Multifunctional protein microparticles for medical applications

Multifunctional Micromachines Constructed by Combining Multiple Protein-Based Components with Different Functions

Untethered mobile micromachines have considerable potential to realize more effective and minimally invasive medicine. Although diverse medical micromachines have been reported over the past few decades, these machines were developed for performing only specific tasks and the functions imparted to them were limited to a few. Hence, the methodologies for imparting a wide variety of functions to machines have not been fully explored. In this study, a novel construction strategy for the multifunctional micromachines is presented, where a specific function can be added to the machine in one step by directly combining the protein-based component, possessing the biological function of constituent proteins, to an arbitrary position of the machine by using an inkjet printing technique. As a proof-of-concept demonstration, various types of machines were constructed by combining multiple components with different functions. These constructed machines successfully performed functions as diverse as enzyme-powered self-propulsion, collection of target objects, including the bilirubin and living cells, enzyme-mediated conversion of substrate molecules to different ones, magnetic guidance, and release of anti-inflammatory drug diapocynin. The study's progressive approach as well as multifunctional and biocompatible machines composed of proteins will profoundly impact the development of intelligent machines equipped with multiplex sophisticated functionalities.

Potential of the Coordinated Actions of Multiple Protein-Based Micromachines for Medical Applications

Untethered mobile micromachines hold great promise in the development of effective and minimally invasive therapies. Although diverse medical micromachines for specific applications have been developed over the past few decades, the coordinated action of multiple machines with different functions remains largely unexplored. In this study, we created three types of biocompatible micromachines using proteins and demonstrated the potential of their coordinated action for medical applications. As a proof of concept, we demonstrated neural replacement therapy, in which neuroblastomas were killed by using an anticancer prodrug and the first machine that contains enzymes, enabling the conversion of the prodrug into a cytotoxic drug. Subsequently, a second machine composed of extracellular matrix was placed on the dead cancer cells to provide a suitable environment for cell adhesion, on which embryonic stem (ES) cells and stromal cells that promote neural differentiation of stem cells were attached by using third machines capable of delivering cells to target positions with desired patterns. As a result, neuroblastomas were replaced with novel healthy neurons derived from ES cells by teaming multiple protein-based machines. We believe that this work highlights the potential of heterogeneous machine groups for medical treatment and the utility of highly biocompatible and functional micromachines made from proteins, representing an important step forward in building more sophisticated micromachine-based therapies.

Superior Adhesion of a Multifunctional Protein-Based Micropatch to Intestinal Tissue by Harnessing the Hydrophobic Effect

Drug delivery systems comprising drug carriers capable of adhering to intestinal tissue have considerable potential to realize more sophisticated systemic drug delivery and topical drug treatments in the intestinal tract. The development of innovative strategies for improving the adhesion efficiency of carriers is of high importance for the advancement of this field. Herein, a novel approach to achieving high adhesion efficiency of drug carriers is presented, where the accessibility of the carrier to the intestinal surface and its subsequent adhesion to the intestinal tissue are promoted by utilizing the thermodynamic tendency of the hydrophobic carrier and its dispersion solvent, triacetin, to be excluded from the aqueous environment. Drug carriers are fabricated using proteins, imparting multiple functions, including drug release and the removal of reactive oxygen species (ROS). Results of ex vivo studies indicate that this multifunctional protein-based carrier, "protein micropatch," adheres to various mouse intestinal tissues, including the small intestine, colon, and inflamed colon, with high efficiency. Furthermore, protein micropatches, administered to mice via oral or rectal routes, successfully adhere to the intestinal tract. This approach and the highly functionalized carrier described in the study have the potential to significantly contribute to the development of bioadhesive carrier-based drug delivery systems.

Biocatalytic CsPbX3 Perovskite Nanocrystals: A Self-Reporting Nanoprobe for Metabolism Analysis

CsPbX₃ perovskite nanocrystals (NCs), with excellent optical properties, have drawn considerable attention in recent years. However, they also suffer from inherent vulnerability and hydrolysis, causing the new understanding or new applications to be difficultly explored. Herein, for the first time, it is discovered that the phospholipid membrane (PM)-coated CsPbX₃ NCs have intrinsic biocatalytic activity. Different from other peroxidase-like nanozymes relying on extra chromogenic reagents, the PM-CsPbX₃ NCs can be used as a self-reporting nanoprobe, allowing an "add-to-answer" detection model. Notably, the fluorescence of PM-CsPbX₃ NCs can be rapidly quenched by adding H₂ O₂ and then be restored by removing excess H₂ O₂ . Initiated from this unexpected observation, the PM-CsPbX₃ NCs can be explored to prepare multi-color bioinks and metabolite-responsive paper analytical devices, demonstrating the great potential of CsPbX₃ NCs in bioanalysis. This is the first report on the discovery of nanozyme-like property of all-inorganic CsPbX₃ perovskite NCs, which adds another piece to the nanozyme puzzle and opens new avenues for in vitro disease diagnostics.

Freeze-Dried Matrices Composed of Degradable Polymers with Surfactant-Loaded Microparticles Based on Pectin and Sodium Alginate

Gelatin/polyvinylpyrrolidone/hydroxyethyl cellulose/glycerol porous matrices with microspheres made of sodium alginate or pectin and sodium alginate were produced. A surfactant was loaded into these microparticles. The microspheres were characterized using optical microscopy, scanning electron microscopy SEM, and laser diffraction particle size analyzer. For the matrices, the density, porosity, swelling capacity, dissolution in phosphate saline buffer were determined and SEM, mechanical, and thermogravimetric studies were applied. The results showed that the size of the two-component microspheres was slightly larger than that of single-ingredient microparticles. The images confirmed the spherical shape of the microparticles. The prepared matrices had high water uptake ability and porosity due to the presence of hydrophilic polymers. The presence of microparticles in the matrices caused a decrease in these parameters. Degradation of the composites with the microspheres was significantly faster than the matrix without them. The addition of microparticles increased the stiffness and toughness of the prepared materials. The efficiency of the thermal decomposition main stage was reduced in the samples with microspheres, whereas a char residue increased in these composites.

Recent Advances in Patterning Natural Polymers: From Nanofabrication Techniques to Applications

The development of a flexible and efficient strategy to precisely fabricate polymer patterns is increasingly significant for many research areas, especially for cell biology, pharmaceutical science, tissue engineering, soft photonics, and bioelectronics. Recent advances of patterning natural polymers using various nanofabrication techniques, including photolithography, electron-beam lithography, dip-pen nanolithography, inkjet printing, soft lithography, and nanoimprint lithography are discussed here. Integrating nanofabrication techniques with naturally derived macromolecules provides a feasible route for transforming these polymer materials into versatile and sophisticated devices while maintaining their intrinsic and excellent properties. Furthermore, the corresponding applications of these natural polymer patterns generated by the above techniques are elaborated. In the end, a summary of this promising research field is offered and an outlook for the future is given. It is expected that advances in precise spatial patterns of natural polymers would provide new avenues for various applications, such as tissue engineering, flexible electronics, biomedical diagnosis, and soft photonics.

Conformational Transitions upon Maturation Rule Surface and pH-Responsiveness of α-Lactalbumin Microparticulates

De novo designed protein supramolecular structures are nowadays attracting much interest as highly performing biomaterials. While a clear advantage is provided by the intrinsic biocompatibility and biodegradability of protein and peptide building blocks, developing sustainable and green bottom up approaches for finely tuning the material properties still remains a challenge. Here, we present an experimental study on the formation of protein microparticles in the form of particulates from the protein α-lactalbumin using bulk mixing in water solution and high temperature. Once formed, the structure and stability of these spherical protein condensates change upon further thermal incubation while the size of aggregates does not significantly increase. Combining advanced microscopy and spectroscopy methods, we prove that this process, named maturation, is characterized by a gradual increase of amyloid-like structure in protein particulates, an enhancement in surface roughness and in molecular compactness, providing a higher stability and resistance of the structure in acidic environments. When dissolved at pH 2, early stage particulates disassemble into a homogeneous population of small oligomers, while the late stage particulates remain unaffected. Particulates at the intermediate stage of maturation partially disassemble into a heterogeneous population of fragments. Importantly, differently matured microparticles show different features when loading a model lipophilic molecule. Our findings suggest conformational transitions localized at the interface as a key step in the maturation of amyloid protein condensates, promoting this phenomenon as an intrinsic knob to tailor the properties of protein microparticles formed via bulk mixing in aqueous solution. This provides a simple and sustainable platform for the design and realization of protein microparticles for tailored applications.

Aptamer Hybrid Nanocomplexes as Targeting Components for Antibiotic/Gene Delivery Systems and Diagnostics: A Review

With the passage of time and more advanced societies, there is a greater emergence and incidence of disease and necessity for improved treatments. In this respect, nowadays, aptamers, with their better efficiency at diagnosing and treating diseases than antibodies, are at the center of attention. Here, in this review, we first investigate aptamer function in various fields (such as the detection and remedy of pathogens, modification of nanoparticles, antibiotic delivery and gene delivery). Then, we present aptamer-conjugated nanocomplexes as the main and efficient factor in gene delivery. Finally, we focus on the targeted co-delivery of genes and drugs by nanocomplexes, as a new exciting approach for cancer treatment in the decades ahead to meet our growing societal needs.

Conformable self-assembling amyloid protein coatings with genetically programmable functionality

Functional coating materials have found broad technological applications in diverse fields. Despite recent advances, few coating materials simultaneously achieve robustness and substrate independence while still retaining the capacity for genetically encodable functionalities. Here, we report Escherichia coli biofilm-inspired protein nanofiber coatings that simultaneously exhibit substrate independence, resistance to organic solvents, and programmable functionalities. The intrinsic surface adherence of CsgA amyloid proteins, along with a benign solution-based fabrication approach, facilitates forming nanofiber coatings on virtually any surface with varied compositions, sizes, shapes, and structures. In addition, the typical amyloid structures endow the nanofiber coatings with outstanding robustness. On the basis of their genetically engineerable functionality, our nanofiber coatings can also seamlessly participate in functionalization processes, including gold enhancement, diverse protein conjugations, and DNA binding, thus enabling a variety of proof-of-concept applications, including electronic devices, enzyme immobilization, and microfluidic bacterial sensors. We envision that our coatings can drive advances in electronics, biocatalysis, particle engineering, and biomedicine.

Antibody immobilization technique using protein film for high stability and orientation control of the immobilized antibody

The development of antibody immobilization techniques is essential for creating antibody-based biomaterials. Although numerous methods for antibody immobilization have been demonstrated, low stability and disordered orientation of the immobilized antibody remain an important problem. In this work, an original antibody immobilization technique using a protein film, which achieved a high stability and orientation control of the immobilized antibody, has been described. In this method, an antibody-immobilized albumin film was prepared by adding the cross-linked albumin solution to the substrate, where antibodies were attached in uniform orientation, followed by subsequent drying, and detaching the formed film from the substrate by heating at 120 °C in a dry state. Antibodies in the film showed high antigen-binding capacity, at a level comparable to the oriented immobilized antibody using protein G. The stability of antibodies in the film was found to be significantly high; their antigen-binding capacity was completely retained even after storage at 40 °C in a dry state for one month. Thus, this approach provides useful information to immobilize the antibody on solid surfaces while controlling its orientation and increasing its stability.