Donor shortage for organ transplantations is a major clinical challenge worldwide. Potential risks inevitably encountered with traditional methods include complications, secondary injuries, and, most importantly, limited donor sources. Today, researchers from multiple disciplinary areas, including biomaterials, biology, and nanotechnology in tissue engineering, attempt to bio-fabricate virtually every human tissue or organ. Tissue engineering techniques generally require the use of a porous scaffold, which serves as a three-dimensional template for initial cell attachment and subsequent tissue formation both in vitro and in vivo. The scaffold provides the necessary support for cells to attach, grow, proliferate, and maintain their differentiated function. This article represents a concise summary of different procedures for fabricating sponge-like and fibrous scaffolds using a variety of technologies. First, we will discuss different approaches that allow us to create fibers, which have long been recognized as the primary constituent in 3D scaffolds. These methods include electrospinning and microfluidic-based methods, among others. Following that, the various techniques for fabricating 3D scaffolds, ranging from simple to complex structures, as well as evaluating their advantages and disadvantages, will be explored. Graphical Abstract

Even at low levels heavy metal pollutants significantly threaten the quality of life, posing long-term risks. Current laboratory instrument-based measurement techniques have their limitations due to lengthy preparation and analysis steps. In this study, we introduce a screen-printed electrochemical sensor utilizing non-toxic, biodegradable sodium alginate grafted with 2-acrylamido-2-methyl propane sulfonic acid (AMPS) and conductive fillers for a trace-level lead ion detection in water. The presence of anionic functional groups facilitates chelation through electrostatic interactions, enabling them to preferentially bind to positive lead ions. With the proposed sensor, a low detection limit of 0.1 ppb was obtained by square wave anodic stripping voltammetry. This work demonstrates the effectiveness of an eco-friendly, sustainable sensor construct that takes advantage of enhanced organo-metallic interactions.

We present a novel miniaturized, gear-shaped, fuel-free actuator capable of autonomously propelling itself in an aquatic environment to absorb heavy metals, such as copper ions. While hydrogel-based absorbents are promising solutions for cationic pollutant remediation, their stationary nature limits their effectiveness in areas where contaminants are unevenly distributed. To address this, we developed a bio-inspired soft actuator that mimics natural propulsion mechanisms. The Marangoni effect, driven by its inherent chemical properties, demonstrated a self-propelled motion without requiring external fuel. The proof-of-concept actuator generated a plane motion lasting up to 2 h and swept over an area approximately 400 times bigger than its size. By harnessing the chemical and optical properties of the hydrogel, we efficiently removed and quantitatively analyzed copper ions through a colorimetric method. This innovative integration of self-propelled movement and efficient copper ion absorption underscores its potential for advancing miniaturized devices in environmental remediation, paving the way for more active and efficient pollutant removal systems in challenging aquatic environments.

We present a novel self-powered ultraviolet (UV) sensor using edible materials for food packaging applications. As urbanization takes place on a global scale, the general public's reliance on packaged food increases rapidly. To reduce food loss in the supply chain, environmental conditions where food products are exposed need to be monitored carefully. UV light can induce chemical changes in perishable foods, and UV sensors can detect such changes to warn of potential food spoilage, ensuring food safety for consumers. Most of the developed UV sensors are made of non-food grade materials, which do not bio-degrade and become another source of pollution if not disposed of properly. In addition, the dependency of sensors on external power sources limits their applicability in food packaging. We present a flexible UV sensor using a substrate of ethyl cellulose created by evaporating a solution of ethanol and ethyl cellulose. The sensor incorporates stacked interdigitated electrodes with an algae-based electrolyte and ZnO layer as the UV absorbent material, demonstrating the novel use of organic materials in UV detection. The fabricated device works in a photovoltaic mode; the results revealed that the sensor can detect UV changes without applying external bias under a 365 nm centered laser radiation.

This study presents a novel UV dose sensor for intelligent food packaging, constructed using laser-induced graphene (LIG) and sustainable materials, for rapid and cost-effective measurements of both instantaneous and cumulative UV exposure. Integrating an ionochromic cell with a blueberry-based organic electrolyte enables it to retain the time-exposure information. This unique feature enables the sensor to memorize and visually display the degree of UV irradiation, a critical function for tracing the external conditions to which packaged food has been subjected. The device achieves exceptional sensitivity of ~ 1000%, without requiring batteries. This work provides a sustainable, efficient, and scalable solution for ensuring food safety.