Gold-Coated Superparamagnetic Nanoparticles for Single Methyl Discrimination in DNA Aptamers

Biocompatible silane adhesion layer on titanium implants improves angiogenesis and osteogenesis

Silane adhesion layer strategy has been widely used to covalently graft biomolecules to the titanium implant surface, thereby conferring the implant bioactivity to ameliorate osseointegration. However, few researchers pay attention to the effects of silanization parameters on biocompatibility and biofunctionality of the silane adhesion layers. Accordingly, the present study successfully fabricated the silane adhesion layers with different thickness, intactness, and surface morphologies by introducing 3-aminopropyltriethoxysilane on the alkali-treated titanium surface in time-varied processing of silanization. The regulatory effects of the silane adhesion layers on angiogenesis and osteogenesis were assessed in vitro. Results showed that the prolonged silanization processing time increased the thickness and intactness of the silane adhesion layer and significantly improved its biocompatibility. Notably, the silane adhesion layer prepared after 12 h of silanization exhibited a brain-like surface morphology and benefited the adhesion and proliferation of endothelial cells (ECs) and osteoblasts (OBs). Moreover, the layer promoted angiogenesis via stimulating vascular endothelial growth factor (VEGF) secretion and nitric oxide (NO) production of ECs. Simultaneously, it improved osteogenesis by enhancing alkaline phosphatase (ALP) activity, collagen secretion, and extracellular matrix mineralization of OBs. This work systematically investigated the biocompatibility and biofunctionality of the modified silane adhesion layers, thus providing valuable references for their application in covalently grafting biomolecules on the titanium implant surface.

Recent Advances in Electrochemical Biosensors: Applications, Challenges, and Future Scope

The electrochemical biosensors are a class of biosensors which convert biological information such as analyte concentration that is a biological recognition element (biochemical receptor) into current or voltage. Electrochemical biosensors depict propitious diagnostic technology which can detect biomarkers in body fluids such as sweat, blood, feces, or urine. Combinations of suitable immobilization techniques with effective transducers give rise to an efficient biosensor. They have been employed in the food industry, medical sciences, defense, studying plant biology, etc. While sensing complex structures and entities, a large data is obtained, and it becomes difficult to manually interpret all the data. Machine learning helps in interpreting large sensing data. In the case of biosensors, the presence of impurity affects the performance of the sensor and machine learning helps in removing signals obtained from the contaminants to obtain a high sensitivity. In this review, we discuss different types of biosensors along with their applications and the benefits of machine learning. This is followed by a discussion on the challenges, missing gaps in the knowledge, and solutions in the field of electrochemical biosensors. This review aims to serve as a valuable resource for scientists and engineers entering the interdisciplinary field of electrochemical biosensors. Furthermore, this review provides insight into the type of electrochemical biosensors, their applications, the importance of machine learning (ML) in biosensing, and challenges and future outlook.

Synthesis and Characterization of Citrate-Stabilized Gold-Coated Superparamagnetic Iron Oxide Nanoparticles for Biomedical Applications

Surface-functionalized gold-coated superparamagnetic iron oxide nanoparticles (Au-SPIONs) may be a useful tool in various biomedical applications. To obtain Au-SPIONs, gold salt was precipitated onto citrate-stabilized SPIONs (Cit-SPIONs) using a simple, aqueous one-pot technique inspired by the Turkevich method of gold nanoparticle synthesis. By the further stabilization of the Au-SPION surface with additional citrate (Cit-Au-SPIONs), controllable and reproducible Z-averages enhanced long-term dispersion stability and moderate dispersion pH values were achieved. The citrate concentration of the reaction solution and the gold/iron ratio was found to have a major influence on the particle characteristics. While the gold-coating reduced the saturation magnetization to 40.7% in comparison to pure Cit-SPIONs, the superparamagnetic behavior of Cit-Au-SPIONs was maintained. The formation of nanosized gold on the SPION surface was confirmed by X-ray diffraction measurements. Cit-Au-SPION concentrations of up to 100 µg Fe/mL for 48 h had no cytotoxic effect on Jurkat cells. At a particle concentration of 100 µg Fe/mL, Jurkat cells were found to take up Cit-Au-SPIONs after 24 h of incubation. A significantly higher attachment of thiol-containing L-cysteine to the particle surface was observed for Cit-Au-SPIONs (53%) in comparison to pure Cit-SPIONs (7%).

Synthesis, transfer, and characterization of core-shell gold-coated magnetic nanoparticles

Magnetic separation has gained new popularity as a versatile partitioning method with the recent growth in nanotechnology and related biotechnology applications. In this study, iron oxide magnetic nanoparticles were synthesized via solvothermal methods and directly coated with gold to form core-shell gold-coated magnetic nanoparticles (Fe₃O₄-AuNPs). High-resolution transmission electron microscopy with Energy dispersive X-ray spectroscopy results suggests that temperature and reaction time play an important role in the formation of small, monodisperse Fe₃O₄-AuNPs. We also demonstrate that increased 4- dimethyl(amino)pyridine (DMAP) concentrations and vigorous stirring were required to successfully transfer Fe₃O₄-AuNPs into aqueous solution. The structure and morphology of the synthesized and transferred Fe₃O₄-AuNPs was further confirmed by UV–vis absorption spectroscopy and solubility experiments.

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Direct coating of Fe₃O₄ with Au: Slowly heating by (10 °C/ min) until 180–190 °C without exceeding this reaction temperature and increasing the reaction time to 3 h from 1.5 h

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High yield transfer of Fe₃O₄-AuNPs was achieved using 4- dimethyl(amino)pyridine (DMAP) as phase transfer catalyst

Novel Alkali Activation of Titanium Substrates To Grow Thick and Covalently Bound PMMA Layers

Titanium (Ti) is the most widely used metal in biomedical applications because of its biocompatibility; however, the significant difference in the mechanical properties between Ti and the surrounding tissues results in stress shielding which is detrimental for load-bearing tissues. In the current study, to attenuate the stress shielding effect, a new processing route was developed. It aimed at growing thick poly(methyl methacrylate) (PMMA) layers grafted on Ti substrates to incorporate a polymer component on Ti implants. However, the currently available methods do not allow the development of thick polymeric layers, reducing significantly their potential uses. The proposed route consists of an alkali activation of Ti substrates followed by a surface-initiated atom transfer radical polymerization using a phosphonic acid derivative as a coupling agent and a polymerization initiator and malononitrile as a polymerization activator. The average thickness of the grown PMMA layers is approximately 1.9 μm. The Ti activation-performed in a NaOH solution-leads to a porous sodium titanate interlayer with a hierarchical structure and an open microporosity. It promotes the covalent grafting reaction because of high hydroxyl groups' content and enables establishing a further mechanical interlocking between the growing PMMA layer and the Ti substrate. As a result, the produced graduated structure possesses high Ti/PMMA adhesion strength (∼260 MPa). Moreover, the PMMA layer is (i) thicker compared to those obtained with the previously reported techniques (∼1.9 μm), (ii) stable in a simulated body fluid solution, and (iii) biocompatible. This strategy opens new opportunities toward hybrid prosthesis with adjustable mechanical properties with respect to host bone properties for personalized medicines.

Chemical Sensors and Biosensors in Italy: A Review of the 2015 Literature

The contributions of Italian researchers to sensor research in 2015 is reviewed. The analysis of the activities in one year allows one to obtain a snapshot of the Italian scenario capturing the main directions of the research activities. Furthermore, the distance of more than one year makes meaningful the bibliometric analysis of the reviewed papers. The review shows a research community distributed among different scientific disciplines, from chemistry, physics, engineering, and material science, with a strong interest in collaborative works.

Synthesis of Water Dispersible and Catalytically Active Gold-Decorated Cobalt Ferrite Nanoparticles

Hetero-nanoparticles represent an important family of composite nanomaterials that in the past years are attracting ever-growing interest. Here, we report a new strategy for the synthesis of water dispersible cobalt ferrite nanoparticles (CoxFe3-xO4 NPs) decorated with ultrasmall (2-3 nm) gold nanoparticles (Au NPs). The synthetic procedure is based on the use of 2,3-meso-dimercaptosuccinic acid (DMSA), which plays a double role. First, it transfers cobalt ferrite NPs from the organic phase to aqueous media. Second, the DMSA reductive power promotes the in situ nucleation of gold NPs in proximity of the magnetic NP surface. Following this procedure, we achieved a water dispersible nanosystem (CoxFe3-xO4-DMSA-Au NPs) which combines the cobalt ferrite magnetic properties with the catalytic features of ultrasmall Au NPs. We showed that CoxFe3-xO4-DMSA-Au NPs act as an efficient nanocatalyst to reduce 4-nitrophenol to 4-aminophenol and that they can be magnetically recovered and recycled. It is noteworthy that such nanosystem is more catalytically active than Au NPs with equal size. Finally, a complete structural and chemical characterization of the hetero-NPs is provided.