Steroids exhibit a range of biological activities and are commonly described as the ‘key to life’ in nature. Steroidal-based medications have emerged as the second largest pharmaceutical category following antibiotics, owing to their remarkable bioactivities such as anti-infective, anti-inflammatory, anti-allergic, and antitumor properties. This category encompasses more than 400 drug compounds, representing approximately 17% of FDA-approved medications. The synthesis of steroidal products continues to attract significant attention due to their diverse bioactivities and physicochemical characteristics in pharmaceutical applications. With the increasing demand for steroidal drugs and the fluctuating availability of sapogenin resources, the use of Mycobacteria to convert inexpensive phytosterols to produce key intermediates for steroid drugs has been established as the most mature and sustainable industrial route. However, the complex structure of steroids, particularly their highly oxygenated skeleton, poses challenges for the well-established semi-synthesis route of complex steroid medications. Recent strides in bioinformatics and genetics have significantly advanced the studies on synthesis of steroidal compounds. This review highlights recent advancements in the synthesis of high-value steroids, including the diverse steroid drug intermediate production via external steroidal modifying enzymes expression in engineered Mycobacteria, chemo-enzymatic synthesis of complex steroids, and yeast-based de novo synthesis. It specifically highlights the significant achievements in the chemo-enzymatic synthesis, which combines the precise site- and stereoselectivity of enzymatic transformations with the efficiency of chemosynthesis, enabling the concise synthesis of complex steroidal products. Recent advancements in chemoenzymatic strategies, especially those involving P450 hydroxylase, 3-sterone-Δ¹-dehydrogenase, reductase, and enzyme cascades, have significantly contributed to the efficient and straightforward synthesis of complex steroid medications. On this basis, the future research opportunities and challenges are also discussed, aiming to provide a reference for the efficient development of more value-added steroid compounds, including the development of new generation steroid intermediates, the discovery of novel steroid biocatalysts, and the establishment of steroid synthesis pathways in mycobacteria.

Advances in science and technology are creating huge benefits and value for society. The digitalization of the world has brought great changes to human being’s daily life. Meanwhile, the increasing degree of digitalization has led to an unprecedented explosion of data, resulting in increasingly severe information storage challenges. According to the current developing trend, the global data volume is expected to reach 175 zettabytes by 2025. With the rapid growth of global data volume and the exponential growth of total data, the existing storage methods will no longer be able to meet the storage needs brought by the digitalization of the world and then there is an urgent need to develop information storage methods with better storage performance, higher storage efficiency and more durable storage media. Nature has offered a powerful solution by using DNA molecules as carriers of information, where genetic information has been transferred stably more than a million years. DNA storage has many advantages over traditional storage media, including high storage density, potentially low maintenance costs, and ease of synthesis and chemical modification, which make it an ideal alternative for information storage. The current process of storing data in DNA includes six main steps: encoding, writing, preservation, retrieval, reading, and decoding. Among them, the writing of data is the basic for realizing the storage of data in DNA, concluding writing data in DNA sequence and in DNA structure. In this review, we first introduce strategies for in vivo data writing in DNA storage systems, which primarily involve writing data into DNA sequences and DNA structures. This is followed by an overview of the development of in vivo writing techniques in DNA storage systems. Finally, we discuss the challenges faced by DNA storage systems in terms of high writing costs and slow writing speeds, and prospects for large-scale synthesis of high-purity DNA and improved biocatalysts.

The extensive consumption of fossil oil and the rapid accumulation of greenhouse gas emissions have caused long-term changes in the global climate and environment, sparking widespread interest in society for CO₂ bioconversion technologies as a means to address energy transition and climate change. As a new-generation biorefinery platform based on synthetic biology, the synthetic phototrophic community comprises closely cooperating phototrophic and heterotrophic microorganisms. This community is capable of efficiently converting light energy directly into biomass and a variety of chemicals through mutualistic metabolic division of labor among community members. Synthetic phototrophic community is one of the potential ways to achieve sustainable carbon-negative biomanufacturing, and has attracted widespread attention attributed to its advantages in applicability and robustness. In recent years, with the rapid development of systems biology and synthetic biotechnology, a variety of research efforts have been applied to the design and optimization of synthetic phototrophic communities, achieving stable progress and promoting the understanding of phototrophic community production. In this review, we briefly introduced an overview of the advances and current status of synthetic phototrophic community, including mutualistic mechanisms related to element, energy, and information flow. Subsequently, the unique advantages of phototrophic community were outlined. Meanwhile, recent systems biology approaches of phototrophic community were summarized, such as integrative analysis of multi-omics data, genome-scale metabolic modelling, flux balance analysis and community performance predictive algorithms. We also focused on the design and optimization strategies, such as chassis upgrading, immobilization/compartmentalization techniques, and enhanced internal multilayer regulation of synthetic phototrophic community, as well as the progress of their applications in various fields. Furthermore, we analyzed and discussed the constraints and challenges for the further deployment of synthetic phototrophic community on a larger scale, ranging from photosynthetic carbon production rate, intermediate organic matter selection, external predator invasion, to light distribution under high density cultivation. Finally, the future research strategies and engineering directions of synthetic phototrophic community encompassing semiconductor biohybrids, fine regulation of interspecies interaction and multi-omics community model construction were proposed. We conclude by providing a perspective on the future application scenarios of synthetic phototrophic communities in biochemistry, biomedicine, bioremediation and bioagriculture.

Organic acids, as important platform chemicals, have been widely used in food, pharmaceutical, chemical industries and agriculture. Currently, microbial production of organic acids relies primarily on sugars as feedstocks, which may suffer from the competition with food and arable lands. One carbon (C₁) molecules such as CO, CO₂, methane, methanol and formic acid are widespread and inexpensive, which are considered as ideal feedstocks for future bio-manufacturing. Bioconversion of C₁ feedstocks toward the production of organic acids helps mitigate greenhouse effect and realize carbon neutrality. Therefore C₁ sources have been regarded as raw materials of third generation biorefinery, and natural C₁ utilizing microbes attracted increasing attention. Although some microorganisms have native biosynthetic pathway of organic acids, the production efficiency is usually lower than expected. This review summarizes the recent progress on the biosynthesis of organic acids (3-hydroxypropionic acid, lactic acid and succinic acid) from C₁ feedstocks using synthetic biology methods. First, the native C₁ utilizing pathways are summarized, including CO₂, CO, methane, methanol and formic acid. Then the metabolic engineering strategies to improve organic acids production were systematically reviewed, including the optimization of rate-limiting enzymes expression, enhancement of the supply of precursor and cofactor, cofactor engineering, and inhibition of the product degradation. In addition, the challenges, solutions, and prospects of C₁ bioconversion to organic acids are also discussed, and coupling chemical catalysis and biological transformation may provide a promising industrial route for organic acids production. In particular, methanol is an ideal C₁ feedstock with many advantages like convenient storage and transportation, high liquid-to-liquid mass transfer efficiency, and it can also be massively produced from CO₂ by “liquid sunshine” technology. Therefore constructing high efficient methanol cell factory may enable organic acids production from CO₂, a carbon neutral production manner. This review may provide a guidance for C₁ biorefinery and industrial bioproduction of organic acids.

Synthetic biology offers boundless possibilities and revolutionary changes to material fields. One remarkable outcome of interdisciplinary integration of synthetic biology and material science is the development of environmentally friendly polyhydroxyalkanoates (PHAs), which serve as ideal alternatives to petroleum-based plastics. PHAs are a family of linear biopolyesters synthesized by various microorganisms as their intracellular storage materials for energy and carbon sources. With at least 150 various monomers, PHAs exhibit diverse structures, material properties, and applications, collectively known as “PHAomics”. When reprograming microbial genomes via synthetic biology and metabolic engineering, in combination with the feeding of special precursors, tailor-made PHAs with defined structures and varied properties can be synthesized. PHAs has been extensively studied in both academia and industry in the last few decades, leading to the commercialization of some PHAs. Next generation industrial biotechnology (NGIB) based on halophilic Halomonas spp. as chassis has been developed to overcome the limitations of current industrial biotechnology. NGIB offers a long lasting, open and continuous, energy and freshwater-saving bioprocess using low-cost mixed substrates and allows morphology engineering for simplified downstream processing. NGIB facilitates low-cost production of various PHAs in large scale. This review introduces PHAomics and summarizes the diverse properties of PHAs produced via NGIB. It primarily focuses on the composition, structure, and material properties of PHAs, as well as their extensive applications in biodegradable plastics, medical implants, medicine, drug delivery carriers, energy sources, and potential smart materials. Additionally, it covers the strategies and tools for strain engineering and their achievements in the tailor-made biosynthesis of PHA using reprogrammed Pseudomonas spp. and Halomonas spp. Finally, this review discusses strategies on how to further reduce the production cost and improve material properties of PHAs. This review summarizes the progresses on the low-cost customized synthesis of PHA biomaterials by synthetic biology, demonstrating the integration of biology and chemistry.

Glycosylation modifications, extensively present on the surfaces of eukaryotic proteins as a type of post-translational modification, hold significant physiological and pathological implications. The microscopic heterogeneity of natural glycoproteins has led to the emergence of the chemical synthesis of homogeneous glycoproteins with defined structures as a crucial frontier in exploring the structure-function relationships of glycosylation modifications. With the flourishing development of protein synthesis and glycoengineering technologies, various protein ligation and polysaccharide synthesis strategies have been developed, enabling the preparation of glycoproteins containing hundreds of amino acid residues. The development of glycoprotein synthesis strategies primarily revolves around chemical and enzymatic approaches for glycosidic bond formation, leading to effective synthesis schemes such as Lansbury’s aspartic acid acylation, chemical strategies based on glycosyl amino acid building blocks, and glycan remodeling strategies using endoglycosidases and glycosyltransferases. This review will discuss the chemical and enzymatic construction of glycosidic bonds, examining existing strategies for the total synthesis of glycoproteins and semi-synthetic approaches that combine with biological expression methods. It will introduce these strategies’ achievements in synthesizing complex homogeneous glycoproteins with different types of glycosylation modifications, such as those with multiple complex N-glycosylation modifications like HSV gD and those containing long hydrophobic segments like IL-2. Additionally, this review will highlight breakthroughs in understanding the structure-function relationships of glycosylation modifications in various physiological processes through these synthetic complex glycoproteins, including the relationship between glycan chain length and immunogenicity in antigenic glycoproteins, and the mechanisms by which O-GlcNAc regulates synaptic function in neurons. Finally, it will summarize the progress made in glycosidic bond construction, purification strategies, and protein solubility, and point out that further optimization of selectivity and synthetic yield remains a pressing issue in the field of glycoprotein synthesis. The wide application of glycoprotein synthesis technology in developing immunotherapies and understanding the molecular mechanisms of various diseases expands the development directions of synthetic science in the field of life and health, from understanding principles to developing products.

In order to achieve carbon neutrality and green economy, people use biorefinery technology to transform and utilize CO₂. Microbial electrosynthesis (MES) is an emerging technology that converts CO₂ into chemicals by electrically driven biocatalysts. Currently, the low efficiency of microbial carbon sequestration, an incomplete understanding of electron transfer mechanisms, low synthesis rate, and poor applicability of reactor components have been the limiting factors for the large-scale application of MES. In this paper, the mechanisms of electron supply in the MES system, including through electrodes and electron donors such as H₂, formic acid, CO, and other molecules, are systematically reviewed based on how cathodic microorganisms obtain electrons. It is an effective method to improve electron transport efficiency by modifying conductive nanowires of electroactive microorganisms and optimizing the expression of microbially associated hydrogenase, formate dehydrogenase and CO dehydrogenase using synthetic biology techniques. Additionally, cathode modification aimed at improving electron transfer rates between microbes and electrodes, enhancing the biocompatibility, and providing more reducing power can facilitate the generation of value-added products. In addition to enhancing the electron transfer efficiency of the cathode, the construction of a reactor with high efficiency of gas-liquid-solid mass transfer and electron transfer, the reduction of anode potential for water electrolysis, and the regulation of microbial activity are also important strategies to enhance MES performance. In the future, it is necessary to further elucidate the mechanism of microbial electron transport and strengthen the performance of MES by means of synthetic biological communities, and by designing a more efficient electrode interface that balances electron transfer rate, substrate mass transfer and biocompatibility. In terms of the scaling-up of reaction devices, electron transfer and gas mass transfer can be improved through the combination of various methods, and integrating product separation processes can promote the further development of the technology and provide new ideas for the realization of the “Carbon Peak and Carbon Neutrality” goal.

Photocatalysis has the advantages of mild reaction conditions, renewability, and strong reactivity, but the poor selectivity limits its further application in asymmetric synthesis. Enzymatic catalysis shows unique advantages of high selectivity and specificity, but it leads to some defects such as limited reaction types and relatively narrow substrate scope. Photoenzymatic catalysis combines the advantages of high reactivity of photocatalysis with high selectivity of enzymatic catalysis, providing a novel synthesis model, that is more in line with the requirements of modern green organic synthesis. The term “photoenzyme reactions” narrowly refers to the synergistic catalysis involving photoenzymes, which can be classified into the following four categories: natural photoenzymactic reactions, artificial photoenzymatic reactions, photo-biocatalysis cascade reactions, and photo-induced promiscuous enzymatic reactions. However, natural photoenzymes are rarely found in nature, the stringent substrate scope further hinders their application. Artificial photoenzymes integrate photosensitizers into the scaffold of natural enzymes, which have been well summarized in previous reviews. Photo-biocatalysis cascade reactions by combining photochemical steps and enzymatic steps can realize some complex organic synthesis processes. Since the first report on NAD(P)H-dependent KREDs-catalyzed enantioselective radical dehalogenation of lactones, photosensitive cofactor-dependent unnatural photoenzymatic catalysis demonstrated its great potential in the field of organic synthesis, and continues to thrive to date, which has addressed many problems difficult to be achieved in traditional organic synthesis. Since 2023, research into the promiscuity of photoenzyme catalysis has witnessed continuous breakthroughs, reporting diverse novel types of photoenzyme catalytic reactions and mechanisms. The precise control over stereoselectivity and even regioselectivity directly addresses the longstanding challenges in the field of organic synthesis. While there have been many publications summarizing the related research, yet rarely focused on this rapidly evolving field. In this review, we summarize the recent and representative reports of photo-induced promiscuous enzymatic reactions, and classify them according to asymmetric dehalogenation, hydrogenation, intramolecular cyclization, intermolecular C—C/C—N/C—S cross-coupling reactions through free radical pathways, etc. These reactions exhibit different mechanisms due to different enzymes and substrates. For example, in the process of redox initiation, there are two types: single-electron reduction initiation and single-electron oxidation initiation. In the radical termination process, single-electron reduction termination and single-electron oxidation termination may be used. The diversity of mechanisms also makes it possible to develop more photoenzyme-catalyzed promiscuous reactions. In the future, new photoenzymatic methods will be promoted by rapidly developing technologies such as genetic engineering, synthetic biology, enzyme engineering, flow chemistry, and artificial intelligence, and more efficient and highly selective new-to-nature reactions will emerge, significantly expanding the application range of photoenzyme catalysis in the field of green asymmetric synthesis.

Organoid technology, which leverages the cultivation of three-dimensional (3D) miniature organ models from stem cells in vitro to simulate the structure and function of human organs, has emerged as a cornerstone in biomedical fields such as disease modeling and drug screening. Despite its significant contributions, the rapid advancement of this frontier technology also raises profound ethical challenges, necessitating a robust framework for its normalization and legalization. This paper firstly provides a comprehensive analysis of the development of organoid technology, elucidating its distinctive characteristics and substantial value in biomedical applications. Currently, the technology is advancing towards the construction of more complex organ systems, achieving higher fidelity, and integrating more intricately with other cutting-edge technologies. This evolution enhances the capability of organoids to mimic human physiology accurately, thereby improving the predictive accuracy of medical research and pharmaceutical developments. The paper examines the primary ethical challenges raised by organoid technology, including the informed consent of donors, privacy protection, and equitable access to this technology. These issues are pivotal in maintaining public trust and compliance with ethical norms. Additionally, it explores the ethical implications of modeling sensitive organs such as the brain and embryos, raising questions about the moral status of such models and potential psychological impacts on society. It also reviews how various countries and international organizations respond to these ethical controversies. Major developed countries and international bodies have adopted a variety of governance measures, primarily in the form of ethical guidelines or standards, which provide a flexible yet sometimes insufficient framework for addressing rapidly evolving technologies. In contrast, China lacks specific legislative policies regarding organoid technology, indicating a need for tailored governance strategies that align with both international standards and local ethical considerations. In order to bridge these gaps, this paper attempts to construct a “moral assessment scale” framework. This tool is designed to quantify ethical considerations and guide decision-making in organoid research and application. The paper advocates for strengthened interdisciplinary cooperation and the improvement of the informed consent process, essential for ethical compliance. Moreover, establishing an international unified ethical code could facilitate global cooperation and harmonize standards across borders. Supporting ethical research and fostering public discussions are also crucial for the responsible development of organoid technologies. By thoroughly examining the ethical challenges and proposing actionable solutions, this paper aims to foster a balance between scientific innovation and ethical responsibility. This balanced approach will not only advance the field but also ensure that it develops in a manner respecting human dignity and societal values, ultimately better serving human health and well-being.

Pluripotent stem cells are characterized by self-renewal and multi-differentiation potential, which can be used to reverse structurally dysfunctional tissues and organs back to a structurally and functionally intact state of health through repair, replacement, or in-situ regeneration of new cells, tissues, and even organs. Cells or multicellular systems derived from pluripotent stem cell differentiation, especially organoids, have great potential for application in regenerative medicine. However, the clinical application of stem cell-related therapies is still in its infancy, and the current challenges to the clinical translation of stem cells include the tumorigenicity, heterogeneity, and immunogenicity of stem cell derivatives. Synthetic biology, with its “top-down” design concept and powerful toolkit including synthetic receptors and gene circuits, allows for the rational assembly of standardized modules. With the rapid development of gene editing technology and the deepening of cell biology research, the engineering object of synthetic biology has shifted from lower model organisms such as Escherichia coli or Saccharomyces cerevisiae to mammalian cells. On the one hand, “top-down” design strategies can engineer stem cells by giving them new functions, and on the other hand, the acquisition of new phenotypes by stem cells can test known gene functions and improve understanding of cell biology. Therefore, the application of these synthetic biology tools to stem cell engineering provides new strategies and platforms for relevant cell therapies or organ transplantation. It offers potential advantages in precise control of cell fate, regulation of cell communication, optimization of organoid structure and function, and monitoring and elimination of tumorigenic cells. These synthetic biology tools have provided new strategies and platforms for the engineering and reprogramming of stem cells, offering the potential to address current challenges in the clinical application of stem cells. They are expected to drive further advancements in regenerative medicine and ultimately achieve the core goal of regenerative medicine, which is organ regeneration.