The continuous decrease in the availability of fossil resources, along with an evident energy crisis, and the growing environmental impact due to their use, has pushed scientific research towards the ...development of innovative strategies and green routes for the use of renewable resources, not only in the field of energy production but also for the production of novel advanced materials and platform molecules for the modern chemical industry. A new class of promising carbon nanomaterials, especially graphene quantum dots (GQDs), due to their exceptional chemical-physical features, have been studied in many applications, such as biosensors, solar cells, electrochemical devices, optical sensors, and rechargeable batteries. Therefore, this review focuses on recent results in GQDs synthesis by green, easy, and low-cost synthetic processes from eco-friendly raw materials and biomass-waste. Significant advances in recent years on promising recent applications in the field of electrochemical sensors, have also been discussed. Finally, challenges and future perspectives with possible research directions in the topic are briefly summarized.
The timely diagnosis of cancer represents the best chance to increase treatment success and to reduce cancer deaths. Nanomaterials-based biosensors containing graphene quantum dots (GQDs) as a ...sensing platform show great promise in the early and sensitive detection of cancer biomarkers, due to their unique chemical and physical properties, large surface area and ease of functionalization with different biomolecules able to recognize relevant cancer biomarkers. In this review, we report different advanced strategies for the synthesis and functionalization of GQDs with different agents able to selectively recognize and convert into a signal specific cancer biomarkers such as antigens, enzymes, hormones, proteins, cancer related byproducts, biomolecules exposed on the surface of cancer cells and changes in pH. The developed optical, electrochemical and chemiluminescent biosensors based on GQDs have been shown to ensure the effective diagnosis of several cancer diseases as well as the possibility to evaluate the effectiveness of anticancer therapy. The wide linear range of detection and low detection limits recorded for most of the reported biosensors highlight their great potential in clinics for the diagnosis and management of cancer.
A novel bidentate Schiff base (L) is here proposed for the detection of Zn ions in water. The structure of the synthesized Schiff base L was characterized by FT-IR,
H NMR and
C NMR. Optical ...characteristics were addressed by UV-Visible spectroscopy and Photoluminescence (PL) measurements. PL demonstrated that L displays a "turn-off" type fluorescence quenching in the presence of Zn
ion in aqueous solution, indicating its ability to preferentially coordinate this ion. Based on these findings, an L-M (where M is a suitable membrane) modified screen-printed carbon electrode (SPCE) was developed to evaluate the electrochemical behavior of the Schiff base (L) with the final objective of undertaking the electroanalytical determination of Zn ions in water. Using various electrochemical techniques, the modified L-M/SPCE sensor demonstrates high sensitivity and selectivity to Zn ions over some common interferents ions, such as Ca
, Mg
, K
, Ni
and Cd
. The potentiometric response of the L-M/SPCE sensor to Zn ions was found to be linear over a relatively wide concentration range from 1 μM to 100 mM.
Lignocellulosic biomasses have a tremendous potential to cover the future demand of bio-based chemicals and materials, breaking down our historical dependence on petroleum resources. The development ...of green chemical technologies, together with the appropriate eco-politics, can make a decisive contribution to a cheap and effective conversion of lignocellulosic feedstocks into sustainable and renewable chemical building blocks. In this regard, the use of an indirect H-source for reducing the oxygen content in lignocellulosic biomasses and in their derived platform molecules is receiving increasing attention. In this contribution we highlight recent advances in the transfer hydrogenolysis of cellulose, hemicellulose, lignin, and of their derived model molecules promoted by heterogeneous catalysts for the sustainable production of biofuels and biochemicals.
This review provides an overview of heterogeneous bimetallic Pd-Fe catalysts in the C–C and C–O cleavage of platform molecules such as C2–C6 polyols, furfural, phenol derivatives and aromatic ethers ...that are all easily obtainable from renewable cellulose, hemicellulose and lignin (the major components of lignocellulosic biomasses). The interaction between palladium and iron affords bimetallic Pd-Fe sites (ensemble or alloy) that were found to be very active in several sustainable reactions including hydrogenolysis, catalytic transfer hydrogenolysis (CTH) and aqueous phase reforming (APR) that will be highlighted. This contribution concentrates also on the different synthetic strategies (incipient wetness impregnation, deposition-precipitaion, co-precipitaion) adopted for the preparation of heterogeneous Pd-Fe systems as well as on the main characterization techniques used (XRD, TEM, H2-TPR, XPS and EXAFS) in order to elucidate the key factors that influence the unique catalytic performances observed.
Hybrid hydrogels composed of chitosan (CS) have shown great potential in bone tissue engineering and regeneration. The introduction of polyhedral oligomeric silsesquioxanes (POSS) in the biopolymeric ...matrix has been demonstrated to improve the rheological and biological properties of the hybrid composites. In this work, we have integrated the favourable features of chitosan (CS) and POSS nanoparticles to design new nanocomposites for bone tissue regeneration, focusing our attention on the effect of POSS concentration within the CS matrix (0.5, 1, and 1.5 equivalents in weight of POSS with respect to CS) on the chemical, physical, rheological, and in vitro biological properties of the final composites. The drug release ability of the synthesized hydrogel scaffolds were also investigated using, as the model drug, ketoprofen, that was included in the scaffold during the gelling procedure, showing a more controlled release for the hybrids with respect to CS (86-91% of drug released after two weeks). The results of the in vitro biological tests performed on human fetal osteoblastic cells (hFOB 1.19) culture demonstrated the great biocompatibility of the hybrid materials. The hybrids, at the different POSS concentrations, showed values of cell mortality superimposable with control cells (11.1 vs. 9.8%), thus revealing the CS/POSS hydrogels as possible candidates for bone tissue engineering applications.
Pure titanium and titanium alloys are widely used in dentistry and orthopedics. However, despite their outstanding mechanical and biological properties, implant failure mainly due to post-operative ...infection still remains a significant concern. The possibility to develop inherent antibacterial medical devices was here investigated by covalently inserting bioactive ammonium salts onto the surface of titanium metal substrates. Titanium discs have been functionalized with quaternary ammonium salts (QASs) and with oleic acid (OA), affording the Ti-AEMAC Ti-GTMAC, Ti-AUTEAB, and Ti-OA samples, which were characterized by ATR-FTIR and SEM-EDX analyses and investigated for the roughness and hydrophilic behavior. The chemical modifications were shown to deeply affect the surface properties of the metal substrates and, as a consequence, their bio-interaction. The bacterial adhesion tests against the Gram-negative
and Gram-positive
, at 1.5 and 24 h of bacterial contact, showed good anti-adhesion activity for Ti-AUTEAB and Ti-OA samples, containing a long alkyl chain between the silicon atom and the ammonium functionality. In particular, the Ti-AUTEAB sample showed inhibition of bacteria adhesion against
of about one log with respect to the other samples, after 1.5 h. The results of this study highlight the importance of chemical functionalization in addressing the antimicrobial activity of metal surfaces and could open new perspectives in the development of inherent antibacterial medical devices.
Ultra High molecular weight polyethylene (UHMWPE) suffers wear degradation in total joint replacements and it needs to be improved. Thus, we enhanced wear resistance of UHMWPE with carbon nanofiller ...and paraffin oil and studied its tribological behavior in Simulated Synovial Fluid (SSF) for 60 days at 37 °C to reproduce the conditions of a real joint. Ageing in biological fluid accelerates the wear action but nanocomposite exhibited a higher wear resistance compared to UHMWPE because of its higher structural homogeneity. Carbon nanofiller closes the porosity of UHMWPE hindering SSF to penetrate inside. Wear resistance of the nanocomposite with 1.0 wt.% of CNF improved of 65% (before ageing) and of 70% (after 60 days in SSF) with respect to pure UHMWPE.
The concentration of sodium and potassium ions in biological fluids, such as blood, urine and sweat, is indicative of several basic body function conditions. Therefore, the development of simple ...methods able to detect these alkaline ions is of outmost importance. In this study, we explored the electrochemical and optical properties of graphene quantum dots (GQDs) combined with the selective chelating ability of the crown ethers 15-crown-5 and 18-crown-6, with the final aim to propose novel composites for the effective detection of these ions. The results obtained comparing the performances of the single GQDs and crown ethers with those of the GQDs-15-crown-5 and GQDs-18-crown-6 composites, have demonstrated the superior properties of these latter. Electrochemical investigation showed that the GQDs based composites can be exploited for the potentiometric detection of Na
and K
ions, but selectivity still remains a concern. The nanocomposites showed the characteristic fluorescence emissions of GQDs and crown ethers. The GQDs-18-crown-6 composite exhibited ratiometric fluorescence emission behavior with the variation of K
concentration, demonstrating its promising properties for the development of a selective fluorescent method for potassium determination.
PDF
