ABSTRACT
In this work, functionalized carbon nanotubes (CNTs) using two polyamine polymers, polyethyleneimine (PEI) and polyamidoamine dendrimer (PAMAM), were investigated by thermal analysis in order to address preparation strategies to obtain low cytotoxic compounds with the ability to conjugate micro-RNAs and, at the same time, to transfect efficiently endothelial cells. Thermogravimetric analysis (TGA) was coupled to chemometrics as a novel analytical strategy to characterize functionalized CNTs from different preparation conditions. In particular, two starting materials were considered:very small CNTs and carboxylated CNTs (CNT-COOH) in order to examine the affinity with polymers. Chemometrics permitted to compare results from TGA and to investigate the effect of a number of factors affecting the synthesis of coated nanotubes including a different amount of involved polymer and the time required for the suspension for a satisfactory and reproducible preparation procedure. The results demonstrated the effectiveness of TGA as a tool able to address synthesis of coated CNTs to be employed as efficient drug delivery vectors in biomedical applications.
ABSTRACT
We studied the ultrastructural alteration of glomerular anionic sites in 6 patients with minimal change nephrotic syndrome, 5 patients with membranous glomerulonephritis, 4 patients with focal segmental glomerulosclerosis, and 4 patients with IgA nephropathy by staining with polyethyleneimine (PEI) as a cationic probe. The control study was examined by using a nephrectomy specimen of non-glomerular disease which had no proteinuria. This method seems to selectively stain heparan sulphate in the basement membranes and has been widely used to evaluate changes in basement membrane charge in various human diseases as well as in experimental studies. The anionic sites in the lamina rara interna and lamina densa of normal glomerular basement membrane were always less numerous and less regularly distributed than those in the lamina rara externa. Characteristic common findings in these glomeruli showed a marked decrease of glomerular anionic sites in the regions with immune-complex deposits and normal distribution in the regions with focally those being absorbed and newly forming glomerular basement membrane. They were not detected in the gap of the basement membrane and on the area of the detached overlying epithelium using the PEI method. But the foot process fusion of epithelial cells seems not to influence the loss of anionic sites on the glomerular basement membrane.