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

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.

Owing to the success of three-dimensional (3D) printing in biomedical applications, the latest addition to the technology is four-dimensional (4D) printing, which has gained tremendous interest since 2012. 4D printing is being considered as an upgradation and extension of 3D that includes time as a fourth dimension with the utilization of smart biomaterials, and upon the application of any external stimulus, the shape and size of the printed structure change with time. In this review, we highlight the basic techniques involved in 4D printing, the shape memory effect, and various stimuli like light, temperature, pH, etc., that cause the shape change, leading to the transformation of the structures fabricated. 4D printing using smart materials demonstrates shape memory property and their possible applications in the field of biomedicine and regenerative medicine are discussed in detail. The authors have focused on 4D printing of various tissues, with a special highlight on bone and dental tissue. Graphical abstract

A drug to be successfully launched in the market requires a significant amount of capital, resources and time, where the unsuccessful results in the last stages lead to catastrophic failure for discovering drugs. This is the very reason which calls for the invention of innovative models that can closely mimic the human in vivo model for producing reliable results. Throughout the innovation line, there has been improvement in the rationale in silico designing but yet there is requirement for in vitro-in vivo correlations. During the evolving of the drug testing models, the 3D models produced by different methods have been proven to produce better results than the traditional 2D models. However, the in vitro fabrications of live tissues are still bottleneck in realizing their complete potential. There is an urgent need for the development of single, standard and simplified in vitro 3D tissue models that can be reliable for investigating the biological and pathological aspects of drug discovery, which is yet to be achieved. The existing pre-clinical models have considerable drawbacks despite being the gold standard in pre-clinical research. The major drawback being the interspecies differences and low reliability on the generated results. This gap could be overcome by the fabrication of bioengineered human disease models for drug screening. The advancement in the fabrication of 3D models will provide a valuable tool in screening drugs at different stages as they are one step closer to bio-mimic human tissues. In this review, we have discussed on the evolution of preclinical studies, and different models, including mini tissues, spheroids, organoids, bioengineered three dimensional models and organs on chips. Furthermore, we provide details of different disease models fabricated across various organs and their applications. In addition to this, the review also focuses on the limitations and the current prospects of the role of three dimensionally bioprinted models in drug screening and development.

Transformative bioprinting, particularly 4D printing, is revolutionizing the field of biofabrication, offering dynamic solutions that respond to external s