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Published online: 17 December 2008 | doi:110.1038/nchina.2008.297

DNA hydrogels: Fishy fluorescence

Felix Cheung

Introduction

© (2008) RSC

DNA is a remarkable polymer. Apart from being the building block of life, it can also be made into hydrogels that serve a wide range of applications, including drug delivery, tissue engineering and biosensors. So far, no fluorescent DNA hydrogel has been developed except for those that are stained with fluorescent dyes. Shu Wang and co-workers at the Chinese Academy of Sciences in Beijing¹ have prepared fluorescent DNA hydrogels from salmon DNAs and conjugated polymers — a first of its kind.

The researchers added polyphenylene vinylene (PPV) into alkaline aqueous solution at room temperature to yield positively charged sulphonium precursors of PPV (SP–PPV), which can crosslink DNAs by electrostatic interactions. They then polymerized the precursor monomers in a mixture of salmon DNAs, dimethyl sulphoxide, alkaline and water to yield the fluorescent DNA composite hydrogel (pictured).

The fluorescent DNA hydrogel is water compatible. In its dried form, it can absorb water more than 300 times its own mass. Moreover, the hydrogel's fluorescence decreases as it absorbs more water content.

The researchers were therefore inspired to use the hydrogel as a platform for monitoring drug release. They found that when the hydrogel was loaded with nicardipine hydrochloride (a drug used for treating hypertension), its fluorescence was quenched. As the hydrogel slowly released nicardipine hydrochloride in a slightly acidic environment, its fluorescence was recovered. The researchers conclude that these DNA hybrid hydrogels are a new class of materials that can be exploited in the biomedical field, such as monitoring drug loading and release by fluorescence technique.

The authors of this work are from:
Beijing National Laboratory for Molecular Science, Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing, China.

Reference

1. Tang, H. et al. Fluorescent DNA–poly(phenylenevinylene) hybrid hydrogels for monitoring drug release. Chem. Commun. doi:10.1039/b817788k (2008). | Article |