Abstract

Introduction

Polyacrylamide hydrogels and their polymerization

Polyacrylamide hydrogel in cell biology and drug delivery system

Classification of hydrogels: a broad overview

Homo-polymeric hydrogels

Co-polymer hydrogels

Semi-interpenetrating network

Interpenetrating network

Recent progress (2019–۲۰۲۲) of polyacrylamide-based hydrogel composites

Swelling and degradation behaviour of PAM hydrogels

Mechanical properties of PAM hydrogel composites

Tribological and rheological properties of PAM composites

Magnetic hydrogel composites

Biological properties of the PAM hydrogel composites

Applications of polyacrylamide hydrogels

Conclusions

Scope for the future work

Acknowledgements

References

Abstract

     Polyacrylamide hydrogels have made an immensely important place in various fields having bio-compatibility, high water-holding capacity, tunability and cheap synthesis, which has attracted researchers’ attention. Polyacrylamide can be chemically infused with other elements or compounds to find applications in magnetic biosensors, drug delivery, cartilage repair and wound dressing. This paper throws light on the brief introduction of hydrogels and their classification. The polymerization method of polyacrylamide hydrogel followed by its clinical uses (cell biology and drug delivery) is adorned in the report. Keeping at the centre, the recent highlights on the research work done on polyacrylamide hydrogel composites using various reinforcing additives are crucially explored first time in the present report. The improvement practice in the strength, bonding and self-healing of the polyacrylamide hydrogel is demonstrated by the encapsulation of nanoparticles like silicon, carbon nanotubes, gelatine, cellulose, etc. The clinical aspects of the polyacrylamide are corroborated by the cell viability, proliferation and migration. Thus, polyacrylamide hydrogels are emerging candidates, precisely illuminated in the review, which can be an influential highlight designed for upcoming research.

Introduction

     Hydrogels are flexible polymers with excellent biocompatibility. Due to their three-dimensional network, hydrogels have high water-holding capacity. Further, hydrogels have the ability to form blends by using more than one monomers and cross-linkers. Chemical infusion of hydrogels has also been tested with several biocompatible materials. These hydrogel composites are tested for a ‘new generational’ changes in existing applications. This infusion using corresponding salts followed by reduction using a suitable reducing agent forms nanoparticles suspended in the hydrogel. Research in magnetic bio-sensing materials has tested hydrogels infused with magnetic nanoparticles also called ferrogels. For applications like cartilage replacement as well, hydrogel-based composites are carefully prepared for specific cartilage-like properties [1, 2]. Gels are formed when crosslinker forms bonds laterally linking two polymeric chains. This is much like the two sugar phosphate DNA backbones that are joined by chromosome pairs. Except that, the polymeric chains are flexible, unlike DNA backbones! Without cross-linking, the polymeric chains will dissolve into the aqueous phase and only interaction between the chains is through a physical bond. Cross-linking also decides the strength-related properties of the gel. Optimizing the cross-linking method and the cross-linking ratio is essential for strength-related properties.

Conclusions

     Polyacrylamide hydrogels are emerging polymers due to their unique properties, which have made them useful in fields like cartilage repair, wound dressing, contact lenses, drug delivery and biosensors. The PAM hydrogel can be prepared by a monomer unit along with a cross-linker mixed in a suitable quantity. The PAM composites were fabricated by introducing some nanoparticles and reducing them to change these cations/anions into metal ions. The present review described the introduction of hydrogels with their different types, based on the polymeric network structure. The PAM hydrogels along with different nanoparticles like TiO2 and CNTs are turned with high strength ([ 0.43 and 2.340 MPa compressive strength and elastic modulus, respectively) composites. However, the puncture resistant of the PAM was also enhanced with these nanoparticles, estimated using the needle insertion technique. The tribological and magnetic investigations (magnetic saturation 1.41 emu/g) revealed an improved performance of PAM with encapsulation of nanoparticles due to the fine-grained structure and lubrication effects (created by CNTs). Furthermore, the biological activity of PAM composites was remarkably important and ideal for the implementation in biomedical research. Thus, in short, this review report is an important highlight for PAM hydrogel composites and can provide a prominent direction to future research based on the PAM hydrogels for biomedical applications.