Salivary biomarkers of neurodegenerative and demyelinating diseases and biosensors for their detection

Salivary analysis is gaining increasing interest as a novel and promising field of research for the diagnosis of neurodegenerative and demyelinating diseases related to aging. The collection of saliva offers several advantages, being noninvasive, stress-free, and repeatable. Moreover, the detection of biomarkers directly in saliva could allow an early diagnosis of the disease, leading to timely treatments. The aim of this manuscript is to highlight the most relevant researchers’ findings relatively to salivary biomarkers of neurodegenerative and demyelinating diseases, and to describe innovative and advanced biosensing strategies for the detection of salivary biomarkers. This review is focused on five relevant aging-related neurodegenerative disorders (Alzheimer's disease, Parkinson's disease, Amyotrophic Lateral Sclerosis, Huntington's disease, Multiple Sclerosis) and the salivary biomarkers most commonly associated with them. Advanced biosensors enabling molecular diagnostics for the detection of salivary biomarkers are presented, in order to stimulate future research in this direction and pave the way for their clinical application

4D Printing of Plasmon-Encoded Tunable Polydimethylsiloxane Lenses for On-Field Microscopy of Microbes

Here the 4D printing of a magnifying polydimethylsiloxane (PDMS) lens encoded with a tunable plasmonic rejection filter is reported. The lens is formed by moldless printing of PDMS pre-polymer on a nanostructured porous silicon (PSi) templating layer. A nanometer-thick plasmonic filter is integrated on the lens surface by in situ synthesis of Ag and Au nanoparticles (NPs) with programmed density. The filter can be designed to reject light at the plasmonic resonance wavelength of the NPs with an optical density tunable from 0 to 3 and retreive light at longer wavelengths with a pass-to-stop band ratio tunable from 0 to 60 dB. Swelling of PDMS in hexane and ether is used to change the NP density on the lens surface and modulate, in turn, the transmittance properties of the NP-decorated lens over 3 orders of magnitude. The plasmon-encoded lens is coupled to a commercial smartphone demonstrating: shaping of the emission spectrum of a white light-emitting diode to tune the color from yellow to purple; real-time bright-field and fluorescence microscopy of living microbes in water, namely, the auto-fluorescent green alga Chlorogonium sp. and the ciliated protozoan Euplotes daidaleos

Programa Soja Livre Rondônia: safra 2011/2012.

Apresentação dos resultados do Programa Soja Livre Rondônia.bitstream/item/120818/1/CT-132-soja.pd

Maskless Preparation of Spatially-Resolved Plasmonic Nanoparticles on Polydimethylsiloxane via In Situ Fluoride-Assisted Synthesis

Here, a fluoride-assisted route for the controlled in-situ synthesis of metal nanoparticles (NPs) (i.e., AgNPs, AuNPs) on polydimethylsiloxane (PDMS) is reported. The size and coverage of the NPs on the PDMS surface are modulated with time and over space during the synthetic process, leveraging the improved yield (10×) and faster kinetics (100×) of NP formation in the presence of F− ions, compared to fluoride-free approaches. This enables the maskless preparation of both linear and step gradients and patterns of NPs in 1D and 2D on the PDMS surface. As an application in flexible plasmonics/photonics, continuous and step-wise spatial modulations of the plasmonic features of PDMS slabs with 1D and 2D AgNP gradients on the surface are demonstrated. An excellent spatially resolved tuning of key optical parameters, namely, optical density from zero to 5 and extinction ratio up to 100 dB, is achieved with AgNP gradients prepared in AgF solution for 12 minutes; the performance are comparable to those of commercial dielectric/interference filters. When used as a rejection filter in optical fluorescence microscopy, the AgNP-PDMS slabs are able to reject the excitation laser at 405 nm and retain the green fluorescence of microbeads (100 µm) used as test cases

Bioresorbable and Biodegradable Electronics and Photonics

Over the last decade, bioresorbable and biodegradable materials that fully dissolve with benign and biocompatible byproducts have been engineered into electrical, optical, and sensing transient components with applications, though not limited to, in personalized medicine and sportwellness activities. In this paper, state-of-the-art achievements on bioresorbable and biodegradable electronic and photonic devices and systems are reviewed and discussed

Decoration of Porous Silicon with Gold Nanoparticles via Layer-by-Layer Nanoassembly for Interferometric and Hybrid Photonic/Plasmonic (Bio)sensing

Gold nanoparticle layers (AuNPLs) enable the coupling of morphological, optical, and electrical properties of gold nanoparticles (AuNPs) with tailored and specific surface topography, making them exploitable in many bioapplications (e.g., biosensing, drug delivery, and photothermal therapy). Herein, we report the formation of AuNPLs on porous silicon (PSi) interferometers and distributed Bragg reflectors (DBRs) for (bio)sensing applications via layer-by-layer (LbL) nanoassembling of a positively charged polyelectrolyte, namely, poly(allylamine hydrochloride) (PAH), and negatively charged citrate-capped AuNPs. Decoration of PSi interferometers with AuNPLs enhances the Fabry-Pérot fringe contrast due to increased surface reflectivity, resulting in an augmented sensitivity for both bulk and surface refractive index sensing, namely, about 4.5-fold using NaCl aqueous solutions to infiltrate the pores and 2.6-fold for unspecific bovine serum albumin (BSA) adsorption on the pore surface, respectively. Sensitivity enhancing, about 2.5-fold, is also confirmed for affinity and selective biosensing of streptavidin using a biotinylated polymer, namely, negatively charged poly(methacrylic acid) (b-PMAA). Further, decoration of PSi DBR with AuNPLs envisages building up a hybrid photonic/plasmonic optical sensing platform. Both photonic (DBR stop-band) and plasmonic (localized surface plasmon resonance, LSPR) peaks of the hybrid structure are sensitive to changes of bulk (using glucose aqueous solutions) and surface (due to BSA unspecific adsorption) refractive index. To the best of our knowledge, this is the first report about the formation of AuNPLs via LbL nanoassembly on PSi for (i) the enhancing of the interferometric performance in (bio)sensing applications and (ii) the building up of hybrid photonic/plasmonic platforms for sensing and perspective biosensing applications

Alpha-naphthyl acetate esterase activity in mouse thymus and other lymphoid organs

Alpha-naphthyl acetate esterase (ANAE) reaction of mouse and rat thymus cells was studied. The majority of cells demonstrated ANAE in the form of multiple scattered granules. A reaction of this type appeared particularly labile, was found only when smears were fixed in formalin vapours and was inhibited by NaF. ANAE staining of thymus cells from mice of different ages was studied: the percentage of cells with single-spotted ANAE reaction was found to increase with age, while cells with granular scattered activity showed a progressive slight decrease. The percentage of ANAE positive cells in spleen appeared to be lower than in thymus, and showed only minor variations in different ages. In mouse and rat thymus and bowel lamina propria clusters of lymphocytes were found showing a sickle-shaped ANAE reaction, surrounding diffusely stained large cells which, on the basis of cytochemistry and phagocytosis ability, could be identified as macrophages. Analogous cell clusters were found in human tonsils and adenoids. These cell clusters were found to be similar to those formed by Ia-positive interdigitating cells which have been previously observed in human thymus, tonsils and bowel. The role of these clusters in the education process of lymphocytes is discusse

Solution-Processable Carbon Nanotube Nanohybrids for Multiplexed Photoresponsive Devices

Here, the formation of carbon nanotube (CNT)-based nanohybrids in aqueous solution is reported, where DNA-wrapped CNTs (DNA-CNTs) act as templates for the growth of PbS and CdS nanocrystals, toward the formation of PbS-DNA-CNT and CdS-DNA-CNT heterostructures. Solution-processed multiplexed photoresponsive devices are fabricated from these nanohybrids, displaying a sensitivity to a broad range of illumination wavelengths (405, 532, and 650 nm). The DNA-CNT and CdS-DNA-CNT devices show a drop in the current while PbS-DNA-CNT's current increases upon light illumination, indicating a difference in the operational mechanisms between the hybrids. Furthermore, the ON/OFF photoresponse of PbS-DNA-CNT is only 1 s as compared to 200 s for the other two nanohybrid devices. The mechanisms of the different photoresponses are investigated by comparing the performance under an inert and air atmosphere, and gate dependence device analysis and transient absorption spectroscopy measurements are also conducted. The results reveal that photoinduced oxygen desorption is responsible for the slower photoresponse by DNA-CNT and CdS-DNA-CNT, while photoinduced charge transfer dominates the much faster response of PbS-DNA-CNT devices. The strategy developed is of general applicability for the bottom-up assembly of CNT-based nanohybrid optoelectronic systems and the fabrication of solution-processable multiplexed devices