Near-Infrared-Induced Contractile Proteinosome Microreactor with a Fast Control on Enzymatic Reactions

Quantitative Microscale Thermometry in Droplets Loaded with Gold Nanoparticles

Gold nanoparticles (AuNPs) are increasingly used for their thermoplasmonic properties, i.e., their ability to convert light energy into heat through plasmon resonance. However, measuring temperature gradients generated at the microscale by assemblies of AuNPs remains challenging, especially for random 3D distributions of AuNPs. Here, we introduce a label-free thermometry approach, combining quantitative wavefront microscopy and numerical simulations, to infer the heating power dissipated by a 3D model system consisting of emulsion microdroplets loaded with AuNPs. This approach gives access to the temperature reached in the droplets under laser irradiation without the need for extrinsic calibration. This versatile thermometry method is promising for noninvasive temperature measurements in various 3D microsystems involving AuNPs as colloidal heat sources, including photothermal drug delivery systems.

Bioinspired photocatalytic systems towards compartmentalized artificial photosynthesis

Artificial photosynthesis aims to produce fuels and chemicals from simple building blocks (i.e. water and carbon dioxide) using sunlight as energy source. Achieving effective photocatalytic systems necessitates a comprehensive understanding of the underlying mechanisms and factors that control the reactivity. This review underscores the growing interest in utilizing bioinspired artificial vesicles to develop compartmentalized photocatalytic systems. Herein, we summarize different scaffolds employed to develop artificial vesicles, and discuss recent examples where such systems are used to study pivotal processes of artificial photosynthesis, including light harvesting, charge transfer, and fuel production. These systems offer valuable lessons regarding the appropriate choice of membrane scaffolds, reaction partners and spatial arrangement to enhance photocatalytic activity, selectivity and efficiency. These studies highlight the pivotal role of the membrane to increase the stability of the immobilized reaction partners, generate a suitable local environment, and force proximity between electron donor and acceptor molecules (or catalysts and photosensitizers) to increase electron transfer rates. Overall, these findings pave the way for further development of bioinspired photocatalytic systems for compartmentalized artificial photosynthesis.

Preparation and biomedical applications of artificial cells

Artificial cells have received much attention in recent years as cell mimics with typical biological functions that can be adapted for therapeutic and diagnostic applications, as well as having an unlimited supply. Although remarkable progress has been made to construct complex multifunctional artificial cells, there are still significant differences between artificial cells and natural cells. It is therefore important to understand the techniques and challenges for the fabrication of artificial cells and their applications for further technological advancement. The key concepts of top-down and bottom-up methods for preparing artificial cells are summarized, and the advantages and disadvantages of the bottom-up methods are compared and critically discussed in this review. Potential applications of artificial cells as drug carriers (microcapsules), as signaling regulators for coordinating cellular communication and as bioreactors for biomolecule fabrication, are further discussed. The challenges and future trends for the development of artificial cells simulating the real activities of natural cells are finally described.

Biotic communities inspired proteinosome-based aggregation for enhancing utilization rate of enzyme

Compared with the individuals, the collective behavior of biotic communities could show certain superior characteristics. Inspired by this idea and based on the conjugation between phenylboronic acid-grafted mesoporous silica nanoparticles and the polysaccharide functionalized membrane of proteinosomes, a type of proteinosomes-based aggregations was constructed. We demonstrated the emergent characteristics of proteinosomes aggregations including accelerated settling velocity and population surviving by sacrificing outside members for the inside. Moreover, this kind of "hand in hand" architecture provided the proteinosomes aggregations with the characteristic of resistance to the negative pressure phagocytosis of micropipette, as well as enhancing utilization rate of the encapsulated enzymes. Overall, it is anticipated that the construction and application of proteinosomes aggregations could contribute to advance the functionality of life-like assembled biomaterial in another way.

Biocatalytic Synthesis Using Self-Assembled Polymeric Nano- and Microreactors

Biocatalysis is increasingly being explored for the sustainable development of green industry. Though enzymes show great industrial potential with their high efficiency, specificity, and selectivity, they suffer from poor usability and stability under abiological conditions. To solve these problems, researchers have fabricated nano- and micro-sized biocatalytic reactors based on the self-assembly of various polymers, leading to highly stable, functional, and reusable biocatalytic systems. This Review highlights recent progress in self-assembled polymeric nano- and microreactors for biocatalytic synthesis, including polymersomes, reverse micelles, polymer emulsions, Pickering emulsions, and static emulsions. We categorize these reactors into monophasic and biphasic systems and discuss their structural characteristics and latest successes with representative examples. We also consider the challenges and potential solutions associated with the future development of this field.

Current Strategies for Real-Time Enzyme Activation

Enzyme activation is a powerful means of achieving biotransformation function, aiming to intensify the reaction processes with a higher yield of product in a short time, and can be exploited for diverse applications. However, conventional activation strategies such as genetic engineering and chemical modification are generally irreversible for enzyme activity, and they also have many limitations, including complex processes and unpredictable results. Recently, near-infrared (NIR), alternating magnetic field (AMF), microwave and ultrasound irradiation, as real-time and precise activation strategies for enzyme analysis, can address many limitations due to their deep penetrability, sustainability, low invasiveness, and sustainability and have been applied in many fields, such as biomedical and industrial applications and chemical synthesis. These spatiotemporal and controllable activation strategies can transfer light, electromagnetic, or ultrasound energy to enzymes, leading to favorable conformational changes and improving the thermal stability, stereoselectivity, and kinetics of enzymes. Furthermore, the different mechanisms of activation strategies have determined the type of applicable enzymes and manipulated protocol designs that either immobilize enzymes on nanomaterials responsive to light or magnetic fields or directly influence enzymatic properties. To employ these effects to finely and efficiently activate enzyme activity, the physicochemical features of nanomaterials and parameters, including the frequency and intensity of activation methods, must be optimized. Therefore, this review offers a comprehensive overview related to emerging technologies for achieving real-time enzyme activation and summarizes their characteristics and advanced applications.

Stimuli-Responsive Regulation of Biocatalysis through Metallic Nanoparticle Interaction

The remote control of biocatalytic processes in an extracellular medium is an exciting idea to deliver innovative solutions in the biocatalysis field. With this purpose, metallic nanoparticles (NPs) are great candidates, as their inherent thermal, electric, magnetic, and plasmonic properties can readily be manipulated upon external stimuli. Exploring the unique NP properties beyond an anchoring platform for enzymes brings up the opportunity to extend the efficiency of biocatalysts and modulate their activity through triggered events. In this review, we discuss a set of external stimuli, such as light, electricity, magnetism, and temperature, as tools for the regulation of nanobiocatalysis, including the challenges and perspectives regarding their use. In addition, we elaborate on the use of combined stimuli that create a more refined framework in terms of a multiresponsive system. Finally, we envision this review might instigate researchers in this field of study with a set of promising opportunities in the near future.

Carboxy-Functionalized pH Responsive Capsule Polymer Particles Fabricated by Particulate Interfacial Photocrosslinking

pH-responsive capsule particles show promise for various applications, such as self-healing materials, micro/nanoreactors, and drug delivery systems. Herein, carboxy-functionalized capsule polymer particles possessing neutral-alkali pH responsive controlled release capability were...

Biocatalytic self-assembled synthetic vesicles and coacervates: From single compartment to artificial cells

Compartmentalization is an intrinsic feature of living cells that allows spatiotemporal control over the biochemical pathways expressed in them. Over the years, a library of compartmentalized systems has been generated, which includes nano to micrometer sized biomimetic vesicles derived from lipids, amphiphilic block copolymers, peptides, and nanoparticles. Biocatalytic vesicles have been developed using a simple bag containing enzyme design of liposomes to multienzymes immobilized multi-vesicular compartments for artificial cell generation. Additionally, enzymes were also entrapped in membrane-less coacervate droplets to mimic the cytoplasmic macromolecular crowding mechanisms. Here, we have discussed different types of single and multicompartment systems, emphasizing their recent developments as biocatalytic self-assembled structures using recent examples. Importantly, we have summarized the strategies in the development of the self-assembled structure to improvise their adaptivity and flexibility for enzyme immobilization. Finally, we have presented the use of biocatalytic assemblies in mimicking different aspects of living cells, which further carves the path for the engineering of a minimal cell.

Construction of Hybrid Bi-microcompartments with Exocytosis-Inspired Behavior toward Fast Temperature-Modulated Transportation of Living Organisms

Inspired by the unique characteristics of living cells, the creation of life-inspired functional ensembles is a rapidly expanding research topic, enabling transformative applications in various disciplines. Herein, we report a facile method for the fabrication of phospholipid and block copolymer hybrid bi-microcompartments via spontaneous asymmetric assembly at the water/tributyrin interface, whereby the temperature-mediated dewetting of the inner microcompartments allowed for exocytosis to occur in the constructed system. The exocytosis location and commencement time could be controlled by the buoyancy of the inner microcompartment and temperature, respectively. Furthermore, the constructed bi-microcompartments showed excellent biocompatibility and a universal loading capacity toward cargoes of widely ranging sizes; thus, the proliferation and temperature-programmed transportation of living organisms was achieved. Our results highlight opportunities for the development of complex mesoscale dynamic ensembles with life-inspired behaviors and provide a novel platform for on-demand transport of various living organisms.

Design of Switchable Enzyme Carriers Based on Stimuli-Responsive Porous Polymer Membranes for Bioapplications

Design of efficient enzyme carriers, where enzymes are conjugated to supports, has become an attractive research avenue. Immobilized enzymes are advantageous for practical applications because of their convenience in handling, ease of separation, and good reusability. However, the main challenge is that these traditional enzyme carriers are unable to regulate the enzymolysis efficiency or to protect the enzymes from proteolytic degradation, which restricts their effectiveness of enzymes in bioapplications. Enlightened by the stimuli-responsive channels in the natural cell membranes, conjugation of the enzymes within flat-sheet stimuli-responsive porous polymer membranes (SR-PPMs) as artificial cell membranes is an efficient strategy for circumventing this challenge. Controlled by the external stimuli, the multifunctional polymer chains, which are incorporated within the membranes and attached to the enzyme, change their structures to defend the enzyme from the external environmental disturbances and degradation by proteinases. Specifically, smart SR-PPM enzyme carriers (SR-PPMECs) not only permit convective substrate transfer through the accessible porous network, dramatically improving enzymolysis efficiency due to the adjustable pore sizes and the confinement effect, but they also act as molecular switches for regulating its permeability and selectivity. In this review, the concept of SR-PPMECs is presented. It covers the latest developments in design strategies of flat-sheet SR-PPFMs, fabrication protocols of SR-PPFMECs, strategies for the regulation of enzymolysis efficiency, and their cutting-edge bioapplications.

A Floating Mold Technique for the Programmed Assembly of Protocells into Protocellular Materials Capable of Non-Equilibrium Biochemical Sensing

Despite important breakthroughs in bottom-up synthetic biology, a major challenge still remains the construction of free-standing, macroscopic, and robust materials from protocell building blocks that are stable in water and capable of emergent behaviors. Herein, a new floating mold technique for the fabrication of millimeter- to centimeter-sized protocellular materials (PCMs) of any shape that overcomes most of the current challenges in prototissue engineering is reported. Significantly, this technique also allows for the generation of 2D periodic arrays of PCMs that display an emergent non-equilibrium spatiotemporal sensing behavior. These arrays are capable of collectively translating the information provided by the external environment and are encoded in the form of propagating reaction-diffusion fronts into a readable dynamic signal output. Overall, the methodology opens up a route to the fabrication of macroscopic and robust tissue-like materials with emergent behaviors, providing a new paradigm of bottom-up synthetic biology and biomimetic materials science.

Research progress of using micro/nanomotors in the detection and therapy of diseases related to the blood environment

Micro/nanomotors bring new possibilities for the detection and therapy of diseases related to the blood environment with their unique motion effect. This work reviews the research progress of using micro/nanomotors in the detection and therapy of diseases related to the blood environment. First, we outline the advantages of using micro/nanomotors in blood-related disease detection. To be specific, the motion capability of micro/nanomotors can increase plasma or blood fluid convection and accelerate the interaction between the sample and the capture probe. This allows the effective reduction of the amount of reagents and treatment steps. Therefore, the application of micro/nanomotors significantly improves the analytical performance. Second, we discuss the key challenges and future prospects of micro/nanomotors in the treatment of blood-environment related diseases. It is very important to design a unique treatment plan according to the etiology and specific microenvironment of the disease. The next generation of micro/nanomotors is expected to bring exciting progress to the detection and therapy of blood-environment related diseases.

A Novel Acid-Degradable PEG Crosslinker for the Fabrication of pH-Responsive Soft Materials

The design and synthesis of a novel acid-degradable polyethylene glycol-based N-hydroxysuccinimide (NHS) ester-activated crosslinker is reported. The crosslinker is reactive towards nucleophiles and features a central ketal functional group that is stable at pH > 7.5 and rapidly hydrolyses at pH > 6.0. The crosslinker is used to (i) fabricate acid-degradable polysaccharide hydrogels that exhibit controlled degradation upon exposure to an acidic environment or via endogenous enzyme activity; and (ii) construct hydrogel-filled protein-polymer microcompartments (termed proteinosomes) capable of pH-dependent membrane disassembly. Taken together the results provide new opportunities for the fabrication of pH-responsive soft materials with potential applications in drug delivery, tissue engineering, and soft-matter bioengineering.

Dual-responsive polymersomes as anticancer drug carriers for the co-delivery of doxorubicin and paclitaxel

Multi stimuli-responsive polymersomes are in high demand as smart drug carriers, particularly for the treatment of complex cancers. However, most polymersomes have multi-responsiveness that does not affect each other and focus on single drug loading. Here, we have designed photo-crosslinked temperature and pH dual-responsive polymersomes by the self-assembly of a triblock polymer of methoxyl poly(ethylene glycol)-b-poly(N-isopropylacrylamide)-b-poly[2-(diethylamino)ethyl methacrylate-co-2-hydroxy-4-(methacryloyloxy)benzophenone] (mPEG-b-PNIPAM-b-P(DEAEMA-co-BMA)) synthesized via reversible addition-fragmentation chain transfer polymerization (RAFT). The dual-responsive polymersomes had a layered membrane, resulting in tunable permeability. Importantly, the polymersomes were proved to have a pH-controlled temperature-responsiveness. A hydrophilic-hydrophobic drug pair (doxorubicin hydrochloride, DOX, and paclitaxel, PTX) could be co-encapsulated in the fabricated polymersomes. The membrane permeability based on its layered structure was triggered by the change in temperature and pH to permit the separate control on the release of DOX and PTX. In a simulated tumor microenvironment, DOX and PTX encapsulated in the polymersomes could take effect for a relatively longer period and could work synergistically. Thus, the photo-crosslinked and dual-responsive polymersomes can be considered as promising drug carriers in the field of tumor combination chemotherapy.