Recent advances on small molecular gels: formation mechanism and their application in pharmaceutical fields

ABSTRACT

Introduction

As an essential complement to chemically cross-linked macromolecular gels, drug delivery systems based on small molecular gels formed under the driving forces of non-covalent interactions are attracting considerable research interest due to their potential advantages of high structural functionality, lower biological toxicity, reversible stimulus–response, and so on.

Area covered

The present review summarizes recent advances in small molecular gels and provides their updates as a comprehensive overview in terms of gelation mechanism, gel properties, and physicochemical characterizations. In particular, this manuscript reviews the effects of drug-based small molecular gels on the drug development and their potential applications in the pharmaceutical fields.

Expert opinion

Small molecular-based gel systems, constructed by inactive compounds or active pharmaceutical ingredients, have been extensively studied as carriers for drug delivery in pharmaceutical field, such as oral formulations, injectable formulations, and transdermal formulations. However, the construction of such gel systems yet faces several challenges such as rational and efficient design of functional gelators and the great occasionality of drug-based gel formation. Thus, a deeper understanding of the gelation mechanism and its relationship with gel properties will be conducive to the construction of small molecular gels systems and their future application.

KEYWORDS:

• Small molecular gel
• gelation mechanism
• gel properties
• gel elimination
• drug delivery

Article highlights

• The article provides a comprehensive overview on the formation mechanisms of small molecular gels.

• For drug-based small molecular gels, the gel characteristics can be utilized for the construction of novel carrier-free drug delivery systems.

• The gelation behavior of drugs may pose negative effects on the development of solid dosage forms, and the gel elimination strategies of drugs are summarized for the first time in this review.

• The faced challenges are pointed out, and perspectives are proposed for small molecular gel systems.

This box summarizes key points contained in the article.

Declaration of Interests

The authors declare no conflicts of interest.

Additional information

Funding

This research was supported by the National Natural Science Foundation of China (82074029, 82104401, 82274217, and 82204636), the Natural Science Foundation of Jiangsu Province (SBK2020042291), China Postdoctoral Science Foundation Funded Project (2021M693517), Project of China Pharmaceutical University (3342100010, 2632021ZD15), and Postgraduate Research & Practice Innovation Program of Jiangsu Province (3322200046).