In
an ideal plasmonic surface sensor, the bioactive area, where analytes
are recognized by specific biomolecules, is surrounded by an area
that is generally composed of a different material. The latter, often
the surface of the supporting chip, is generally hard to be selectively
functionalized, with respect to the active area. As a result, cross
talks between the active area and the surrounding one may occur. In
designing a plasmonic sensor, various issues must be addressed: the
specificity of analyte recognition, the orientation of the immobilized
biomolecule that acts as the analyte receptor, and the selectivity
of surface coverage. The objective of this tutorial review is to introduce
the main rational tools required for a correct and complete approach
to chemically functionalize plasmonic surface biosensors. After a
short introduction, the review discusses, in detail, the most common
strategies for achieving effective surface functionalization. The
most important issues, such as the orientation of active molecules
and spatial and chemical selectivity, are considered. A list of well-defined
protocols is suggested for the most common practical situations. Importantly,
for the reported protocols, we also present direct comparisons in
term of costs, labor demand, and risk vs benefit balance. In addition,
a survey of the most used characterization techniques necessary to
validate the chemical protocols is reported.
In this review we present the state of the art and the most recent advances in the field of optical sensing with hybrid plasmonic–photonic whispering gallery mode (WGM) resonators.
Retinal dystrophies such as Retinitis pigmentosa are among the most prevalent causes of inherited legal blindness, for which treatments are in demand. Retinal prostheses have been developed to stimulate the inner retinal network that, initially spared by degeneration, deteriorates in the late stages of the disease. We recently reported that conjugated polymer nanoparticles persistently rescue visual activities after a single subretinal injection in the Royal College of Surgeons rat model of Retinitis pigmentosa. Here we demonstrate that conjugated polymer nanoparticles can reinstate physiological signals at the cortical level and visually driven activities when microinjected in 10-months-old Royal College of Surgeons rats bearing fully light-insensitive retinas. The extent of visual restoration positively correlates with the nanoparticle density and hybrid contacts with second-order retinal neurons. The results establish the functional role of organic photovoltaic nanoparticles in restoring visual activities in fully degenerate retinas with intense inner retina rewiring, a stage of the disease in which patients are subjected to prosthetic interventions.
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