Thermosensitive Nanospheres with a Gold Layer Revealed as Low-Cytotoxic Drug Vehicles

Abstract

In this paper, the positive effect of a gold layer on cell viability is demonstrated by examining the results given by 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfop henyl)-2H-tetrazolium (MTS) assay and two-color cell fluorescence viability (TCCV) assay. These cytotoxicity tests were performed with human cervical adenocarcinoma cells (HeLa cell line) and transformed African green monkey kidney fibroblast cells (Cos-7 cell line). To fabricate the nanostructures as drug vehicles, first, poly(l,l-lactide-co-ethylene glycol) (PLLA-PEG) and poly(N-isopropylacrylamide-co-D,D-lactide) (PNIPAAm-PDLA) were synthesized, and then two kinds of thermosensitive nanospheres comprising "shell-in-shell" structures without a gold layer (PLLA-PEG@PNIPAAm-PDLA) and with a gold layer (Au@PLLA-PEG@PNIPAAm-PDLA) were constructed by a modified double-emulsion method (MDEM). Both of them displayed a unique thermosensitive character exhibiting the lower critical solubility temperature (LCST) at 36.7 degrees C which was confirmed by UV-vis spectroscopy and differential scanning calorimetry (DSC). The release profiles of entrapped bovine serum albumin (BSA) were monitored at 22 and 37 degrees C, respectively, to reveal the thermal dependence on the release rate. In cell viability tests, both PLLA-PEG@PNIPAAm-PDLA and Au@PLLA-PEG@PNIPAAm-PDLA showed excellent cell viability, and furthermore, Au@PLLA-PEG@PNIPAAm-PDLA, particularly at high doses, exhibited more enhanced cell viability than PLLA-PEG@PNIPAAm-PDLA. This effect is mainly attributed to the gold layer which binds the protein molecules first and consequently facilitates transmembrane uptake of essential nutrients in the cell media, resulting in favorable cell proliferation.

Dual targeting strategy of magnetic nanoparticle-loaded and RGD peptide-activated stimuli-sensitive polymeric micelles for delivery of paclitaxel

“…We addressed the issues of waterinsolubility of oleic acid (OA)-stabilized SPIONs and low incorporation efficiency of hydrophobic PTX with SPION nanocarriers by using an amphiphilic polymer poly[(N-isopropylacrylamide-r-acrylamide)-b-L-lactic acid] (PNAL) as micelle-forming materials. PNAL, as previously reported, above certain concentration, is capable of forming micelle-like nanostructures in water (Jo et al 2004a;Qin et al 2005). The hydrophobic PLLA segments form aggregates inside the micelles in which carboxylic acid stabilized-SPIONs and small hydrophobic drugs can incorporate, while the hydrophilic PNA interacts with aqueous environment.…”

“…There is a distinguished peak appearing at 1540 cm -1 attributed to the amide II vibration. The peak at 1460 cm -1 is assigned to the vibration mode of methyl group, the two peaks at 1390 and 1370 cm -1 correspond to the isopropyl groups (Qin et al 2005). Two sharp peak which appeared at 1648 and 1622 cm -1 , were assigned to C=O stretching mode.…”

“…Two sharp peak which appeared at 1648 and 1622 cm -1 , were assigned to C=O stretching mode. In the spectrum of PNAL, a new sharp peak that can be assigned to carbonyl stretching appeared at 1760 cm -1 , and peaks at 1,130 and 1100 cm -1 can be assigned to the C-O stretching mode (Jo et al 2004a;Qin et al 2005). In OA-SPIONs spectra, two bands appearing at 1737 and 1711 cm -1 are assigned to C=O stretching bands of monomer and dimmer OA, respectively.…”

Polymeric/Inorganic Multifunctional Nanoparticles for Simultaneous Drug Delivery and Visualization

“…The reaction was carried out at 110 °C for 12 hours with constant magnetic stirring. Upon completion of the reaction, polymer was collected by precipitating against an excess volume of cold diethyl ether and filtered before drying in vacuum overnight [1]. Iron oxide nanoparticles (SPION) were prepared by thermal decomposition of iron oleate in a high boiling point solvent (1-octadecene) through an earlier reported two-step method [4,10].…”

“…Nanoparticles, in particular, have been developed for advanced applications in the biomedical area, i.e. for drug delivery [1], diagnostic tools improvement [2], biomolecules separations [3] and enhanced contrast imaging of different types [4]. Nowadays the focus is shifted into combining and integrating different functionalities into a single entity at a nanometer scale to allow simultaneous diagnostic, drug delivery, imaging and so on [5].…”