Disulfide-functionalized hyperbranched poly(amido amine)s (HPAMAMs) were synthesized by Michael addition polymerization of N,N'-cystaminebisacrylamide and 1-(2-aminoethyl)piperazine. The novel HPAMAMs displayed bright fluorescence, and the emissions bands cover nearly the whole visible wavelength range. When polymer solutions were excited at 330-385, 460-490, and 510-550 nm, blue, green, and red solutions were observed, respectively. The HPAMAMs are biodegradable and they can be easily cleaved by 2-mercaptoethanol or glutathione, leading to a decrease in the fluorescence intensity. Studies of applications of the biocompatible and biodegradable HPAMAMs in fluorescence imaging technology and biological science are in progress.
A water-soluble, biodegradable and fluorescent hyperbranched poly(amidoamine) with mannose groups on their surface (M-HPAMAM) has been successfully prepared, and the synthetic strategy includes Michael addition polymerization of diacrylamide with 1-(2-aminoethyl)piperazine and, subsequently, surface modification with mannosamine. The photoluminescence of M-HPAMAM was enhanced significantly due to the surface mannose groups. Incubation of E. coli with M-HPAMAMs yielded brightly fluorescent bacteria clusters, but the fluorescent intensity of the aqueous solution lowered. This indicates that the M-HPAMAMs have strong affinity with bacteria due to their polyvalent interactions. Based on the size and the amount of bacteria clusters formed, the bacteria with the concentrations higher than 10(2) cfu/mL can be detected.
The hyperbranched poly(amido amine) nanoparticles (HPAMAM NPs) with multiple functions, such as biodegradability, autofluorescence, and specific affinity, were successfully prepared by Michael addition dispersion polymerization of CBA, AEPZ, and N-galactosamine hydrochloride (or N-glucosamine hydrochloride) in a mixture of methanol/water. The resultant NPs displayed strong photoluminescence, high photostability, broad absorption, and emission (from 430 to 620 nm) spectra. The fluorescence from HPAMAM NPs may be attributed to the tertiary amine chromophore. The incubation results of the liver cancer cells, HepG2, with the NPs showed that the NPs are nontoxic and can be recognized by asialoglycoprotein receptors on the surface of HepG2 and then can be internalized. Therefore, they have potential applications in bioimaging and drug or gene delivery.
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