Volume change of double cross-linked poly(aspartic acid) hydrogels induced by cleavage of one of the crosslinks.

In the present paper we report for the first time the development of redox-responsive biocompatible polymer gels. Double cross-linked poly(aspartic acid) hydrogels were prepared using two different cross-linking agents simultaneously. One of the cross-linkers was diaminobutane (DAB), the other cystamine (CYS).

A novel potentiometric method for the determination of real crosslinking ratio of poly(aspartic acid) gels.

In order to obtain nontoxic functional polymer gels for biomedical applications, chemically crosslinked poly(aspartic acid) gels have been prepared using 1,4-diaminobutane as crosslinker. The presence of COOH and amino groups on the network chains renders these gels pH sensitive. Due to the specific hydrophobic-hydrophilic balance, these gels show a significant volume transition at a well-defined pH close to the pK value of uncrosslinked poly(aspartic acid).

Synthesis and swelling properties of novel pH-sensitive poly(aspartic acid) gels.

Chemically cross-linked poly(aspartic acid) (PASP) gels were prepared by the hydrolysis of poly(succinimide) (PSI). The latter was prepared by thermal polycondensation of aspartic acid. The PSI chains were cross-linked by natural amines and amino acid derivatives such as putrescin, spermine, spermidine, lysine and cystamine to obtain biodegradable, biocompatible, amino acid-based hydrogels.

[Controlled drug delivery systems. Paradigm change in pharmacology].

This article is to introduce the readers in the colourful world of controlled drug delivery. These structures are to carry the drug into the place of release for let it there out with proper velocity. So the aim of the researches are not to find the best drug, but to get it into the right place in the right time.