The field of three dimensional (3D) bioprinting has witnessed significant advancements, with bioinks playing a crucial role in enabling the fabrication of complex tissue constructs. This review explores the innovative bioinks that are currently shaping the future of 3D bioprinting, focusing on their composition, functionality, and potential for tissue engineering, drug delivery, and regenerative medicine. The development of bioinks, incorporating natural and synthetic materials, offers unprecedented opportunities for personalized medicine. However, the rapid technological progress raises regulatory challenges regarding safety, standardization, and long-term biocompatibility. This paper addresses these challenges, examining the current regulatory frameworks and the need for updated guidelines to ensure patient safety and product efficacy. By highlighting both the technological potential and regulatory hurdles, this review offers a comprehensive overview of the future landscape of bioinks in bioprinting, emphasizing the necessity for cross-disciplinary collaboration between scientists, clinicians, and regulatory bodies to achieve successful clinical applications.

This paper describes the potential of carbon dot nanocomposites (CDs) synthesized from waste materials by top-down and bottom-up state-of-the-art approaches. Through sustainable practices, wastes are converted into valuable nanomaterials, solving environmental problems and pioneering advances in nanotechnology. In this paper, an overview of the synthesis aspects of CDs is presented with the formation of their versatile nanocomposites and metal/metal oxide elements. The phase of this paper has been devoted to elaborate study of the multifaceted applications of CDs in various sectors, ranging from electronics and biomedicine to environmental remediation. Although having huge potential, CDs application is presently hampered due to limitations on scalability, stability, and reproducibility. In this review paper, most profound insights have been drawn into overcoming these barriers for clear routes toward future innovations. The present research being undertaken in this area has, therefore, underscored sustainable nanotechnology to resolve global problems and achieving technological development through green synthesis. Necessitating the efficient sewage disposal systems ensuring minimum toxin generation. Graphical abstract

Fabrication of functional organs is the holy grail of tissue engineering and the possibilities of repairing a partial or complete liver to treat chronic liver disorders are discussed in this review. Liver is the largest gland in the human body and plays a responsible role in majority of metabolic function and processes. Chronic liver disease is one of the leading causes of death globally and the current treatment strategy of organ transplantation holds its own demerits. Hence there is a need to develop an in vitro liver model that mimics the native microenvironment. The developed model should be a reliable to understand the pathogenesis, screen drugs and assist to repair and replace the damaged liver. The three-dimensional bioprinting is a promising technology that recreates in vivo alike in vitro model for transplantation, which is the goal of tissue engineers. The technology has great potential due to its precise control and its ability to homogeneously distribute cells on all layers in a complex structure. This review gives an overview of liver tissue engineering with a special focus on 3D bioprinting and bioinks for liver disease modelling and drug screening.

Volumetric additive manufacturing (VAM) is revolutionizing the field of cell printing by enabling the rapid creation of complex three-dimensional cellular structures that mimic natural tissues. This paper explores the advantages and limitations of various VAM techniques, such as holographic lithography, digital light processing, and volumetric projection, while addressing their suitability across diverse industrial applications. Despite the significant potential of VAM, challenges related to regulatory compliance and scalability persist, particularly in the context of bioprinted tissues. In India, the lack of clear regulatory guidelines and intellectual property protections poses additional hurdles for companies seeking to navigate the evolving landscape of bioprinting. This study emphasizes the importance of collaboration among industry stakeholders, regulatory agencies, and academic institutions to establish tailored frameworks that promote innovation while ensuring safety and efficacy. By bridging the gap between technological advancement and regulatory oversight, VAM can unlock new opportunities in regenerative medicine and tissue engineering, transforming patient care and therapeutic outcomes.

Three-dimensional (3D) bioprinting is a versatile technique for biomedical applications, and includes organ printing, 3D disease model development, and drug delivery. The bioprintable materials combined with live cells have been utilized as bioinks in 3D bioprinter to fabricate versatile 3D printed structures. The 3D structures developed with smart and responsive materials can change their dimension, a technique similar to self-assembly, unfolding a new branch termed as four-dimensional (4D) printing. This manuscript reviews the details of various bioprintable materials and 3D printers, the application of 3D printing in biomedicine, smart materials, and stimulations for 4D printing. Further, this article also summarizes the regulatory issues and the limitations involved with the bioprinting. The advancements in 3D and 4D printing technology have significantly contributed to the medical field, and adequate research and amalgamation of engineering and science ideas will strengthen the application of this technology and bring solution for the existing problems. Graphical abstract

Three-dimensional bioprinting is an emerging technology that has high potential application in tissue engineering and regenerative medicine. Increasing advancement and improvement in the decellularization process have led to an increase in the demand for using a decellularized extracellular matrix (dECM) to fabricate tissue engineered products. Decellularization is the process of retaining the extracellular matrix (ECM) while the cellular components are completely removed to harvest the ECM for the regeneration of various tissues and across different sources. Post decellularization of tissues and organs, they act as natural biomaterials to provide the biochemical and structural support to establish cell communication. Selection of an effective method for decellularization is crucial, and various factors like tissue density, geometric organization, and ECM composition affect the regenerative potential which has an impact on the end product. The dECM is a versatile material which is added as an important ingredient to formulate the bioink component for constructing tissue and organs for various significant studies. Bioink consisting of dECM from various sources is used to generate tissue-specific bioink that is unique and to mimic different biometric microenvironments. At present, there are many different techniques applied for decellularization, and the process is not standardized and regulated due to broad application. This review aims to provide an overview of different decellularization procedures, and we also emphasize the different dECM-derived bioinks present in the current global market and the major clinical outcomes. We have also highlighted an overview of benefits and limitations of different decellularization methods and various characteristic validations of decellularization and dECM-derived bioinks.