PEO-PPO-PEO surfactant exfoliated graphene cyclodextrin drug carriers for photoresponsive release

Liquid exfoliated graphene sheets were incorporated within α-cyclodextrin-triblock copolymer supramolecular hydrogels prepared with a range of polyethylene oxide and polypropylene oxide block sizes and ratios allowing control over the release properties. The strong photothermal activity of graphene was employed to externally activate drug release from within the gels using near-infrared (NIR) irradiation. These supramolecular hybrid hydrogels showed thermoreversible changes in viscosity, which is necessary for an injectable, multiple release point drug delivery depot. This hybrid graphene-surfactant-α-CD gel system with thermoreversible properties is demonstrated herein to be externally NIR activated to induce controllable drug release.S.M.N. acknowledge financial support under the ARC Future Fellowship scheme FT100100177

An efficient naphthalimide based receptor for selective detection of Hg2+and Pb2+ions

Naphthalimide based receptor 1 with N-substituted benzothiazole and pyrrolidine subunit is designed, synthesized, and characterized using FT-IR,1H and 13C NMR spectroscopy and mass spectrometry techniques. The receptor 1 exhibits prominent optical response for Hg2+and Pb2+ions allowing the detection of these ions in acetonitrile (ACN). The formation of the receptor 1:cation complexes have been investigated using UV-Vis and fluorescence emission titration. Further, the selectivity of the receptor 1towards Hg2+and Pb2+ ions on the presence of various interfering cations such as Mg2+, Ba2+, Ni2+, Co2+, Cu2+, Ag2+, Fe2+, Fe3+and Cr3+ has been confirmed by UV-Vis and fluorescence spectroscopy. The binding constant between receptor 1 and Hg2+ and Pb2+ was estimated by Benesi-Hildebrand plot and equations. The binding constants have been found to be Ka= 3.43286 ´ 10−6 and Ka= 2.84079 ´ 10−6 M for Hg2+ and Pb2+, respectively. The limit of detection (LOD) for Hg2+and Pb2+by receptor 1are down to 7.44 ´ 10−10 M and 1.26 ´ 10−9 M, respectively. In addition, Job’s plot analysis reveals 1:2 binding stoichiometry between the receptor 1 and Pb2+ and Hg2+ cations.

Properties, synthesis, and applications of carbon dots: A review

Carbon dots (CDs) refer to a class of carbon-based nanoparticles with various subgroups based on their crystallinity and morphology. CDs offer tuneable physical, chemical, and optical properties, which can be controlled using simple one-pot synthesis techniques. In addition, their non-toxicity, biocompatibility, chemical and physical responsiveness, resistance to photo- and chemical-bleaching and low cost pave the way to a wide range of applications. The synthesis of CDs can be achieved via two approaches: (i) the top-down methods, and (ii) bottom-up methods. These two approaches can be designed to generate the intended chemical structures with specific band gap, hetero-atom doping, and chemical functionality. Further ongoing research enables us to understand the relationship between structural and optical properties of CDs. The photoluminescence of CDs depends on various parameters including synthesis methods, starting materials, surface states, and heteroatom doping etc. Herein, we review the various synthesis approaches and the properties of CDs such as the optical, physical, chemical, and structural properties resulting from the particles synthesis design. Also, proposed applications of CDs such as biomedicine, light emitting diodes, anticounterfeiting, and sensing are presented, where the main challenges in sensing applications and strategies to overcome these challenges are introduced

Current perspectives for engineering antimicrobial nanostructured materials

Pathogenic microorganisms are becoming a global health issue. Bacterial adhesion and growth on an implant surface form biofilms, endangering the fate of biomaterial in the body. Local infection from the infected implant increases patient mortality. Antibiotic-resistant bacteria have necessitated the development of new antibiotic generations. Nanotechnology is a growing field of science that has the potential to create new antibacterial materials. This concise review focuses on several new emerging antimicrobial areas: nanostructured surfaces/nanoparticles, polymer conformations, and two-dimensional antibacterial nanomaterials. Traditional antimicrobial drugs can be triggered by smart stimuli like the environments (pH, moisture, etc.) or physical stimulation like magnetic field and light. A special focus is devoted to the most recent advances in liquid metal particles that can be activated by external stimuli. Conformations of antibacterial polymers have also caught researcher interest owing to their unique bactericidal processes. The review concludes with the authors’ vision for the future directions of the field

Psychology of sport and exercise

In this study, we describe a biodegradable vaccine depot which persists invivo for at least 4-months, provides synergistic adjuvant effects and also allows dose sparing of both antigen and adjuvant. A single administration results in immediate release of a priming dose of vaccine, by a process of syneresis, which is then followed by release of remaining vaccine which maintains robust antibody levels that last for more than a year. The platform technology comprises two aqueous components; one contains chitosan and hydroxyapatite, in which the vaccine is incorporated, and the other consists of a crosslinking agent, tripolyphosphate (TPP) and chondroitin sulphate. When co-injected into tissue, they spontaneously crosslink forming a firm yet compliant vaccine-containing depot. Whole body imaging of animals inoculated with the material show that the depot persists in situ for up to 19 weeks. Vaccination of mice with depot formulations containing ovalbumin (OVA) emulsified in Montanide ISA 61 adjuvant results in the induction of robust antibody responses using doses of adjuvant 40-fold less than those recommended by the manufacturer. Dose sparing effects were also apparent with antigen when delivered in the depot. Similar dose sparing effects were observed with Montanide ISA 50, complete and incomplete Freund's adjuvants but not with aluminium hydroxide nor Quil A. Antibody titres, induced by a single dose of antigen/adjuvant formulation incorporated in the depot, persisted at high levels for at least 55 weeks following a single dose of vaccine

Pyrene-Phosphonate Conjugate: Aggregation-Induced Enhanced Emission, and Selective Fe3+ Ions Sensing Properties

A new pyrene-phosphonate colorimetric receptor 1 has been designed and synthesized in a one-step process via amide bond formation between pyrene butyric acid chloride and phosphonate-appended aniline. The pyrene-phosphonate receptor 1 showed aggregation-induced enhanced emission (AIEE) properties in water/acetonitrile (ACN) solutions. Dynamic light scattering (DLS) characterization revealed that the aggregates of receptor 1 at 80% water fraction have an average size of ≈142 nm. Field emission scanning electron microscopy (FE-SEM) analysis confirmed the formation of spherical aggregates upon solvent evaporation. The sensing properties of receptor 1 were investigated by UV-vis, fluorescence emission spectroscopy, and other optical methods. Among the tested metal ions, receptor 1 is capable of recognizing the Fe3+ ion selectively. The changes in spectral measurements were explained on the basis of complex formation. The composition of receptor 1 and Fe3+ ions was determined by using Job’s plot and found to be 1:1. The receptor 1–Fe3+ complex showed a reversible UV-vis response in the presence of EDTA

Investigation of Hg sorption and diffusion behavior on ultra-thin films of gold using QCM response analysis and SIMS depth profiling

Using the quartz crystal microbalance (QCM) technique, we demonstrate that the contribution of Hg adsorption and absorption on the sensor response profile can be distinguished by studying the dynamic response curve of QCM based Hg vapor sensors that employ an ultra-thin film of Au in the range of 10 to 40 nm thickness as the sensitive layer. The response magnitudes of the QCMs were extrapolated to zero thickness (ETZT) in an attempt to determine the contribution of adsorbed Hg on the sensor response magnitude and response profile. In general, the ratio of adsorbed to absorbed Hg on Au films is found to decrease with increased Hg vapor concentration. Furthermore, the same ratio was observed to decrease with increasing Au film thickness. The 10 nm and 40 nm Au films for example were found to contain adsorbed Hg content of 43.8% and 16.4%, respectively, with the balance attributed to absorption/amalgamation, when exposed to Hg vapor concentration of 10.55 mg m(-3) for a period of 14 hours and an operating temperature of 28 degrees C. In addition, the QCMs were characterized using secondary ion mass spectroscopy depth profiling in order to study the diffusion behaviour of Hg in the Au surfaces. It is deduced that in order to reduce Hg accumulation in Au thin films, a non-continuous type film (similar to the 10 nm ultra-thin Au sensitive layer morphology) would be more functional as a Hg sensitive layer where quick absorption and desorption processes are required

The Fate of Osteoblast-Like MG-63 Cells on Pre-Infected Bactericidal Nanostructured Titanium Surfaces

Biomaterials that have been newly implanted inside the body are the substratum targets for a “race for the surface„, in which bacterial cells compete against eukaryotic cells for the opportunity to colonize the surface. A victory by the former often results in biomaterial-associated infections, which can be a serious threat to patient health and can undermine the function and performance of the implant. Moreover, bacteria can often have a ‘head start’ if implant contamination has taken place either prior to or during the surgery. Current prevention and treatment strategies often rely on systemic antibiotic therapies, which are becoming increasingly ineffective due to a growing prevalence of antibiotic-resistant bacteria. Nanostructured surfaces that kill bacteria by physically rupturing bacterial cells upon contact have recently emerged as a promising solution for the mitigation of bacterial colonization of implants. Furthermore, these nanoscale features have been shown to enhance the adhesion and proliferation of eukaryotic cells, which is a key to, for example, the successful osseointegration of load-bearing titanium implants. The bactericidal activity and biocompatibility of such nanostructured surfaces are often, however, examined separately, and it is not clear to what extent bacterial cell-surface interactions would affect the subsequent outcomes of host-cell attachment and osseointegration processes. In this study, we investigated the ability of bactericidal nanostructured titanium surfaces to support the attachment and growth of osteoblast-like MG-63 human osteosarcoma cells, despite them having been pre-infected with pathogenic bacteria. MG-63 is a commonly used osteoblastic model to study bone cell viability, adhesion, and proliferation on the surfaces of load-bearing biomaterials, such as titanium. The nanostructured titanium surfaces used here were observed to kill the pathogenic bacteria, whilst simultaneously enhancing the growth of MG-63 cells in vitro when compared to that occurring on sterile, flat titanium surfaces. These results provide further evidence in support of nanostructured bactericidal surfaces being used as a strategy to help eukaryotic cells win the “race for the surface„ against bacterial cells on implant materials

The effect of coatings and nerve growth factor on attachment and differentiation of pheochromocytoma cells

Cellular attachment plays a vital role in the differentiation of pheochromocytoma (PC12) cells. PC12 cells are noradrenergic clonal cells isolated from the adrenal medulla of Rattus norvegicus and studied extensively as they have the ability to differentiate into sympathetic neuron-like cells. The effect of several experimental parameters including (i) the concentration of nerve growth factor (NGF); (ii) substratum coatings, such as poly-L-lysine (PLL), fibronectin (Fn), and laminin (Lam); and (iii) double coatings composed of PLL/Lam and PLL/Fn on the differentiation process of PC12 cells were studied. Cell morphology was visualised using brightfield phase contrast microscopy, cellular metabolism and proliferation were quantified using a 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assay, and the neurite outgrowth and axonal generation of the PC12 cells were evaluated using wide field fluorescence microscopy. It was found that double coatings of PLL/Lam and PLL/Fn supported robust adhesion and a two-fold enhanced neurite outgrowth of PC12 cells when treated with 100 ng/mL of NGF while exhibiting stable metabolic activity, leading to the accelerated generation of axons

Unusual Nature of Fingerprints and the Implications for Easy-to-Clean Coatings

Irrespective of the technology, we now rely on touch to interact with devices such as smart phones, tablet computers, and control panels. As a result, touch screen technologies are frequently in contact with body grease. Hence, surface deposition arises from localized inhomogeneous finger-derived contaminants adhering to a surface, impairing the visual/optical experience of the user. In this study, we examined the contamination itself in order to understand its static and dynamic behavior with respect to deposition and cleaning. A process for standardized deposition of fingerprints was developed. Artificial sebum was used in this process to enable reproducibility for quantitative analysis. Fingerprint contamination was shown to be hygroscopic and to possess temperature- and shear-dependent properties. These results have implications for the design of easily cleanable surfaces