Abstract
Recently the area of bioimaging has benefited from new types of image enhancing agents such as quantum dots, carbon nanotubes and other nanoparticles. Cellular or even molecular level resolution has been achieved with different techniques during these last years (i.a. Fluorescence microscopy, PET/CT scan, AFM). Optical Coherence Tomography (OCT) as an imaging technique should also profit from newly developed probes. In this work we explored the tunable properties of different types of nanoparticles as contrast enhancers in OCT applications. We mainly studied the development and characteristics of metallic nanoparticles with tunable properties: gold nanoshells made of a silica core coated with a gold shell. Nanoshell and nanoparticles processing techniques are discussed, as well as their optimization for designing particles with specific absorption and scattering characteristics, and its use in OCT imaging.

Abstract
A technique for the fabrication of luminescence-based fiber-optic optrodes with multiple analyte sensitivity is proposed. Combination of photosensitive polymers doped with different luminescent indicators enabled the production of fiber probes, by self-guiding photo-polymerization, with different geometries and sensing capabilities. Results demonstrating the method flexibility are shown with luminescent probes doped with CdSe/ZnS quantum dots and an organometalic ruthenium complex for simultaneous detection of oxygen and temperature.

Abstract
Semiconductor nanocrystals have unique optical properties that make them promising alternatives to traditional dyes in many luminescence based analytical techniques. An overview of the more relevant progresses in the application of quantum dots (QDs) as analytical probes in optical fibre sensing and imaging application will be addressed. Experimental results regarding the use of QDs as self-referenced multiplexed probes for chemical sensing and analytical imaging will be presented.

Abstract
Silica based nanostructured composite materials doped with luminol and cobalt(II) ion were synthesized and characterized, resulting in a highly chemiluminescent material in the presence of hydrogen peroxide. A detection system with the CL light guided from the reaction tube to the photomultiplier tube using a one millimeter glass optical fiber was developed and assessed. A linear response was observed using a semi-logarithm calibration between 50-2000M hydrogen peroxide with 1M as the limit of detection.

Abstract
CdTe quantum dots (QDs), capped with mercaptopropionic acid (MPA), were synthesized and the variation of their fluorescence properties (steady state and lifetime)with pH was assessed in solution and when immobilized in a sol-gel host Three different sizes of CdTe QDs with excited state lifetimes ranging from 42 to 48 ns and with emission maximum at 540 nm (QD(540)). 580 nm (QD(580)) and 625 nm (QD(625)) were selected The solution pH affects the maximum emission wavelength (shifts to higher wavelengths of 23, 24 and 27 nm for QD(540), QD(550) and QP(625), respectively), the excited state lifetime and the fluorescence intensity in a reversible way. Linearization of the maximum emission wavelength variation with the pH allows the estimation of an apparent ionization constant (pK(a)) for each QD: 6.5 +/- 0.1 (QD(540)), 6.1 +/- 0.5 (QD(580)) and 5.4 +/- 0.3 (QD(625)) The variation of the QDs fluorescence properties was further explored using confocal laser scanning microscopy allowing the implementation of a new calibration method for pH imaging in solution QDs were successfully immobilized on the tip of an optical fiber by dip-coating using sal-gel procedure The immobilized QDs showed a similar pH behaviour to the one observed in solution and an apparent lifetime of 80,68 and 99 ns, respectively. The proposed QDs based methodology can be successfully used to monitor pH using wavelength encoded data in imaging and fiber optic sensing applications.

Abstract
A brief review on biconical tapered fiber sensors for biosensing applications is presented. A variety of configurations and formats of this sensor have been devised for label free biosensing based on measuring small refractive index changes. The biconical nonadiabatic tapered optical fiber offers a number of favorable properties for optical sensing, which have been exploited in several biosensing applications, including cell, protein, and DNA sensors. The types of these sensors present a low-cost fiber biosensor featuring a miniature sensing probe, label-free direct detection, and high sensitivity. © The Author(s) 2012.