Cytoprotective Encapsulation of Individual Jurkat T Cells within Durable TiO2 Shells for T-Cell Therapy

Ultrafast, cytocompatible mineralization of calcium phosphate in the formation of stratified nanoshells of artificial spores

Spatially controlled confinement of catalytic enzymes within nanoshells holds substantial potential for applications in bioreactors, synthetic cells, and artificial spores. The utilization of amorphous calcium phosphate (CaP) precursors enables the extremely rapid (<5 seconds) construction of thick (∼400 nm) CaP nanoshells, stratified with distinct enzymes, on various tannic acid-primed substrates. Saccharomyces cerevisiae cells are nanoencapsulated with enzyme-embedded, multilayered CaP nanoshells in a cytocompatible manner, providing an advanced chemical tool for interfacing living cells with functional entities in a spatially controlled configuration.

Engineering live cell surfaces with polyphenol-functionalized nanoarchitectures

Cell surface functionalization has emerged as a powerful strategy for modulating cellular behavior and expanding cellular capabilities beyond their intrinsic biological limits. Natural phenolic molecules present as 'green' and versatile building blocks for constructing cell-based biomanufacturing and biotherapeutic platforms. Due to the abundant catechol or galloyl groups, phenolic molecules can dynamically and reversibly bind to versatile substrates via multiple molecular interactions. A range of self-assembled cytoadhesive polyphenol-functionalized nanoarchitectures (cytoPNAs) can be formed via metal coordination or macromolecular self-assembly that can rapidly attach to cell surfaces in a cell-agnostic manner. Additionally, the cytoPNAs attached on the cell surface can also provide active sites for the conjunction of bioactive payloads, further expanding the structural repertoire and properties of engineered cells. This Perspective introduces the wide potential of cytoPNA-mediated cell engineering in three key applications: (1) creating inorganic-organic biohybrids as cell factories for efficient production of high-value chemicals, (2) constructing engineered cells for cell-based therapies with enhanced targeting specificity and nano-bio interactions, and (3) encapsulating microbes as biotherapeutics for the treatment of gastrointestinal tract-related diseases. Collectively, the rapid, versatile, and modular nature of cytoPNAs presents a promising platform for next-generation cell engineering and beyond.

Natural biomolecules for cell-interface engineering

Cell-interface engineering is a way to functionalize cells through direct or indirect self-assembly of functional materials around the cells, showing an enhancement to cell functions. Among the materials used in cell-interface engineering, natural biomolecules play pivotal roles in the study of biological interfaces, given that they have good advantages such as biocompatibility and rich functional groups. In this review, we summarize and overview the development of studies of natural biomolecules that have been used in cell-biointerface engineering and then review the five main types of biomolecules used in constructing biointerfaces, namely DNA polymers, amino acids, polyphenols, proteins and polysaccharides, to show their applications in green energy, biocatalysis, cell therapy and environmental protection and remediation. Lastly, the current prospects and challenges in this area are presented with potential solutions to solve these problems, which in turn benefits the design of next-generation cell engineering.

Construction of Liposome-Based Extracellular Artificial Organelles on Individual Living Cells

Integration of living cells with extrinsic functional entities gives rise to bioaugmented nanobiohybrids, which hold tremendous potential across diverse fields such as cell therapy, biocatalysis, and cell robotics. This study presents a biocompatible method for incorporating multilayered functional liposomes onto the cell surface, creating extracellular artificial organelles or exorganelles. The introduction of various extrinsic functionalities to cells is achieved without comprising their viabilities. The integration of extrinsic enzymatic reactions is exemplified through the cascade reaction involving glucose oxidase and horseradish peroxidase. Furthermore, our protocol offers the design flexibility to customize liposome compositions, thereby providing effective cell modification. The versatility of the liposome-based exorganelle approach establishes an advanced chemical tool, empowering cells with novel functionalities that surpass or are complementary to their innate capabilities.

Polyphenol-Nanoengineered Monocyte Biohybrids for Targeted Cardiac Repair and Immunomodulation

Myocardial infarction is one of the leading cause of cardiovascular death worldwide. Invasive interventional procedures and medications are applied to attenuate the attacks associated with ischemic heart disease by reestablishing blood flow and restoring oxygen supply. However, the overactivation of inflammatory responses and unsatisfactory drug delivery efficiency in the infarcted regions prohibit functional improvement. Here, a nanoengineered monocyte (MO)-based biohybrid system, referred to as CTAs @MOs, for the heart-targeted delivery of combinational therapeutic agents (CTAs) containing anti-inflammatory IL-10 and cardiomyogenic miR-19a to overcome the limitation of malperfusion within the infarcted myocardium through a polyphenol-mediated interfacial assembly, is reported. Systemic administration of CTAs@MOs bypasses extensive thoracotomy and intramyocardial administration risks, leading to infarcted heart-specific accumulation and sustained release of therapeutic agents, enabling immunomodulation of the proinflammatory microenvironment and promoting cardiomyocyte proliferation in sequence. Moreover, CTAs@MOs, which serve as a cellular biohybrid-based therapy, significantly improve cardiac function as evidenced by enhanced ejection fractions, increased fractional shortening, and diminished infarct sizes. This polyphenol nanoengineered biohybrid system represents a general and potent platform for the efficient treatment of cardiovascular disorders.

Temporary Nanoencapsulation of Human Intestinal Organoids Using Silk Ionomers

Human intestinal organoids (HIOs) are vital for modeling intestinal development, disease, and therapeutic tissue regeneration. However, their susceptibility to stress, immunological attack, and environmental fluctuations limits their utility in research and therapeutic applications. This study evaluated the effectiveness of temporary silk protein-based layer-by-layer (LbL) nanoencapsulation technique to enhance the viability and functions of HIOs against common biomedical stressors, without compromising their native functions. Cell viability and differentiation capacity are assessed, finding that nanoencapsulation significantly improved HIO survival under the various environmental perturbations studied without compromising cellular functionality. Post-stress exposures, the encapsulated HIOs still successfully differentiated into essential intestinal cell types such as enterocytes, goblet cells, enteroendocrine cells, and Paneth cells. Moreover, the silk nanocoatings effectively protected against environmental stressors such as ultraviolet (UV) light exposure, protease degradation, antibody binding, and cytokine-induced inflammation. This nanoencapsulation technique shows promise for advancing HIO applications in disease modeling, drug testing, and potential transplantation therapies.

Directing the Encapsulation of Single Cells with DNA Framework Nucleator-Based Hydrogel Growth

Encapsulating individual mammalian cells with biomimetic materials holds potential in ex vivo cell culture and engineering. However, current methodologies often present tradeoffs between homogeneity, stability, and cell compatibility. Here, inspired by bacteria that use proteins stably anchored on their outer membranes to nucleate biofilm growth, we develop a single-cell encapsulation strategy by using a DNA framework structure as a nucleator (DFN) to initiate the growth of DNA hydrogels under cell-friendly conditions. We find that among the tested structures, the tetrahedral DFN can evenly and stably reside on cell membranes, effectively initiating hybridization chain reactions which generate homogeneously dense yet flexible single-cell encapsulation for diverse cell lines. The encapsulation persists for up to 72 hours in a serum-containing cell culture environment, representing a ~70-fold improvement compared to encapsulations mediated by single-stranded DNA nucleators. The metabolism and proliferation of the encapsulated cells are suppressed, but can be restored to the original efficiencies upon release, suggesting the superior cell compatibility of the encapsulation. We also find that compared to naked cells, the encapsulated cells exhibit a lower autophagy level after undergoing mechanical stress, suggesting the protective effect of the DNA encapsulation. This method may provide a new tool for ex vivo cell engineering.

Organismal Function Enhancement through Biomaterial Intervention

Living organisms in nature, such as magnetotactic bacteria and eggs, generate various organic-inorganic hybrid materials, providing unique functionalities. Inspired by such natural hybrid materials, researchers can reasonably integrate biomaterials with living organisms either internally or externally to enhance their inherent capabilities and generate new functionalities. Currently, the approaches to enhancing organismal function through biomaterial intervention have undergone rapid development, progressing from the cellular level to the subcellular or multicellular level. In this review, we will concentrate on three key strategies related to biomaterial-guided bioenhancement, including biointerface engineering, artificial organelles, and 3D multicellular immune niches. For biointerface engineering, excess of amino acid residues on the surfaces of cells or viruses enables the assembly of materials to form versatile artificial shells, facilitating vaccine engineering and biological camouflage. Artificial organelles refer to artificial subcellular reactors made of biomaterials that persist in the cytoplasm, which imparts cells with on-demand regulatory ability. Moreover, macroscale biomaterials with spatiotemporal regulation characters enable the local recruitment and aggregation of cells, denoting multicellular niche to enhance crosstalk between cells and antigens. Collectively, harnessing the programmable chemical and biological attributes of biomaterials for organismal function enhancement shows significant potential in forthcoming biomedical applications.

A Micrometric Transformer: Compositional Nanoshell Transformation of Fe3+ -Trimesic-Acid Complex with Concomitant Payload Release in Cell-in-Catalytic-Shell Nanobiohybrids

Nanoencapsulation of living cells within artificial shells is a powerful approach for augmenting the inherent capacity of cells and enabling the acquisition of extrinsic functions. However, the current state of the field requires the development of nanoshells that can dynamically sense and adapt to environmental changes by undergoing transformations in form and composition. This paper reports the compositional transformation of an enzyme-embedded nanoshell of Fe3+ -trimesic acid complex to an iron phosphate shell in phosphate-containing media. The cytocompatible transformation allows the nanoshells to release functional molecules without loss of activities and biorecognition, while preserving the initial shell properties, such as cytoprotection. Demonstrations include the lysis and killing of Escherichia coli by lysozyme, and the secretion of interleukin-2 by Jurkat T cells in response to paracrine stimulation by antibodies. This work on micrometric Transformers will benefit the creation of cell-in-shell nanobiohybrids that can interact with their surroundings in active and adaptive ways.

Yolk-Shell Encapsulation of Cells by Biomimetic Mineralization and Visible Light-Induced Surface Graft Polymerization

The pursuit of low-cytotoxicity modification strategies represents a prominent avenue in cell coating research, holding immense significance for the advancement of practical living cell-related technologies. Here, we presented a novel method to fabricate encapsulated yeast cells with a yolk-shell structure by biomimetic mineralization and visible-light-induced surface graft polymerization. In this approach, an amorphous calcium carbonate (ACC) shell was first deposited on the surface of a yeast cell (cell@ACC) modified with 4 layers of self-assembled poly(diallyl dimethylammonium chloride) (PDADMAC)/poly(acrylic acid) (PAA) film using a biomimetic mineralization technique. Subsequently, polyethylenimine (PEI) was absorbed on the surface of cell@ACC by electrostatic interaction. Then, a cross-linked shell was introduced by surface-initiated graft polymerization of poly(ethylene glycol) diacrylate (PEGDA) on cell@ACC under irradiation of visible light using thioxanthone catechol-O,O'-diacetic acid as the photosensitizer. After the removal of the inner ACC shell, the yolk-shell-structured yeast cells (cell@PHS) were obtained. Due to the mild conditions of the strategy, the cell@PHS could retain 98.81% of its original viability. The introduction of the shell layer significantly prolonged the lag phase of yeast cells, which could be tuned between 5 and 25 h by regulating the thickness of the shell. Moreover, the cell@PHS showed improved resistance against lyticase due to the presence of a protective shell. After 30 days of storage, the viability of cell@PHS was 81.09%, which is significantly higher than the 19.89% viability of native yeast cells.

Cell Surface Engineering Tools for Programming Living Assemblies

Breakthroughs in precision cell surface engineering tools are supporting the rapid development of programmable living assemblies with valuable features for tackling complex biological problems. Herein, the authors overview the most recent technological advances in chemically- and biologically-driven toolboxes for engineering mammalian cell surfaces and triggering their assembly into living architectures. A particular focus is given to surface engineering technologies for enabling biomimetic cell-cell social interactions and multicellular cell-sorting events. Further advancements in cell surface modification technologies may expand the currently available bioengineering toolset and unlock a new generation of personalized cell therapeutics with clinically relevant biofunctionalities. The combination of state-of-the-art cell surface modifications with advanced biofabrication technologies is envisioned to contribute toward generating living materials with increasing tissue/organ-mimetic bioactivities and therapeutic potential.

Advancing cell surface modification in mammalian cells with synthetic molecules

Biological cells, being the fundamental entities of life, are widely acknowledged as intricate living machines. The manipulation of cell surfaces has emerged as a progressively significant domain of investigation and advancement in recent times. Particularly, the alteration of cell surfaces using meticulously crafted and thoroughly characterized synthesized molecules has proven to be an efficacious means of introducing innovative functionalities or manipulating cells. Within this realm, a diverse array of elegant and robust strategies have been recently devised, including the bioorthogonal strategy, which enables selective modification. This review offers a comprehensive survey of recent advancements in the modification of mammalian cell surfaces through the use of synthetic molecules. It explores a range of strategies, encompassing chemical covalent modifications, physical alterations, and bioorthogonal approaches. The review concludes by addressing the present challenges and potential future opportunities in this rapidly expanding field.

Polymerization in living organisms

Vital biomacromolecules, such as RNA, DNA, polysaccharides and proteins, are synthesized inside cells via the polymerization of small biomolecules to support and multiply life. The study of polymerization reactions in living organisms is an emerging field in which the high diversity and efficiency of chemistry as well as the flexibility and ingeniousness of physiological environment are incisively and vividly embodied. Efforts have been made to design and develop in situ intra/extracellular polymerization reactions. Many important research areas, including cell surface engineering, biocompatible polymerization, cell behavior regulation, living cell imaging, targeted bacteriostasis and precise tumor therapy, have witnessed the elegant demeanour of polymerization reactions in living organisms. In this review, recent advances in polymerization in living organisms are summarized and presented according to different polymerization methods. The inspiration from biomacromolecule synthesis in nature highlights the feasibility and uniqueness of triggering living polymerization for cell-based biological applications. A series of examples of polymerization reactions in living organisms are discussed, along with their designs, mechanisms of action, and corresponding applications. The current challenges and prospects in this lifeful field are also proposed.

Multishell Colloidosome Platform with Sequential Gastrointestinal Resistance for On-Demand Probiotic Delivery

Probiotic-based oral therapy can potentially prevent and treat diseases by regulating the balance of intestinal flora. However, significant loss of viability and bioactivity of probiotics before reaching the colon results in low delivery efficiency and therapeutic effects, which limits their clinical applications. Here, this work proposes a multishell colloidosome (MSC) platform with sequential gastrointestinal resistance for on-demand probiotic delivery based on biomimetic mineralization and microfluidic technology. Notably, the viability of the decorated probiotics increases 280-fold compared to that of free bacteria during preservation. Because of the sequential gastrointestinal resistance of MSC, encapsulated probiotics exhibit high viability (61%) under continuous exposure to extreme acidity, bile salt erosion, and enzymatic action, whereas free bacteria have a viability of 0%. Moreover, in vitro and in vivo studies reveal that MSC mainly releases probiotics in the colon and improves colonic colonization by probiotics to maintain the integrity of the intestinal barrier and regulate the balance of intestinal flora. Consequently, MSC significantly improves the therapeutic effect on colitis in mice. The MSC platform provides a promising delivery strategy to enhance the efficacy of orally administered probiotics.

Donors for nerve transplantation in craniofacial soft tissue injuries

Neural tissue is an important soft tissue; for instance, craniofacial nerves govern several aspects of human behavior, including the expression of speech, emotion transmission, sensation, and motor function. Therefore, nerve repair to promote functional recovery after craniofacial soft tissue injuries is indispensable. However, the repair and regeneration of craniofacial nerves are challenging due to their intricate anatomical and physiological characteristics. Currently, nerve transplantation is an irreplaceable treatment for segmental nerve defects. With the development of emerging technologies, transplantation donors have become more diverse. The present article reviews the traditional and emerging alternative materials aimed at advancing cutting-edge research on craniofacial nerve repair and facilitating the transition from the laboratory to the clinic. It also provides a reference for donor selection for nerve repair after clinical craniofacial soft tissue injuries. We found that autografts are still widely accepted as the first options for segmental nerve defects. However, allogeneic composite functional units have a strong advantage for nerve transplantation for nerve defects accompanied by several tissue damages or loss. As an alternative to autografts, decellularized tissue has attracted increasing attention because of its low immunogenicity. Nerve conduits have been developed from traditional autologous tissue to composite conduits based on various synthetic materials, with developments in tissue engineering technology. Nerve conduits have great potential to replace traditional donors because their structures are more consistent with the physiological microenvironment and show self-regulation performance with improvements in 3D technology. New materials, such as hydrogels and nanomaterials, have attracted increasing attention in the biomedical field. Their biocompatibility and stimuli-responsiveness have been gradually explored by researchers in the regeneration and regulation of neural networks.

Advances in single-cell nanoencapsulation and applications in diseases

Single-cell nanoencapsulation is a method of coating the surface of single cell with nanomaterials. In the early 20th century, with the introduction of various types of organic or inorganic nano-polymer materials, the selection of cell types, and the functional modification of the outer coating, this technology has gradually matured. Typical preparation methods include interfacial polycondensation, complex condensation, spray drying, microdroplet ejection, and layer-by-layer (LbL) self-assembly. The LbL assembly technology utilises nanomaterials with opposite charges deposited on cells by strong interaction (electrostatic interaction) or weak interaction (hydrogen bonding, hydrophobic interaction), which drives compounds to spontaneously form films with complete structure, stable performance and unique functions on cells. According to the needs of the disease, choosing appropriate cell types and biocompatible and biodegradable nanomaterials could achieve the purpose of promoting cell proliferation, immune isolation, reducing phagocytosis of the reticuloendothelial system, prolonging the circulation time in vivo, and avoiding repeated administration. Therefore, encapsulated cells could be utilised in various biomedical fields, such as cell catalysis, biotherapy, vaccine manufacturing and antitumor therapy. This article reviews cell nanoencapsulation therapies for diseases, including the various cell sources used, nanoencapsulation technology and the latest advances in preclinical and clinical research.

Cell-in-Catalytic-Shell Nanoarchitectonics: Catalytic Empowerment of Individual Living Cells by Single-Cell Nanoencapsulation

Cell-in-shell biohybrid structures, synthesized by encapsulating individual living cells with exogenous materials, have emerged as exciting functional entities for engineered living materials, with emergent properties outside the scope of biochemical modifications. Artificial exoskeletons have, to date, provided physicochemical shelters to the cells inside in the first stage of technological development, and further advances in the field demand catalytically empowered, cellular hybrid systems that augment the biological functions of cells and even introduce completely new functions to the cells. This work describes a facile and generalizable strategy for empowering living cells with extrinsic catalytic capability through nanoencapsulation of living cells with a supramolecular metal-organic complex of Fe³⁺ and benzene-1,3,5-tricarboxylic acid (BTC). A series of enzymes are embedded in situ, without loss of catalytic activity, in the Fe³⁺ -BTC shells, not to mention the superior characteristics of cytocompatible and rapid shell-forming processes. The nanoshell enhances the catalytic efficiency of multienzymatic cascade reactions by confining reaction intermediates to its internal voids and the nanoencapsulated cells acquire exogenous biochemical functions, including enzymatic cleavage of lethal octyl-β-d-glucopyranoside into d-glucose, with autonomous cytoprotection. The system will provide a versatile, nanoarchitectonic tool for interfacing biological cells with functional materials, especially for catalytic bioempowerment of living cells.

Factors influencing stoichiometry and stability of polyoxometalate - peptide complexes

In the pursuit of understanding the factors guiding interactions between polyoxometalates (POMs) and biomolecules, several complexes between Keggin phosphomolybdate and diglycine have been produced at different acidity and salinity conditions, leading to difference in stoichiometry and in crystal structure. Principal factors determining how the POM and dipeptide interact appear to be pH, ionic strength of the medium, and the molar ratio of POM to peptide. An important effect turned out to be even the structure-directing role of the sodium cations coordinating carbonyl functions of the peptide bond. Given the interest in applying POMs in biological systems, these factors are highly relevant to consider. In the view of recent interest in using POMs as nano catalysts in peptide hydrolysis also the potential Keggin POM transformation in phosphate buffered saline medium was investigated leading to insight that nanoparticles of zirconium phosphate (ZrP) can be actual catalysts for breakdown of the peptide bond.

Cell-based biocomposite engineering directed by polymers

Biological cells such as bacterial, fungal, and mammalian cells always exploit sophisticated chemistries and exquisite micro- and nano-structures to execute life activities, providing numerous templates for engineering bioactive and biomorphic materials, devices, and systems. To transform biological cells into functional biocomposites, polymer-directed cell surface engineering and intracellular functionalization have been developed over the past two decades. Polymeric materials can be easily adopted by various cells through polymer grafting or in situ hydrogelation and can successfully bridge cells with other functional materials as interfacial layers, thus achieving the manufacture of advanced biocomposites through bioaugmentation of living cells and transformation of cells into templated materials. This review article summarizes the recent progress in the design and construction of cell-based biocomposites by polymer-directed strategies. Furthermore, the applications of cell-based biocomposites in broad fields such as cell research, biomedicine, and bioenergy are discussed. Last, we provide personal perspectives on challenges and future trends in this interdisciplinary area.

Site-specific recognition of SARS-CoV-2 nsp1 protein with a tailored titanium dioxide nanoparticle - elucidation of the complex structure using NMR data and theoretical calculation

The ongoing world-wide Severe Acute Respiratory Syndrome coronavirus 2 (SARS-CoV-2) pandemic shows the need for new potential sensing and therapeutic means against the CoV viruses. The SARS-CoV-2 nsp1 protein is important, both for replication and pathogenesis, making it an attractive target for intervention. In this study we investigated the interaction of this protein with two types of titania nanoparticles by NMR and discovered that while lactate capped particles essentially did not interact with the protein chain, the aminoalcohol-capped ones showed strong complexation with a distinct part of an ordered α-helix fragment. The structure of the forming complex was elucidated based on NMR data and theoretical calculation. To the best of our knowledge, this is the first time that a tailored titanium oxide nanoparticle was shown to interact specifically with a unique site of the full-length SARS-CoV-2 nsp1 protein, possibly interfering with its functionality.

Nanocell hybrids for green chemistry

Global concerns about reducing or minimizing the costs associated with toxic waste materials have driven the continuing development of green-cell-based biosynthesis methods. Inspired by the hybridization phenomenon of living organisms, recent interest has arisen in nanocell hybrids that possess multiple new functions. They have potential to propel biosynthesis into a new generation of green chemistry. This review article discusses the development of applications for nanocell hybrids in the areas of sustainable energy, clean environment, and green catalysis. Continuing advances in these hybrids will require combining knowledge from the fields of biology, physics, chemistry, material science, and engineering.

Bionic Dormant Body of Timed Wake-Up for Bacteriotherapy in Vivo

The microorganism has become a promising therapeutic tool for many diseases because it is a kind of cell factory that can efficiently synthesize a variety of bioactive substances. However, the metabolic destiny of microorganisms is difficult to predict in vivo. Here, a timing bionic dormant body with programmable destiny is reported, which can predict the metabolic time and location of microorganisms in vivo and can prevent it from being damaged by the complex biological environment in vivo. Taking the complex digestive system as an example, the bionic dormant body exists in the upper digestive tract as a nonmetabolic dormant body after oral administration and will be awakened to synthesize bioactive substances about 2 h after reaching the intestine. Compared with oral microorganisms alone, the bioavailability of the biomimetic dormant body in the intestine is almost 3.5 times higher. The utilization rate of the oral bionic dormant body to synthesize drugs is 2.28 times higher than oral drugs. We demonstrated the significant efficacies of treatment using Parkinson's disease (PD) mice by dormant body capable of timed neurotransmitter production after oral delivery. The timed bionic dormant body with programmable destiny may provide an effective technology to generate advanced microbial therapies for the treatment of various diseases.

Controllable fabrication of alginate/poly-L-ornithine polyelectrolyte complex hydrogel networks as therapeutic drug and cell carriers

Polyelectrolyte complex (PEC) hydrogels are advantageous as therapeutic agent and cell carriers. However, due to the weak nature of physical crosslinking, PEC swelling and cargo burst release are easily initiated. Also, most current cell-laden PEC hydrogels are limited to fibers and microcapsules with unfavorable dimensions and structures for practical implantations. To overcome these drawbacks, alginate (Alg)/poly-L-ornithine (PLO) PEC hydrogels are fabricated into microcapsules, fibers, and bulk scaffolds to explore their feasibility as drug and cell carriers. Stable Alg/PLO microcapsules with controllable shapes are obtained through aqueous electrospraying technique, which avoids osmotic shock and prolongs the release time. Model enzyme and nanosized cargos are successfully encapsulated and continuously released for more than 21 days. Alg/PLO PEC fibers are then prepared to encapsulate brown adipose progenitors (BAPs) and Jurkat T cells. The electrostatic interactions between Alg and PLO are found to facilitate the printability and self-support ability of Alg/PLO bioinks. Alg/PLO PEC fibers and scaffolds support cell proliferation, differentiation, and functionalization. These results demonstrate new options for biocompatible PEC hydrogel preparation and improve the understanding of PEC hydrogels as drug and cell carriers. STATEMENT OF SIGNIFICANCE: In this study, the concept of polyelectrolyte complex hydrogel networks as drug and cell carriers has been demonstrated. Their feasibility to achieve sustained drug release and cell functionality was explored, from microcapsules to fibers to three-dimension printed scaffolds. PEC microcapsules with controllable shapes were obtained. Therapeutic drugs can be encapsulated and continuously release for more than 21 days. Benefiting from the dynamic interactions of physically crosslinked PEC, self-healing fibers were achieved. Besides, the electrostatic interactions between polyelectrolytes were found to facilitate the printability and self-support ability of PEC bioinks. The PEC fibers and scaffolds with controllable structure supported cell proliferation, differentiation, and function. The outcome of current research promotes design of new biocompatible PEC hydrogels and potential drug and cell carriers.

A Versatile Strategy to Coat Individual Cell with Fully/Partially Covered Shell for Preparation of Self-Propelling Living Cells

Coating living cells with a functional shell has been regarded as an effective way to protect them against environmental stress, regulate their biological behaviors, or extend their functionalities. Here, we reported a facile method to prepare fully or partially coated shells on an individual yeast cell surface by visible light-induced graft polymerization. In this strategy, yeast cells that were surface-absorbed with polyethylenimine (PEI) were deposited on the negatively charged glass slide to form a single layer by electrostatic interaction. Then, surface-initiated graft polymerization of poly(ethylene glycol) diacrylate (PEGDA) on yeast cells under visible light irradiation was carried out to generate cross-linked shells on the cells. The process of surface modification had negligible influence on the viability of yeast cells due to the mild reaction condition. Additionally, compared to the native yeast cells, a 17.5 h of delay in division was observed when the graft polymerization was performed under 15 mW/cm² irradiation for 30 min. Introducing artificial shell endowed yeast cells with significant resistance against lyticase, and the protection can be enhanced by increasing the thickness of shell. Moreover, the partially coated yeast cells would be prepared by simply adjusting the reaction condition such as irradiation density and time. By immobilizing urease on the functional patch, the asymmetrically modified yeast cells exhibited self-propelling capability, and the speed of directional movement reached 4 μm/s in the presence of 200 mM urea. This tunable coating individual cell strategy with varying functionality has great potential applications in fields of cell-based drug delivery, cell therapy, biocatalysis, and tissue engineering.

Gelatin Loaded Titanium Dioxide and Silver Oxide Nanoparticles: Implication for Skin Tissue Regeneration

Treatment of burn wounds has many requirements to ensure wound closure with healthy tissue, increased vascularization, guarantee edema resolution, and control bacterial infection. We propose that titanium oxide (TiO₂) nanoparticles (NPs) will be more efficient than silver dioxide (Ag₂O) in the treatment of burn wounds. Herein, gelatin loaded NPs (GLT-NPs) were evaluated for their efficacy to regenerate second-degree burn wound in rabbit skin. TEM results revealed that the average particle sizes were ⁓ 7.5 and 17 nm for Ag₂O and TiO₂ NPs, respectively. The results of the in vivo application of GLT-NPs on burn wound in the rabbit revealed that both Ag₂O and TiO₂ NPs were efficient than the control none treated (CTRL) and GLT group. In terms of the healing rate, the GLT-TiO₂ did not show any significant difference than GLT-Ag₂O (99.57% vs. 99.85%, p = 0.2). Meanwhile, the healing rate was significantly higher in both NPs' treated groups than CTRL (94.16%, p < 0.01) and GLT group (95.07%, p < 0.05). Also, the histological analysis using H&E staining showed re-epithelization, less edema, and enhanced vascularization in both GLT-NPs than CTRL and GLT groups. Furthermore, immunohistochemical analysis of TGF-β1 and α-SMA revealed significantly a higher expression in both GLT-NPs groups than CTRL and GLT groups at weeks 1 and 2 (p < 0.05). Interestingly, TGF-β1 and α-SMA were substantially higher in GLT- TiO₂ than GLT-Ag₂O at weeks 1 and 2 (p < 0.05), but the expression was not significant at week 3. In conclusion, GLT-NPs showed higher regenerative capacity and enhanced the healing quality after burn wound compared to CTRL and GLT. Graphical abstract.

Cryomicroneedles for transdermal cell delivery

Cell therapies for the treatment of skin disorders could benefit from simple, safe and efficient technology for the transdermal delivery of therapeutic cells. Conventional cell delivery by hypodermic-needle injection is associated with poor patient compliance, requires trained personnel, generates waste and has non-negligible risks of injury and infection. Here, we report the design and proof-of-concept application of cryogenic microneedle patches for the transdermal delivery of living cells. The microneedles are fabricated by stepwise cryogenic micromoulding of cryogenic medium with pre-suspended cells, and can be easily inserted into porcine skin and dissolve after deployment of the cells. In mice, cells delivered by the cryomicroneedles retained their viability and proliferative capability. In mice with subcutaneous melanoma tumours, the delivery of ovalbumin-pulsed dendritic cells via the cryomicroneedles elicited higher antigen-specific immune responses and led to slower tumour growth than intravenous and subcutaneous injections of the cells. Biocompatible cryomicroneedles may facilitate minimally invasive cell delivery for a range of cell therapies.

Design and Encapsulation of Immunomodulators onto Gold Nanoparticles in Cancer Immunotherapy

The aim of cancer immunotherapy is to reactivate autoimmune responses to combat cancer cells. To stimulate the immune system, immunomodulators, such as adjuvants, cytokines, vaccines, and checkpoint inhibitors, are extensively designed and studied. Immunomodulators have several drawbacks, such as drug instability, limited half-life, rapid drug clearance, and uncontrolled immune responses when used directly in cancer immunotherapy. Several strategies have been used to overcome these limitations. A simple and effective approach is the loading of immunomodulators onto gold-based nanoparticles (GNPs). As gold is highly biocompatible, GNPs can be administered intravenously, which aids in increasing cancer cell permeability and retention time. Various gold nanoplatforms, including nanospheres, nanoshells, nanorods, nanocages, and nanostars have been effectively used in cancer immunotherapy. Gold nanostars (GNS) are one of the most promising GNP platforms because of their unusual star-shaped geometry, which significantly increases light absorption and provides high photon-to-heat conversion efficiency due to the plasmonic effect. As a result, GNPs are a useful vehicle for delivering antigens and adjuvants that support the immune system in killing tumor cells by facilitating or activating cytotoxic T lymphocytes. This review represents recent progress in encapsulating immunomodulators into GNPs for utility in a cancer immunotherapeutic regimen.

A Decade of Advances in Single-Cell Nanocoating for Mammalian Cells

Strategic advances in the single-cell nanocoating of mammalian cells have noticeably been made during the last decade, and many potential applications have been demonstrated. Various cell-coating strategies have been proposed via adaptation of reported methods in the surface sciences and/or materials identification that ensure the sustainability of labile mammalian cells during chemical manipulation. Here an overview of the methodological development and potential applications to the healthcare sector in the nanocoating of mammalian cells made during the last decade is provided. The materials used for the nanocoating are categorized into polymers, hydrogels, polyphenolic compounds, nanoparticles, and minerals, and the corresponding strategies are described under the given set of materials. It also suggests, as a future direction, the creation of the cytospace system that is hierarchically composed of the physically separated but mutually interacting cellular hybrids.

Coating with flexible DNA network enhanced T-cell activation and tumor killing for adoptive cell therapy

Adoptive cell therapy (ACT) is an emerging powerful cancer immunotherapy, which includes a complex process of genetic modification, stimulation and expansion. During these in vitro or ex vivo manipulation, sensitive cells are inescapability subjected to harmful external stimuli. Although a variety of cytoprotection strategies have been developed, their application on ACT remains challenging. Herein, a DNA network is constructed on cell surface by rolling circle amplification (RCA), and T cell-targeted trivalent tetrahedral DNA nanostructure is used as a rigid scaffold to achieve high-efficient and selective coating for T cells. The cytoprotective DNA network on T-cell surface makes them aggregate over time to form cell clusters, which exhibit more resistance to external stimuli and enhanced activities in human peripheral blood mononuclear cells and liver cancer organoid killing model. Overall, this work provides a novel strategy for in vitro T cell-selective protection, which has a great potential for application in ACT.

Alginate@TiO2 hybrid microcapsules with high in vivo biocompatibility and stability for cell therapy

Designing new materials to encapsulate living therapeutic cells for the treatment of the diseases caused by protein or hormone deficiencies is a great challenge. The desired materials need to be biocompatible towards both entrapped cells and host organisms, have long-term in vivo stability after implantation, allow the diffusion of nutrients and metabolites, and ensure perfect immune-isolation. The current work investigates the in vivo biocompatibility and stability of alginate@TiO₂ hybrid microcapsules and the immune-isolation of entrapped HepG2 cells, to assess their potential for cell therapy. A comparison was made with alginate-silica hybrid microcapsules (ASA). These two hybrid microcapsules are implanted subcutaneously in female Wistar rats. The inflammatory responses of the rats are monitored by the histological examination of the implants and the surrounding tissues, to indicate their in vivo biocompatibility towards the hosts. The in vivo stability of the microcapsules is evaluated by the recovery rate of the intact microcapsules after implantation. The immune-isolation of the entrapped cells is assessed by their morphology, membrane integrity and intracellular enzymatic activity. The results show high viability of the entrapped cells and insignificant inflammation of the hosts, suggesting the excellent biocompatibility of alginate@TiO₂ and ASA microcapsules towards both host organisms and entrapped cells. Compared to the ASA microcapsules, more intact alginate@TiO₂ hybrid microcapsules are recovered 2-day and 2-month post-implantation and more cells remain alive, proving their better in vivo biocompability, stability, and immune-isolation. The present study demonstrates that the alginate@TiO₂ hybrid microcapsule is a highly promising implantation material for cell therapy.

Single-cell yolk-shell nanoencapsulation for long-term viability with size-dependent permeability and molecular recognition

Like nanomaterials, bacteria have been unknowingly used for centuries. They hold significant economic potential for fuel and medicinal compound production. Their full exploitation, however, is impeded by low biological activity and stability in industrial reactors. Though cellular encapsulation addresses these limitations, cell survival is usually compromised due to shell-to-cell contacts and low permeability. Here, we report ordered packing of silica nanocolloids with organized, uniform and tunable nanoporosities for single cyanobacterium nanoencapsulation using protamine as an electrostatic template. A space between the capsule shell and the cell is created by controlled internalization of protamine, resulting in a highly ordered porous shell-void-cell structure formation. These unique yolk-shell nanostructures provide long-term cell viability with superior photosynthetic activities and resistance in harsh environments. In addition, engineering the colloidal packing allows tunable shell-pore diameter for size-dependent permeability and introduction of new functionalities for specific molecular recognition. Our strategy could significantly enhance the activity and stability of cyanobacteria for various nanobiotechnological applications.

Polymerization-Mediated Multifunctionalization of Living Cells for Enhanced Cell-Based Therapy

Surface decoration of living cells by exogenous substances offers a unique tool for understanding and tuning cell behaviors, which plays a critical role in cell-based therapy. Here, a facile yet versatile approach for decorating individual living cells with multimodal coatings is reported. By simply co-depositing with dopamine under a cytocompatible condition, various functional small molecules and polymers can be encoded to form a multifunctional coating on a cell's surface. The accessibility and versatility of this method to decorate diverse cells, including bacteria, fungi, and mammalian cells is demonstrated. With the ability to tune surface functions, ligand co-deposited gut microbiota is prepared as oral therapeutics for targeted treatment of colitis. Given the dual cytoprotective and targeting effects of the coating, decorated cells show more than 30-times higher bioavailability in the gut and fourfold higher accumulation in the inflamed tissue in comparison with those of uncoated bacteria. Multimodal therapeutic cells further validate strikingly increased treatment efficacy over clinical aminosalicylic acid in colitis mice. Decorating with multifunctional coatings proposes a robust platform for developing multimodal cells for enhanced cell-based therapy.

Artificial Bioaugmentation of Biomacromolecules and Living Organisms for Biomedical Applications

The synergistic union of nanomaterials with biomaterials has revolutionized synthetic chemistry, enabling the creation of nanomaterial-based biohybrids with distinct properties for biomedical applications. This class of materials has drawn significant scientific interest from the perspective of functional extension via controllable coupling of synthetic and biomaterial components, resulting in enhancement of the chemical, physical, and biological properties of the obtained biohybrids. In this review, we highlight the forefront materials for the combination with biomacromolecules and living organisms and their advantageous properties as well as recent advances in the rational design and synthesis of artificial biohybrids. We further illustrate the incredible diversity of biomedical applications stemming from artificially bioaugmented characteristics of the nanomaterial-based biohybrids. Eventually, we aim to inspire scientists with the application horizons of the exciting field of synthetic augmented biohybrids.

Improvement of organisms by biomimetic mineralization: A material incorporation strategy for biological modification

Biomineralization, a bio-organism controlled mineral formation process, plays an important role in linking biological organisms and mineral materials in nature. Inspired by biomineralization, biomimetic mineralization is used as a bridge tool to integrate biological organisms and functional materials together, which can be beneficial for the development of diversified functional organism-material hybrids. In this review, recent progresses on the techniques of biomimetic mineralization for organism-material combinations are summarized and discussed. Based upon these techniques, the preparations and applications of virus-, prokaryotes-, and eukaryotes-material hybrids have been presented and they demonstrate the great potentials in the fields of vaccine improvement, cell protection, energy production, environmental and biomedical treatments, etc. We suggest that more researches about functional organism and material combination with more biocompatible techniques should be developed to improve the design and applications of specific organism-material hybrids. These rationally designed organism-material hybrids will shed light on the production of "live materials" with more advanced functions in future. STATEMENT OF SIGNIFICANCE: This review summaries the recent attempts on improving biological organisms by their integrations with functional materials, which can be achieved by biomimetic mineralization as the combination tool. The integrated materials, as the artificial shells or organelles, confer diversified functions on the enclosed organisms. The successful constructions of various virus-, prokaryotes-, and eukaryotes-material hybrids have demonstrated the great potentials of the material incorporation strategy in vaccine development, cancer treatment, biological photosynthesis and environment protection etc. The suggested challenges and perspectives indicate more inspirations for the future development of organism-material hybrids.

Self-Assembly of Asymmetrically Functionalized Titania Nanoparticles into Nanoshells

Titania (anatase) nanoparticles were anisotropically functionalized in water-toluene Pickering emulsions to self-assemble into nanoshells with diameters from 500 nm to 3 μm as candidates for encapsulation of drugs and other compounds. The water-phase contained a hydrophilic ligand, glucose-6-phosphate, while the toluene-phase contained a hydrophobic ligand, n-dodecylphosphonic acid. The addition of a dilute sodium alginate suspension that provided electrostatic charge was essential for the self-limited assembly of the nanoshells. The self-assembled spheres were characterized by scanning electron microscopy, elemental mapping, and atomic force microscopy. Drug release studies using tetracycline suggest a rapid release dominated by surface desorption.

Bioinspired cell-in-shell systems in biomedical engineering and beyond: Comparative overview and prospects

With the development in tissue engineering, cell transplantation, and genetic technologies, living cells have become an important therapeutic tool in clinical medical care. For various cell-based technologies including cell therapy and cell-based sensors in addition to fundamental studies on single-cell biology, the cytoprotection of individual living cells is a prerequisite to extend cell storage life or deliver cells from one place to another, resisting various external stresses. Nature has evolved a biological defense mechanism to preserve their species under unfavorable conditions by forming a hard and protective armor. Particularly, plant seeds covered with seed coat turn into a dormant state against stressful environments, due to mechanical and water/gas constraints imposed by hard seed coat. However, when the environmental conditions become hospitable to seeds, seed coat is ruptured, initiating seed germination. This seed dormancy and germination mechanism has inspired various approaches that artificially induce cell sporulation via chemically encapsulating individual living cells within a thin but tough shell forming a 3D "cell-in-shell" structure. Herein, the recent advance of cell encapsulation strategies along with the potential advantages of the 3D "cell-in-shell" system is reviewed. Diverse coating materials including polymeric shells and hybrid shells on different types of cells ranging from microbes to mammalian cells will be discussed in terms of enhanced cytoprotective ability, control of division, chemical functionalization, and on-demand shell degradation. Finally, current and potential applications of "cell-in-shell" systems for cell-based technologies with remaining challenges will be explored.

A Removable Artificial Cell Wall for Withstanding Ciprofloxacin

The pollution of antibiotics in aquaculture environment is increasingly serious, and excessive antibiotics will kill the probiotics in aquaculture feed. How to improve the viability of probiotics in the antibiotics-contaminated environment is of significance. In this study, a new strategy for protecting Saccharomyces cerevisiae cells in situ against antibiotics is constructed based on cell surface engineering technology by putting on wearable protective layers for cells. The protective layer is constructed around cellular surface via the self-assembly of coacervate microdroplets that consist of carboxymethyl chitosan and carboxyl dextran. Without affecting the cell viability, the protective layer can grasp ciprofloxacin and decrease the contact of ciprofloxacin to cells and consequently improve the survival rate of cells when exposing to ciprofloxacin. This work highlights a facile strategy to establish removable artificial cell wall by biodegradable polysaccharides for improving the productivity of probiotics in antibiotic environments.

Single-Cell Nanoencapsulation: From Passive to Active Shells

Single-cell nanoencapsulation is an emerging field in cell-surface engineering, emphasizing the protection of living cells against external harmful stresses in vitro and in vivo. Inspired by the cryptobiotic state found in nature, cell-in-shell structures are formed, which are called artificial spores and which show suppression or retardation in cell growth and division and enhanced cell survival under harsh conditions. The property requirements of the shells suggested for realization of artificial spores, such as durability, permselectivity, degradability, and functionalizability, are demonstrated with various cytocompatible materials and processes. The first-generation shells in single-cell nanoencapsulation are passive in the operation mode, and do not biochemically regulate the cellular metabolism or activities. Recent advances indicate that the field has shifted further toward the formation of active shells. Such shells are intimately involved in the regulation and manipulation of biological processes. Not only endowing the cells with new properties that they do not possess in their native forms, active shells also regulate cellular metabolism and/or rewire biological pathways. Recent developments in shell formation for microbial and mammalian cells are discussed and an outlook on the field is given.

Enzymatically degradable, starch-based layer-by-layer films: application to cytocompatible single-cell nanoencapsulation

The build-up and degradation of cytocompatible nanofilms in a controlled fashion have great potential in biomedical and nanomedicinal fields, including single-cell nanoencapsulation (SCNE). Herein, we report the fabrication of biodegradable films of cationic starch (c-ST) and anionic alginate (ALG) by electrostatically driven layer-by-layer (LbL) assembly technology and its application to the SCNE. The [c-ST/ALG] multilayer nanofilms, assembled either on individual Saccharomyces cerevisiae or on the 2D flat gold surface, degrade on demand, in a cytocompatible fashion, via treatment with α-amylase. Their degradation profiles are investigated, while systematically changing the α-amylase concentration, by several surface characterization techniques, including quartz crystal microbalance with dissipation monitoring (QCM-D) and ellipsometry. DNA incorporation in the LbL nanofilms and its controlled release, upon exposure of the nanofilms to an aqueous α-amylase solution, are demonstrated. The highly cytocompatible nature of the film-forming and -degrading conditions is assessed in the c-ST/ALG-shell formation and degradation of S. cerevisiae. We envisage that the cytocompatible, enzymatic degradation of c-ST-based nanofilms paves the way for developing advanced biomedical devices with programmed dissolution in vivo.

Ca2+-Mediated Surface Polydopamine Engineering to Program Dendritic Cell Maturation

Engineering of cell surfaces holds promise in manipulating cellular activities in a physicochemical route as a complement to the biological approach. Mediated by Ca²⁺, a quick and convenient yet cytocompatible method is used to achieve surface engineering, by which polydopamine nanostructures can be in situ grown onto dendritic cell (DC) surfaces within 10 min. Ca²⁺, as the physical bridge between the negative cell surface and polydopamine, avoids the direct chemical polymerization of polydopamine onto the cell surface, critically important to maintain the cell viability. As a proof of concept in potential applications, this cell surface engineering shows a good control toward DC maturation. Upon surface polydopamine engineering, bone-marrow-derived DC exhibits a unique bidirectional control of maturation. The polydopamine structure enables effective suppression of DC activation by acting as an efficient scavenger of reactive oxygen species, a key signal during maturation. Conversely, an 808 nm laser irradiation can remotely relieve the suppressed state and effectively activate DC maturation by the photoheat effect of polydopamine (39 °C). The work provides an easily implemented, straightforward approach to achieve cell surface engineering, through which the DC maturation can be controlled.

Remodeling of Cellular Surfaces via Fast Disulfide-Thiol Exchange To Regulate Cell Behaviors

Remodeling of cellular surfaces is shown highly effective in the manipulation and control of cell behaviors via nonbiological means. By 5-thio-2-nitrobenzoate-mediated, fast, and reversible disulfide-thiol exchange, a sequential layer by layer assembly process was developed to grow albumin protein shells on cellular surfaces fixed by a disulfide-linked network, in a cytocompatible manner. The artificial shells, accomplished by a double-assembly process, were sustainable up to >1 day, and thereafter gradually bioabsorbed with unaffected cell viability. The surface engineering process enabled dynamic remodeling of cellular surfaces that effectively controlled cell behaviors including regulated cell proliferation, enhanced uptake efficiency of dextran-fluorescein isothiocyanate that is known for cell-impermeability, and targeted imaging. This unique approach was well-validated on tumor cells (B16), immune cells (DC2.4), and neutrophils, showing its potential universality for most of the cells that are rich in thiols. The new strategy will show promise in cell manipulation and targeted imaging.

Click Reaction for Reversible Encapsulation of Single Yeast Cells

Cell surface engineering is an emerging technology to encapsulate cells in order to enhance their functions. However, methods for reversible encapsulation of cells with abiotic functionalities are rare. Herein, we describe a phenylboronic acid based click reaction for encapsulation of single yeast cells using mesoporous silica nanoparticles (MSNs). This encapsulation does not impact natural growth of the cells and leads to a significant enhancement of cell survival in a variety of hostile environments. Owing to the glucose-responsiveness of the boronate ester bond between cell surface polysaccharides and B(OH)2-grafted MSNs, encapsulation was reversible by addition or removal of glucose. This effort offers living cells effective protection under harsh conditions and enables reversible assembling-detaching of abiotic functions.