CdS nanoparticles: structural and energetical correlations

It is well known that the quantum confinement effects are closely related to the existence of different behavior for the same material composition. Due to the reduced size scale of the nanoparticles, the most part of their forming atoms are at the particle surface, which needs to be as stable as possible, to avoid phenomena such as dissolution and photodegradation. This way, methodologies for semiconductor nanoparticles obtention shall take into account the size, shape and energy of the final product. However, the relationship between these parameters is not yet clearly understood for nanometric systems, specially for those ones which are smaller than 20nm. In this work, we present and discuss experimental and theoretical data obtained for nanoparticles of the semiconductor cadmium sulfide (CdS), in order to contribute for the understanding of the correlation between energetical and structural properties of nanometric systems in the quantum confinement regime. (C) 2004 Elsevier B.V. All rights reserved.891212

Fluorescent II-VI semiconductor quantum dots in living cells: Nonlinear microspectroscopy in an optical tweezers system

In this work we used a setup consisting of an optical tweezers combined with a nonlinear microspectroscopy system to perform scanning microscopy and obtain emission spectra using two photon excited (TPE) luminescence of captured single living cells labeled with core-shell fluorescent semiconductor quantum dots (QDs). The QDs were obtained via colloidal synthesis in aqueous medium with an adequate physiological resulting pH. Sodium polyphosphate was used as the stabilizing agent. The results obtained show the potential presented by this system as well as by these II-VI fluorescent semiconductor quantum dots to perform spectroscopy in living trapped cells in any neighborhood and dynamically observe the cell chemical reactions in real time.11292734273

Core-shell CdS/Cd(OH)(2) quantum dots: synthesis and bioconjugation to target red cells antigens

We report a new and efficient methodology of labelling red blood cells, in order to investigate the expression of anti-A antigen, employing luminescent semiconductor nanocrystals. Highly luminescent and stable core-shell cadmium sulphide/cadmium hydroxide [CdS/CdS(OH)(2)] colloidal particles were obtained in the nanometre size range. The surface of these particles was characterized by using a monoclonal anti-A antibody via a one-step glutaraldehyde cross-linking procedure, followed by conjugation of the particles to red cells of blood groups A(+), A(2)(+) and O+. Laser scanning confocal microscopy images indicated that after conjugation for 30 min, A(+) and A(2)(+) erythrocytes presented different patterns of dual bright emission whereas the O+ group cells showed no emission. We suggest that this labelling procedure may be applied as a quantitative tool to investigate the distribution and expression of alloantigen in red blood cells.219310310

Investigation of red blood cell antigens with highly fluorescent and stable semiconductor quantum dots

We report a new methodology for red blood cell antigen expression determination by a simple labeling procedure employing luminescent semiconductor quantum dots. Highly luminescent and stable core shell cadmium sulfide/cadmium hydroxide colloidal particles are obtained, with a predominant size of 9 nm. The core-shell quantum dots are functionalized with glutaraldehyde and conjugated to a monoclonal anti-A antibody to target antigen-A in red blood cell membranes. Erythrocyte samples of blood groups A(+), A(2)(+), and O+ are used for this purpose. Confocal microscopy images show that after 30 min of conjugation time, type A(+) and A(2)(+) erythrocytes present bright emission, whereas the O+ group cells show no emission. Fluorescence intensity maps show different antigen expressions for the distinct erythrocyte types. The results obtained strongly suggest that this simple labeling procedure may be employed as an efficient tool to investigate quantitatively the distribution and expression of antigens in red blood cell membranes. (C) 2005 Society of Photo-Optical Instrumentation Engineers.10

Highly fluorescent semiconductor core-shell CdTe-CdS nanocrystals for monitoring living yeast cells activity

Fluorescent semiconductor nanocrystals in quantum confinement regime (quantum dots) present several well-known features which make them very useful tools for biological labeling purposes. Low photobleaching rates, high chemical stability and active surface allowing conjugation to living cells explain the success of this labeling procedure over the commonly used fluorescent dyes. In this paper we report the results obtained with highly fluorescent core-shell CdTe-CdS (diameter=3-7 nm) colloidal nanocrystals synthesized in aqueous medium and conjugated to glucose molecules. The conjugated nanocrystals were incubated with living yeast cells, in order to investigate their glucose up-take activity in real time, by confocal microscopy analysis.89495796

Optical tweezers for studying taxis in parasites

In this work we present a methodology to measure force strengths and directions of living parasites with an optical tweezers setup. These measurements were used to study the parasites chemotaxis in real time. We observed behavior and measured the force of: (i) Leishmania amazonensis in the presence of two glucose gradients; (ii) Trypanosoma cruzi in the vicinity of the digestive system walls, and (iii) Trypanosoma rangeli in the vicinity of salivary glands as a function of distance. Our results clearly show a chemotactic behavior in every case. This methodology can be used to study any type of taxis, such as chemotaxis, osmotaxis, thermotaxis, phototaxis, of any kind of living microorganisms. These studies can help us to understand the microorganism sensory systems and their response function to these gradients.134S