# Synthesis and Characterization of Bioactive Oligoitaconates with Amino Acid Functional Groups for Tissue Engineering

## TL;DR

This paper explores modifying polymers with amino acids to improve their suitability for tissue engineering applications.

## Contribution

The study demonstrates efficient grafting of L-cysteine and NAC onto oligoitaconates and evaluates their physicochemical properties for tissue engineering.

## Key findings

- Thio-Michael addition of Cys and NAC onto oligoitaconates achieved high addition efficiency.
- The adducts showed thermal stability up to 200 °C and varied solubility depending on the polymer backbone.
- Low molecular weight limits standalone use but suggests potential as modifiers for scaffolds.

## Abstract

Improving the hydrophilicity and tissue adhesion of polymers remains a significant challenge in tissue engineering and is often addressed by introducing functional groups that enhance polymer–tissue interactions. In this field, L-cysteine (Cys) and N-acetyl-L-cysteine (NAC) are particularly interesting due to their functional carboxyl and amine groups, which are prone to hydrogen bonding. Following this trend, this study (i) investigated the feasibility of grafting Cys or NAC onto the linear oligoitaconates via thio-Michael addition and (ii) examined the influence of amino acid incorporation on the material’s physicochemical properties. NMR-based calculations confirmed nearly 100% addition efficiency for Cys and a slightly lower, but still high, efficiency for NAC. FT-IR spectra confirmed thiol-based addition, as signal from the Cys/NAC S–H stretching vibrations was not observed in the adduct’s spectra. The obtained adducts showed thermal stability up to 200 °C and glass transition temperatures below −20 °C. They were soluble in common organic solvents, except for Cys adducts with oligo(propylene itaconate) and oligo(hexylene itaconate), which were water-soluble only. Due to the low molecular weight (below 1000 g/mol) of oligoitaconates, their adducts cannot serve as standalone scaffold components. However, they showed potential for use as modifiers for high-molecular-weight polylactide or poly(ɛ-caprolactone)-based scaffolds.