Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 2 de 2
Filter
Add more filters










Database
Language
Publication year range
1.
J Colloid Interface Sci ; 442: 89-96, 2015 Mar 15.
Article in English | MEDLINE | ID: mdl-25521554

ABSTRACT

We assessed a method for the preparation of small, highly stable and unprotected Pd nanoparticles by picosecond laser ablation in 2-propanol. The nanoparticles can be extracted from 2-propanol by centrifugation and redispersed in water, where a strongly negative ζ-potential assures long term stability. The proposed procedure permits reduction of particle size down to 1.6nm and optimization of the Pd(0):Pd(II) ratio which, in the best cases, was of the order of 6:1. The increase of this ratio with ablation times has been correlated to the high temperature conversion of PdO to metallic Pd by a simple theoretical model. A study of the relationship between colloid absorption at 400nm and Pd concentration permitted the role of PdO in the determination of the UV-vis spectra to be clarified and the limits of the Mie theory for the evaluation of colloid concentration to be established. The absorption at 400nm can be used as a fast method to estimate the Pd content in the colloids, provided that a calibration of the ablation process is preliminarily performed.

2.
J Colloid Interface Sci ; 407: 89-94, 2013 Oct 01.
Article in English | MEDLINE | ID: mdl-23871312

ABSTRACT

We obtained chitosan-protected Au/Ag nanocages (NCs), i.e., hollow and porous metallic nanoparticles, by galvanic replacement reaction. Subsequently, we functionalized the NCs with a fluorescent derivative of 4-methoxy-1,8-naphtalimide (NAFTA6). The plasmonic properties of these structures, which exhibit an extinction maximum in the 700-800 nm range, allowed their use as SERS active substrates for excitation at 785 nm and an efficient identification of the vibrational bands of NAFTA6, in spite of the low ligand concentration (<10(-5) M). Furthermore, NAFTA6 could also be identified from its fluorescence emission. The proposed functionalization with fluorescent compounds opens the way to the application of metal NCs using double-wavelength detection. Namely, Raman spectroscopy in the near infrared and fluorescence emission in the visible region, with considerable potential especially for in vivo medical applications, as the plasmonic band is centered in the visible light region where biological fluids and tissues are transparent.

SELECTION OF CITATIONS
SEARCH DETAIL
...