Strategies in the fabrication of modified graphene nanomaterials: prospects in the electrochemical sensing of biomolecules and anticancer effects

Being one of the highly explored nanomaterials, graphene and derivatives are in the limelight of scientific research. The quest of mass production of graphene in a fast, eco-friendly and economical way lead to different greener synthesis approaches with reduced risk and harm to the environment. Here through this investigation, different greener approaches in the preparation of graphene and its derivatives were analysed. Moreover, the biocompatibility of the product is analysed for ensuring the safety while introducing as a biomaterial to a living system. The initial part of the study, a hydrothermal reduction method was utilized to reduce graphene oxide (GO) to create reduced graphene oxide (RGO) without using any toxic reducing agents. Following this, with the use of a variety of ultrasonic cavitation, a profoundly stable (>2 year) few layer thick RGO nanodispersion was generated without employing any stabilizers. The excellent stability at physiological pH promotes its utilization of RGO dispersion as a carrier of Paclitaxel (Ptx) – an anticancer drug. The in vitro cytotoxicity analysis of the Ptx loaded RGO nanodispersion revealed the potential of the nanodispersion as a suitable drug carrier. RGO dispersion is also utilized in combination with glucose oxidase (GOD) enzyme, for the detection of glucose. RGO-GOD modified working glassy carbon (GC) electrode was evaluated to analyze the redox reaction in the presence of oxygen. This investigation demonstrated the potential of the exceptionally stable RGO nanodispersion in nano drug delivery and electrochemical sensing applications. Development of RGO nanodispersion through ultrasonication lead to the idea of creating graphene (G) sheets from graphite through ultrasonic exfoliation. Upon success of the G production, the next part of the research focused on the sonochemical development of graphene-gold (G-Au) nanocomposite through simultaneous exfoliation of graphite as well as the reduction of gold chloride. The G-Au nanocomposite was well characterized and utilized to fabricate an electrochemical sensor for the selective detection of nitric oxide (NO), a critical biomarker associated with numerous physiological and pathological abnormalities. The cytotoxic effects of the sonochemically synthesized G, AuNPs and G-Au nanocomposite were conducted on mammalian cell lines revealed the selective cytotoxic effects towards cancer cells and biocompatible nature towards normal cells. Biocompatibility results supported the use of the G-Au nanocomposite system for anticancer applications such as drug delivery, imaging, etc. Next part of the research used a natural reducing agent for reducing GO to RGO, utilizing a medicinal mushroom- Ganoderma lucidum (G.l.) extract. Similarly reduced graphene oxide-silver (RGO-Ag) nanocomp osite also was prepared by the facile one-step synthesis method. The properties of RGO-Ag obtained were well characterized and tested for sensing of hydrogen peroxide (H2O2), a cancer biomarker. Similarly, the antimicrobial potential of RGO-Ag was tested on different bacterial species. Furthermore, the cytotoxicity of RGO-Ag was tested on mammalian cell lines exhibited good biocompatibility. The sensing studies revealed the potential of RGO-Ag in H2O2detection. The antibacterial studies of RGO-Ag displayed comparable results with standard antibiotic Chloramphenicol. The antibacterial effects, sensing potential and selective toxicity towards cancer and normal cells make this RGO-Ag nanocomposite a promising candidate for future health care industry. Last part of the study focused on an electrochemical biosensor for the detection of cancer. Nanomaterials in combination with biomolecules are used in drug delivery, imaging and sensing applications by targeting the overexpressed cancer proteins such as folate receptors (FR), to control the disease from progressing to advanced levels. Here, a biocompatible RGO nanosheets (produced using G.l. extract) in combination with folic acid (FA), a vitamin with high bio-affinity to FR, is utilized for the development of an electrochemical sensor for the detection of cancer. The formation of RGO-FA nanocomposite was confirmed by various characterization techniques. The RGO-FA modified GC electrode was analysed by differential pulse voltammetry (DPV) for its accurate detection towards FR. This RGO-FA modified electrode showed good specificity and reliability when tested against similar interfering biomolecules. This RGO-FA sensor offers a great promise to the future medical industry through its highly sensitive detection of FR in a fast, reliable and in an economical way

Interactions between wear and corrosion on cast and sintered Ti-12Nb alloy in comparison with the commercial Ti-6Al-4V alloy

This work investigates the corrosion and tribocorrosion behavior of alpha + beta Ti-12Nb alloy processed by casting and sintering, in 9 g/l NaCl solution at body temperature, and compares the results with the commercial Ti-6Al-4 V alloy. Different electrochemical techniques were used to access the corrosion behavior. Tribocorrosion behavior was studied at open circuit potential under continuous and intermittent sliding, and at anodic potentiostatic condition under continuous sliding. Results revealed that Ti-12Nb alloys presented similar tribocorrosion behavior although the sintered one exhibited a better corrosion behavior. Nevertheless, Ti-6Al-4 V presented better overall degradation resistance than both Ti-12Nb alloys.- This work was supported by FCT national funds, under the national support to R&D units grant, through the reference project UIDB/04436/2020 and UIDP/04436/2020, together with M-ERA-NET/0001/2015, and co-supported by Brazilian agencies CNPq [grants #308.204/2017-4 and #125.954/2018-2] and FAPESP M-ERA-NET [grant #2015/50.280-5], also by MINECO (Spain) through the program PCIN-2016-123 and the Ramon y Cajal project RYC-2014-15014. I. Caha is grateful for a PhD grant under the NORTE-08-5369-FSE-000012 project

Introductory programming: a systematic literature review

As computing becomes a mainstream discipline embedded in the school curriculum and acts as an enabler for an increasing range of academic disciplines in higher education, the literature on introductory programming is growing. Although there have been several reviews that focus on specific aspects of introductory programming, there has been no broad overview of the literature exploring recent trends across the breadth of introductory programming. This paper is the report of an ITiCSE working group that conducted a systematic review in order to gain an overview of the introductory programming literature. Partitioning the literature into papers addressing the student, teaching, the curriculum, and assessment, we explore trends, highlight advances in knowledge over the past 15 years, and indicate possible directions for future research

Synthesis of graphene oxide and graphene quantum dots from miscanthus via ultrasound-assisted mechano-chemical cracking method

Whilst graphene materials have become increasingly popular in recent years, the followed synthesis strategies face sustainability, environmental and quality challenges. This study proposes an effective, sustainable and scalable ultrasound-assisted mechano-chemical cracking method to produce graphene oxide (GO). A typical energy crop, miscanthus, was used as a carbon precursor and pyrolysed at 1200 ◦C before subjecting to edgecarboxylation via ball-milling in a CO2-induced environment. The resultant functionalised biochar was ultrasonically exfoliated in N-Methyl-2-pyrrolidone (NMP) and water to form GOs. The intermediate and endproducts were characterised via X-ray diffraction (XRD), Raman, high-resolution transmission electron microscopy (HR-TEM) and atomic force microscopy (AFM) analyses. Results show that the proposed synthesis route can produce good quality and uniform GOs (8–10% monolayer), with up to 96% of GOs having three layers or lesser when NMP is used. Ultrasonication proved to be effective in propagating the self-repulsion of negativelycharged functional groups. Moreover, small amounts of graphene quantum dots were observed, illustrating the potential of producing various graphene materials via a single-step method. Whilst this study has only investigated utilising miscanthus, the current findings are promising and could expand the potential of producing good quality graphene materials from renewable sources via green synthesis routes

Atrasentan and renal events in patients with type 2 diabetes and chronic kidney disease (SONAR): a double-blind, randomised, placebo-controlled trial

Background: Short-term treatment for people with type 2 diabetes using a low dose of the selective endothelin A receptor antagonist atrasentan reduces albuminuria without causing significant sodium retention. We report the long-term effects of treatment with atrasentan on major renal outcomes. Methods: We did this double-blind, randomised, placebo-controlled trial at 689 sites in 41 countries. We enrolled adults aged 18–85 years with type 2 diabetes, estimated glomerular filtration rate (eGFR)25–75 mL/min per 1·73 m 2 of body surface area, and a urine albumin-to-creatinine ratio (UACR)of 300–5000 mg/g who had received maximum labelled or tolerated renin–angiotensin system inhibition for at least 4 weeks. Participants were given atrasentan 0·75 mg orally daily during an enrichment period before random group assignment. Those with a UACR decrease of at least 30% with no substantial fluid retention during the enrichment period (responders)were included in the double-blind treatment period. Responders were randomly assigned to receive either atrasentan 0·75 mg orally daily or placebo. All patients and investigators were masked to treatment assignment. The primary endpoint was a composite of doubling of serum creatinine (sustained for ≥30 days)or end-stage kidney disease (eGFR <15 mL/min per 1·73 m 2 sustained for ≥90 days, chronic dialysis for ≥90 days, kidney transplantation, or death from kidney failure)in the intention-to-treat population of all responders. Safety was assessed in all patients who received at least one dose of their assigned study treatment. The study is registered with ClinicalTrials.gov, number NCT01858532. Findings: Between May 17, 2013, and July 13, 2017, 11 087 patients were screened; 5117 entered the enrichment period, and 4711 completed the enrichment period. Of these, 2648 patients were responders and were randomly assigned to the atrasentan group (n=1325)or placebo group (n=1323). Median follow-up was 2·2 years (IQR 1·4–2·9). 79 (6·0%)of 1325 patients in the atrasentan group and 105 (7·9%)of 1323 in the placebo group had a primary composite renal endpoint event (hazard ratio [HR]0·65 [95% CI 0·49–0·88]; p=0·0047). Fluid retention and anaemia adverse events, which have been previously attributed to endothelin receptor antagonists, were more frequent in the atrasentan group than in the placebo group. Hospital admission for heart failure occurred in 47 (3·5%)of 1325 patients in the atrasentan group and 34 (2·6%)of 1323 patients in the placebo group (HR 1·33 [95% CI 0·85–2·07]; p=0·208). 58 (4·4%)patients in the atrasentan group and 52 (3·9%)in the placebo group died (HR 1·09 [95% CI 0·75–1·59]; p=0·65). Interpretation: Atrasentan reduced the risk of renal events in patients with diabetes and chronic kidney disease who were selected to optimise efficacy and safety. These data support a potential role for selective endothelin receptor antagonists in protecting renal function in patients with type 2 diabetes at high risk of developing end-stage kidney disease. Funding: AbbVie