Hydrogels are a promising material for a variety of applications after appropriate functional and structural design, which alters the physicochemical properties and cell signaling pathways of the hydrogels. Over the past few decades, considerable scientific research has made breakthroughs in a variety of applications such as pharmaceuticals, biotechnology, agriculture, biosensors, bioseparation, defense, and cosmetics. In the present review, different classifications of hydrogels and their limitations have been discussed. In addition, techniques involved in improving the physical, mechanical, and biological properties of hydrogels by admixing various organic and inorganic materials are explored. Future 3D printing technology will substantially advance the ability to pattern molecules, cells, and organs. With significant potential for producing living tissue structures or organs, hydrogels can successfully print mammalian cells and retain their functionalities. Furthermore, recent advances in functional hydrogels such as photo- and pH-responsive hydrogels and drug-delivery hydrogels are discussed in detail for biomedical applications.

The challenges and demands of implant materials are changing as a result of the substantial expansion in the global population. Suitable implants are required for aged people, physical injuries, patients who need revised surgeries, contaminated implants, and accident victims. Hence, the requirement for implants is drastically increasing day by day. Metals, ceramics, and polymers are used as implant materials by biomedical industries for long-term suffering patients. Stainless steel, titanium and its alloys, aluminum alloys, cobalt, zirconium, etc. (metals), hydroxyapatite (ceramic), polyurethane, polyethylene, polyimide, etc. (polymers), are some of the examples that fulfill the implant requirements. There are many other obstructions, such as adhesion, inflammation, and bacterial attack, which minimize the implant’s performance and its activity. However, coatings on ideal implant materials are significant to avoid its failure and to enhance its durability and longevity. Advanced techniques, such as physical and chemical methods, are suitable coating approaches to promote the surface of implants with respect to mechanical, biological, and other multifunctional activities. This review paper focuses on and investigates several strategies for bioactive implants’ coatings, analysis, and emerging applications for biomedical industries.

In modern days, the usage of trauma fixation devices has significantly increased due to sports injury, age-related issues, accidents, and revision surgery purposes. Numerous materials such as stainless steel, titanium, Co–Cr alloy, polymers, and ceramics have been used to replace the missing or defective parts of the human body. After implantation, body fluids (Na⁺, K⁺, and Cl⁻), protein, and blood cells interact with the surface of metallic implants, which favours the release of ions from the metallic surface to surrounding body tissues, leading to a hypersensitive reaction. Body pH, temperature, and interaction of immune cells also cause metal ion leaching and lose host cell interaction and effective mineralization for better durability. Moreover, microbial invasion is another important crisis, which produces extracellular compounds onto the biomaterial surface through which it escapes from the antimicrobial agents. To enhance the performance of materials by improving mechanical, corrosion resistance, antimicrobial, and biocompatibility properties, surface modification is a prerequisite method in which chemical vapour deposition (CVD), physical vapour deposition (PVD), sol–gel method, and electrochemical deposition are generally involved. The properties of bioceramics such as chemical inertness, bioactivity, biocompatibility, and corrosion protection make them most suitable for the surface functionalization of metallic implants. To the best of our knowledge, very limited literature is available to discuss the interaction of body proteins, pH, and temperature onto bioceramic coatings. Hence, the present review focuses on the corrosion behaviour of different ceramic composite coating materials with different conditions. This review initially briefs the properties and surface chemistry of metal implants and the need for surface modifications by different deposition techniques. Further, mechanical, cytotoxicity, antimicrobial property, and electrochemical behaviour of ceramics and metal nitride coatings are discussed. Finally, future perspectives of coatings are outlined for biomedical applications.

The development of biocompatible nanocomposite hydrogels with effective wound healing/microbicidal properties is needed to bring out their distinguished characteristics in clinical applications. The positive interaction between graphene oxide/reduced graphene oxide (GO/rGO) and hydrogels and aloe vera gel represents a strong strategy for the advancement of therapeutic approaches for wound healing. In this study, the synthesis, characterization, and angiogenic properties of graphene-based nanocomposite gels have been corroborated and substantiated through several in vitro and in vivo assays. In this respect, graphene oxide was synthesized by incorporating a modified Hummer’s method and ascertained by Raman spectroscopy. The obtained GO and rGO were uniformly dispersed into the aloe vera gel and hydrogel, respectively, as wound healing materials. These formulations were characterized via in vitro bio-chemical techniques and were found suitable for the appropriate cell viability, attachment, and proliferation. In addition, in vivo experiments were conducted using male Wistar rats. This revealed that the GO/rGO-based gels stimulated wound contraction and re-epithelialization compared to that of the non-treatment group. From the study, it is suggested that GO/rGO-based aloe vera gel can be recommended as a promising candidate for wound healing applications.