Microcantilevers and organic transistors: two promising classes of label-free biosensing devices which can be integrated in electronic circuits.

Most of the success of electronic devices fabricated to actively interact with a biological environment relies on the proper choice of materials and efficient engineering of surfaces and interfaces. Organic materials have proved to be among the best candidates for this aim owing to many properties, such as the synthesis tunability, processing, softness and self-assembling ability, which allow them to form surfaces that are compatible with biological tissues. This review reports some research results obtained in the development of devices which exploit organic materials' properties in order to detect biologically significant molecules as well as to trigger/capture signals from the biological environment. Among the many investigated sensing devices, organic field-effect transistors (OFETs), organic electrochemical transistors (OECTs) and microcantilevers (MCLs) have been chosen. The main factors motivating this choice are their label-free detection approach, which is particularly important when addressing complex biological processes, as well as the possibility to integrate them in an electronic circuit. Particular attention is paid to the design and realization of biocompatible surfaces which can be employed in the recognition of pertinent molecules as well as to the research of new materials, both natural and inspired by nature, as a first approach to environmentally friendly electronics.

Characterization and evaluation of chitosan nanoparticles for dopamine brain delivery.

The aim of this study was to characterize nanoparticles (NPs) composed of chitosan (CS) and evaluate their potential for brain delivery of the neurotransmitter Dopamine (DA). For this purpose, CS based NPs were incubated with DA at two different concentrations giving rise to nanocarriers denoted as DA/CSNPs (1) and DA/CSNPs (5), respectively. X-ray Photoelectron Spectroscopy (XPS) analysis confirmed that DA was adsorbed onto the external surface of such NPs. The cytotoxic effect of the CSNPs and DA/CSNPs was assessed using the MTT test and it was found that the nanovectors are less cytotoxic than the neurotransmitter DA after 3 h of incubation time. Transport studies across MDCKII-MDR1 cell line showed that DA/CSNPs (5) give rise to a significant transport enhancing effect compared with the control and greater than the corresponding DA/CSNPs (1). Measurement of reactive oxygen species (ROS) suggested a low DA/CSNPs neurotoxicity after 3 h. In vivo brain microdialysis experiments in rat showed that intraperitoneal acute administration of DA/CSNPs (5) (6-12 mg/kg) induced a dose-dependent increase in striatal DA output. Thus, these CS nanoparticles represent an interesting technological platform for DA brain delivery and, hence, may be useful for Parkinson's disease treatment.

Dopamine-loaded chitosan nanoparticles: formulation and analytical characterization.

The formulation and characterization of dopamine (DA)-loaded chitosan nanoparticles (CSNPs) are described as preliminary steps for the development of potential DA carrier systems intended for Parkinson's disease treatment. For this purpose, CSNPs were firstly produced and, afterwards, they were incubated in a DA aqueous solution to promote neurotransmitter loading. The characterization of the resulting nanoparticles started with Fourier transform infrared spectroscopy analysis to ascertain the presence of DA in the nanocarrier, whereas X-ray photoelectron spectroscopy analysis provided evidence of the localization of DA on the nanoparticle surface. A quartz crystal microbalance with dissipation monitoring (QCM-D) was then exploited to investigate both swelling of CSNPs and interaction of DA with CSNPs. In particular, the QCM-D revealed that this interaction is fast and so this allows a stable nanostructured system to be obtained.

Development and characterization of rhVEGF-loaded poly(HEMA-MOEP) coatings electrosynthesized on titanium to enhance bone mineralization and angiogenesis.

Osteointegration of titanium implants could be significantly improved by coatings capable of promoting both mineralization and angiogenesis. In the present study, a copolymeric hydrogel coating, poly-2-hydroxyethyl methacrylate-2-methacryloyloxyethyl phosphate (P(HEMA-MOEP)), devised to enhance calcification in body fluids and to entrap and release growth factors, was electrosynthesized for the first time on titanium substrates and compared to poly-2-hydroxyethyl methacrylate (PHEMA), used as a blank reference. Polymers exhibiting negatively charged groups, such as P(HEMA-MOEP), help to enhance implant calcification. The electrosynthesized coatings were characterized by X-ray photoelectron spectroscopy and atomic force microscopy. MG-63 human osteoblast-like cell behaviour on the coated specimens was investigated by scanning electron microscopy, MTT viability test and osteocalcin mRNA detection. The ability of negatively charged phosphate groups to promote hydroxyapatite-like calcium phosphate deposition on the implants was explored by immersing them in simulated body fluid. Similar biological responses were observed in both coated specimens, while calcium-phosphorus globules were detected only on P(HEMA-MOEP) surfaces pretreated with alkaline solution. Testing of the ability of P(HEMA-MOEP) hydrogels to entrap and release human recombinant vascular endothelial growth factor, to tackle the problem of insufficient oxygen and nutrient delivery, suggested that P(HEMA-MOEP)-coated titanium prostheses could represent a multifunctional material suitable for bone restoration applications.