection. Using PVA as a capping agent, we have been able to generate a Cu-Gr nanocomposite based highly transparent coating that retains its original antiviral activity in the solid form.

Thermoplastic and thermosetting polymers are widely exploited for various industrial and commercial applications. Thermoplastics have gained significant attention in the civic society owing to their recyclability and reusability. In general, commodity plastics are thermoplastic materials. Engineering polymers that are used for automotive, electrical, and space applications include both thermoplastic and thermosetting polymers. Impregnation of various nanoparticles in a polymer matrix makes what is called a polymer nanocomposite, and this method can be used to attain optimum properties. These properties can be extended for use in various applications such as in a hydrogel or in membrane, or in biomedical, antimicrobial, or electromagnetic interference contexts.

Fluorescent nanoprobe has been judiciously tailored after incorporation of nitrogen and sulphur in carbon dots. The synergistic occurrence of sulphur and nitrogen affords outstanding luminescence property and provides recognition sites for specific and selective sensing of acetone (ketone) with an ultra-low limit of detection (7.2 × 10−7 M). This nano probe was successfully endorsed with real biological samples such as human blood and urine. The prepared carbon dots possess very high quantum yield (69.27%), excellent water dispersibility, non-toxic and ultrahigh photostability. Herein, we demonstrate an innovative perspective on the commercialization of carbon dots as a potential substitute to expensive kit for the detection of ketone bodies in human fluids.

The objective was to investigate the rheological and thermo-chemical behavior of asphalt-rubber (AR) binders and to evaluate the effect of various parameters on AR binder performance. The effort encompassed binder consistency, rheological, thermogravimetric, and Fourier transform infrared spectroscopy analyses of twelve different asphalts. It was found that CR inclusions not only improved the physical characteristics but also influenced the chemical and thermal properties of asphalt binder. Furthermore, it was inferred that employing higher CR dosages and fine CR gradations in asphalt binder will aid in producing an outstanding AR binder capable of performing well under extreme traffic and environmental conditions.

Herein, phase inversion poly(vinylidene fluoride)/poly(methyl methacrylate) (PVDF/PMMA) microporous membranes were prepared at various PMMA concentration by immersion precipitation method. Increment in the PMMA concentration has a significant influence in the PVDF membrane crystallinity, which is studied by differential scanning calorimeter, X-ray diffractometer, and small-angle X-ray scattering analyses. Properties such as membrane bulk structure, porosity, hydrophilicity, mechanical stability, and water flux vary in terms of PMMA concentration. Porosity is increased, and tensile strength decreased when PMMA concentration is beyond 30 wt %. Thermodynamic instability during the liquid to solid phase separation and variation in the crystallinity has an intense effect on these membrane properties. Then, 70/30 blend membrane selected as optimum composition owing to the high porosity and pure water flux compared to other compositions. This membrane is modified with a composite filler derived from the graphene oxide and titanate crosslinked by chitosan. The antibacterial, antifouling, and bovine serum albumin separation studies reveal that the developed nanocomposite membrane is a potential candidate for the separation application.

Epoxidized natural rubber (ENR) is a modified form of NR bearing polar epoxy groups. The focus is on dispersion of highly dispersible silica (HDS) filler with three different specific surface areas in ENR 25/ENR 50 composites. The effect of three different specific surface areas of HDS on bound rubber content, Payne effect, physicomechanical properties, and viscoelastic properties of the green composites was studied in detail. Also, the influences of epoxide content in ENRs in the absence of silane coupling agent are evaluated on the overall properties of green composites. The highest level of reinforcement was obtained for the intermediate specific surface area of HDS due to the homogenous dispersion in the ENR matrix. Small-angle X-ray scattering (SAXS) has been used to analyze the particle network and cluster establishment in the green composites. The present SAXS method provides a unique insight into the aggregate formation according to the Beaucage model. On the other hand, SAXS results demonstrate that the particle network can be efficiently suppressed by increasing the specific surface area of HDS.