A single because of their distinctive traits, hydrogels have become the most preferred materials for biomedical applications today. Hydrogels are three-dimensional hydrophilic polymeric networks with a high water-holding capacity as well as the ability to store biological fluids. The specific structure and swelling behavior of hydrogel largely influence the water holding and biological properties. The advantageous properties of hydrogels like flexibility, versatility, stimuli-responsive and soft structure make them versatile materials for medical applications. However, extreme water content, porous nature, and smooth in consistency are closely simulated living tissue than other alternative biomaterials. Such a close resemblance of hydrogels triggers several chances in the biomedical field. Hydrogels have a wide footprint in day today products but still their significant use yet not completely explored. Hydrogels have a well-demonstrated appreciable theatrical role in wound healing, contact lenses, tissue engineering, and many hygiene products. But commercially still hydrogels have not been well-explored in tissue engineering and drug delivery. In the meanwhile, a variety of drug-delivery-related devices and scaffolds have been developed, reviewed, and a few have been patented, but few have reached the market. Here, the authors try to focus on hydrogel-based biomaterials and their applications in the healing of wounds, tissue engineering, cosmetics, drug delivery, and contact lenses. Graphical Abstract

In this study, a low-cost bioadsorbent aluminum metal blended with groundnut shell activated carbon material (Al-GNSC) was used for Cr(VI) adsorption from aqueous solutions. Al-GNSC was prepared and characterized using Fourier transform infrared spectrometer (FT-IR), scanning electron microscopic (SEM) and X-ray diffraction (XRD) to determine its surface morphology. Batch studies were performed and the optimum conditions for maximum Cr(VI) removal (of 94.2%) were found at pH 4.0, initial concentration 100 mg/L, adsorbent dosage 8 g/L of Cr(VI) solution, and time of contact 50 min. Moreover, the Langmuir isotherm model (maximum adsorption capacity of 13.458 mg/g) was the best fit and favored the mono-layered Cr(VI) adsorption. The kinetic studies reveal that the pseudo-second-order model was the best fit and favored chemisorption as the rate-limiting step. The desorption study revealed that Cr(VI) leached with sodium hydroxide solution acted as a regenerating agent. It is proved that Al-GNSC removes the Cr(VI) content in groundwater samples. The methodology developed using the Al-GNSC adsorbent as an alternative for the adsorption of Cr(VI) ions is remarkably successful in this study.

The development of flexible and wearable devices is mainly required for tactile sensing; as such devices can adapt to complicated nonuniform surfaces, they can be applied to the human body. Nevertheless, it remains necessary to simultaneously achieve small-scale, portable, and stable developments in such devices. Thus, this work aims at fabricating a novel, lightweight, ultra-flexible, and fiber-shaped coaxial structure with a diameter of 0.51 mm using polydimethylsiloxane/graphene/nylon material, based on piezoresistive and triboelectric principles. The piezoresistive-based robotic-hand-controlled sensor thus realized exhibits a response time of 120 ms and a fast recovery time of 55 ms. Further, the piezoresistive-based sensors effectively feature whisker/joystick-guided behaviors and also sense the human finger contact. Owing to the triboelectric-based self-powered nanogenerator behavior, the resulting sensor can convert mechanical motion into electrical energy, without adversely affecting human organs. Moreover, this triboelectric-based human finger sensor can be operated under different bending modes at specific angles. Notably, this multifunctional sensor is cost-effective and suitable for various applications, including robotic-hand-controlled operations in medical surgery, whisker/joystick motions in lightweight drone technology, and navigation with high-sensitivity components.