Aptamer-gelatin composite for a trigger release system mediated by oligonucleotide hybridization

Abstract

Nucleic acid aptamers not only specifically bind to their target proteins with high affinity but also form intermolecular hybridization with their complementary oligonucleotides (CO). The hybridization can interrupt aptamer/protein interaction due to the changes of aptamer secondary structure which rely on hybridization length and base-pairing positions. Herein we aim to use this unique property of the aptamers, when combined with gelatin to develop a novel composite with desirable protein release profiles. Platelet-derived growth factor-BB (PDGF-BB) and its aptamer were used as target molecules. Prior to performing the release study, the effects of CO on aptamer-protein interaction were observed by surface plasmon resonance (SPR). The SPR sensorgram indicated that the aptamer dissociated from the bounded proteins when it hybridized with the CO. The aptamer was then immobilized onto streptavidin coated polystyrene particles via biotin/streptavidin interaction. Then, PDGF-BB and aptamer functionalized particles were mixed with gelatin solution and cast as small pieces of composite. The success of the composite preparation was confirmed by flow cytometry and microscopy. PDGF-BB release at several time points was quantified by ELISA. The results showed that the aptamer-gelatin composite could slow the release rate of the proteins from the composite due to strong binding of proteins and aptamers. Once the CO was added to the system, the release rate was significantly enhanced because the aptamer hybridized with the CO and lost its active secondary structure. Therefore, the proteins were triggered to release out from the composite. This work suggests a promising strategy for controlling the release of bioactive molecules in medical treatments.

Keywords:

• gelatin
• aptamers
• composites
• hybridization
• triggered release

Acknowledgments

The authors thank Dr Sitthisuntorn Supothina for the support of lab equipment, Dr C. Vijaya Kumar for technical support in using the SPR instrument, and Mr Sermkieat Tanucchit for technical support on flow cytometry measurement. The authors also thank Mr John Winward for editing the manuscript.

Additional information

Funding

Funding. This work was granted by a Research Grant for New Scholar supported by the Office of Higher Education Commission, the Thailand Research Fund and the Thammasat University (MRG5580187).