Nanoporous Metal-Phenolic Particles as Ultrasound Imaging Probes for Hydrogen Peroxide

Catalytic Nanoparticles in Biomedical Applications: Exploiting Advanced Nanozymes for Therapeutics and Diagnostics

Catalytic nanoparticles (CNPs) as heterogeneous catalyst reveals superior activity due to their physio-chemical features, such as high surface-to-volume ratio and unique optical, electric, and magnetic properties. The CNPs, based on their physio-chemical nature, can either increase the reactive oxygen species (ROS) level for tumor and antibacterial therapy or eliminate the ROS for cytoprotection, anti-inflammation, and anti-aging. In addition, the catalytic activity of nanozymes can specifically trigger a specific reaction accompanied by the optical feature change, presenting the feasibility of biosensor and bioimaging applications. Undoubtedly, CNPs play a pivotal role in pushing the evolution of technologies in medical and clinical fields, and advanced strategies and nanomaterials rely on the input of chemical experts to develop. Herein, a systematic and comprehensive review of the challenges and recent development of CNPs for biomedical applications is presented from the viewpoint of advanced nanomaterial with unique catalytic activity and additional functions. Furthermore, the biosafety issue of applying biodegradable and non-biodegradable nanozymes and future perspectives are critically discussed to guide a promising direction in developing span-new nanozymes and more intelligent strategies for overcoming the current clinical limitations.

Ultrasound-Based Micro-/Nanosystems for Biomedical Applications

Due to the intrinsic non-invasive nature, cost-effectiveness, high safety, and real-time capabilities, besides diagnostic imaging, ultrasound as a typical mechanical wave has been extensively developed as a physical tool for versatile biomedical applications. Especially, the prosperity of nanotechnology and nanomedicine invigorates the landscape of ultrasound-based medicine. The unprecedented surge in research enthusiasm and dedicated efforts have led to a mass of multifunctional micro-/nanosystems being applied in ultrasound biomedicine, facilitating precise diagnosis, effective treatment, and personalized theranostics. The effective deployment of versatile ultrasound-based micro-/nanosystems in biomedical applications is rooted in a profound understanding of the relationship among composition, structure, property, bioactivity, application, and performance. In this comprehensive review, we elaborate on the general principles regarding the design, synthesis, functionalization, and optimization of ultrasound-based micro-/nanosystems for abundant biomedical applications. In particular, recent advancements in ultrasound-based micro-/nanosystems for diagnostic imaging are meticulously summarized. Furthermore, we systematically elucidate state-of-the-art studies concerning recent progress in ultrasound-based micro-/nanosystems for therapeutic applications targeting various pathological abnormalities including cancer, bacterial infection, brain diseases, cardiovascular diseases, and metabolic diseases. Finally, we conclude and provide an outlook on this research field with an in-depth discussion of the challenges faced and future developments for further extensive clinical translation and application.

Self-Healing Guar Gum-Based Nanocomposite Hydrogel Promotes Infected Wound Healing through Photothermal Antibacterial Therapy

Preventing bacterial infections is a crucial aspect of wound healing. There is an urgent need for multifunctional biomaterials without antibiotics to promote wound healing. In this study, we fabricated a guar gum (GG)-based nanocomposite hydrogel, termed GBTF, which exhibited photothermal antibacterial therapy for infected wound healing. The GBTF hydrogel formed a cross-linked network through dynamic borate/diol interactions between GG and borax, thereby exhibiting simultaneously self-healing, adaptable, and injectable properties. Additionally, tannic acid (TA)/Fe3+ nanocomplexes (NCs) were incorporated into the hydrogel to confer photothermal antibacterial properties. Under the irradiation of an 808 nm near-infrared laser, the TA/Fe3+ NCs in the hydrogel could rapidly generate heat, leading to the disruption of bacterial cell membranes and subsequent bacterial eradication. Furthermore, the hydrogels exhibited good cytocompatibility and hemocompatibility, making them a precandidate for preclinical and clinical applications. Finally, they could significantly promote bacteria-infected wound healing by reducing bacterial viability, accelerating collagen deposition, and promoting epithelial remodeling. Therefore, the multifunctional GBTF hydrogel, which was composed entirely of natural substances including guar gum, borax, and polyphenol/ferric ion NCs, showed great potential for regenerating infected skin wounds in clinical applications.

Arginine-Nanoenzyme with Timely Angiogenesis for Promoting Diabetic Wound Healing

The successful treatment of diabetic wounds requires strategies that promote anti-inflammation, angiogenesis, and re-epithelialization of the wound. Excessive oxidative stress in diabetic ulcers (DUs) inhibits cell proliferation and hinders timely vascular formation and macrophage polarization from pro-inflammatory M1 to anti-inflammatory M2, resulting in a persistent inflammatory environment and a nonhealing wound. We designed arginine-nanoenzyme (FTA) with mimic-catalase and arginine-loading. 2,3,4-trihydroxy benzaldehyde and arginine (Arg) were connected by a Schiff base bond, and the nanoassembly of Arg to FTA was driven by the coordination force between a ferric ion and polyphenol and noncovalent bond force such as a hydrogen bond. FTA could remove excess reactive oxygen species at the wound site in situ and convert it to oxygen to improve hypoxia. Meanwhile, Arg was released and catalytically metabolized by NO synthase in M1 to promote vascular repair in the early phase. In the late phase, the metabolite of Arg catalyzed by arginase in M2 was mainly ornithine, which played a vital role in promoting tissue repair, which implemented angiogenesis timely and prevented hypertrophic scars. Mechanistically, FTA activated the cAMP signaling pathway combined with reducing inflammation and ameliorating angiogenesis, which resulted in excellent therapeutic effects on a DU mice model.

The Emerging Landscape for Combating Resistance Associated with Energy-Based Therapies via Nanomedicine

Cancer represents a serious disease with significant implications for public health, imposing substantial economic burden and negative societal consequences. Compared to conventional cancer treatments, such as surgery and chemotherapy, energy-based therapies (ET) based on athermal and thermal ablation provide distinct advantages, including minimally invasive procedures and rapid postoperative recovery. Nevertheless, due to the complex pathophysiology of many solid tumors, the therapeutic effectiveness of ET is often limited. Nanotechnology offers unique opportunities by enabling facile material designs, tunable physicochemical properties, and excellent biocompatibility, thereby further augmenting the outcomes of ET. Numerous nanomaterials have demonstrated the ability to overcome intrinsic therapeutic resistance associated with ET, leading to improved antitumor responses. This comprehensive review systematically summarizes the underlying mechanisms of ET-associated resistance (ETR) and highlights representative applications of nanoplatforms used to mitigate ETR. Overall, this review emphasizes the recent advances in the field and presents a detailed account of novel nanomaterial designs in combating ETR, along with efforts aimed at facilitating their clinical translation.

Recent Advances of Metal-Polyphenol Coordination Polymers for Biomedical Applications

Nanomedicine has provided cutting-edge technologies and innovative methods for modern biomedical research, offering unprecedented opportunities to tackle crucial biomedical issues. Nanomaterials with unique structures and properties can integrate multiple functions to achieve more precise diagnosis and treatment, making up for the shortcomings of traditional treatment methods. Among them, metal-polyphenol coordination polymers (MPCPs), composed of metal ions and phenolic ligands, are considered as ideal nanoplatforms for disease diagnosis and treatment. Recently, MPCPs have been extensively investigated in the field of biomedicine due to their facile synthesis, adjustable structures, and excellent biocompatibility, as well as pH-responsiveness. In this review, the classification of various MPCPs and their fabrication strategies are firstly summarized. Then, their significant achievements in the biomedical field such as biosensing, drug delivery, bioimaging, tumor therapy, and antibacterial applications are highlighted. Finally, the main limitations and outlooks regarding MPCPs are discussed.

Multi-Wavelength Light-Responsive Metal-Phenolic Network-Based Microrobots for Reactive Species Scavenging

Light-driven microrobots with different propulsion mechanisms have attracted great attention in microrobot synthesis and applications. However, current systems rely heavily on precious metals, using a complex synthesis process and limited working wavelength. It is therefore of great interest to fabricate microrobots that can be driven by multi-wavelength irradiation and with simple components. Here, metal-phenolic network (MPN)-based microrobots are synthesized using a sacrificial polystyrene bead template and an extra capping is added to regulate their symmetry. The hollow MPN microrobots with different layers of capping are capable of moving under both near-infrared (NIR) irradiation and ultraviolet (UV) irradiation, without fuel. The velocity of the microrobots under irradiation is altered by the thickness of the asymmetric capping and their motion could be manipulated remotely by switching the NIR or UV irradiation on and off. With light-driven mobility, the reactive oxygen and nitrogen species (RONS) scavenging activity of the microrobots is significantly increased. Therefore, this proposed microrobot system provides a synthesis strategy to develop asymmetric light-navigated microrobots for future medical treatment with tunable structure, multi-wavelength light-responsive mobility, and great RONS scavenging capacity.

Multifunctional Dual Cross-Linked Bioadhesive Patch with Low Immunogenic Response and Wet Tissues Adhesion

The development of bioadhesives is an important, yet challenging task as seemingly mutually exclusive properties need to be combined in one material, that is, strong adhesion, water resistance, and high biocompatibility. Here, a biocompatible and biodegradable protein-based bioadhesive patch (PBP) with high adhesion strength and low immunogenic response is reported. PBP exists as a strong adhesion for biological surfaces, which is higher than some conventional bioadhesives (i.e., polyethylene glycol and fibrin). Robust adhesion and strength are realized through the removal of interfacial water and fast formation of multiple supramolecular interactions induced by metal ions. The PBP's high biocompatibility is evaluated and immunogenic response in vitro and in vivo is neglected. The strong adhesion on soft biological tissues qualifies the PBP as biomedical glue outperforming some commercial products for applications in hemostasis performance, accelerated wound healing, and sealing of defected organs, anticipating to be useful as a tissue adhesive and sealant.

Metal-Phenolic Networks as Versatile Coating Materials for Biomedical Applications

Polyphenols are naturally derived organic compounds that have long been used as food additives, antioxidants, and adhesives owing to their intrinsic physicochemical properties. Recently, there has been growing interest in the fabrication of coordination networks based on the self-assembly of polyphenols and metal ions, termed metal-phenolic networks (MPNs), for multiple biological applications including bioimaging, drug delivery, and cell encapsulation. The as-synthesized MPN complexes feature pH responsiveness, controllable size and rigidity, and tunable permeability based on the choice of polyphenol-metal ion pairs. The aim of this Review is to introduce the physicochemical properties of MPNs, highlight their recent biological applications in cancer theranostics and single-cell encapsulation, and discuss the future utility of MPNs for biomedical applications.

Nanostructured particles assembled from natural building blocks for advanced therapies

Advanced treatments based on immune system manipulation, gene transcription and regulation, specific organ and cell targeting, and/or photon energy conversion have emerged as promising therapeutic strategies against a range of challenging diseases. Naturally derived macromolecules (e.g., proteins, lipids, polysaccharides, and polyphenols) have increasingly found use as fundamental building blocks for nanostructured particles as their advantageous properties, including biocompatibility, biodegradability, inherent bioactivity, and diverse chemical properties make them suitable for advanced therapeutic applications. This review provides a timely and comprehensive summary of the use of a broad range of natural building blocks in the rapidly developing field of advanced therapeutics with insights specific to nanostructured particles. We focus on an up-to-date overview of the assembly of nanostructured particles using natural building blocks and summarize their key scientific and preclinical milestones for advanced therapies, including adoptive cell therapy, immunotherapy, gene therapy, active targeted drug delivery, photoacoustic therapy and imaging, photothermal therapy, and combinational therapy. A cross-comparison of the advantages and disadvantages of different natural building blocks are highlighted to elucidate the key design principles for such bio-derived nanoparticles toward improving their performance and adoption. Current challenges and future research directions are also discussed, which will accelerate our understanding of designing, engineering, and applying nanostructured particles for advanced therapies.

Pharmacokinetic/Pharmacodynamic Determinations of Iron-tannic Molecular Nanoparticles with its Implication in MR Imaging and Enhancement of Liver Clearance

Assessment and enhancement of liver clearance are promising strategies for protection of liver from various liver diseases. Iron-tannic nanoparticles (FTs) were previously considered as imageable autophagic enhancers with biodegradation potential. Herein, we present a new approach for utilizing Iron-tannic nanoparticles (FTs) as a tool for imaging and increasing liver clearance. Pharmacokinetic profiling suggested that FTs were initially found in blood circulation and thereafter were distributed to the liver. By using MR imaging (T1 weighted), maximum MRI signal enhancement was found to occur after 30 minutes post-injection (i.v.) and gradually decreased afterward. Decreasing MRI signal may be due to FTs metabolism by the liver. By assessing imaging-derived pharmacokinetics, we can simply determine the rate constant of liver degradation of FTs. Potentially, we might use this parameter to monitor liver function, where its clearance is of concern. Once functional implication of FTs in liver clearance was investigated, FTs were found to induce hepatocyte autophagy along with activation of lysosomes. Consequently, the hepatocytes were capable of efficiently clearing cellular debris. From these results, it is clear that FTs should be considered as a molecular tool for quantitative MRI-derived liver function assessment, and for enhancing clearance function in liver parenchyma. Hopefully, our findings will pave the way to develop new strategies for non-invasive assessment and enhancement of liver clearance.

Controllable Synthesis of Polyphenol Spheres via Amine-Catalyzed Polymerization-Induced Self-Assembly

A facile and general strategy for preparing uniform and multifunctional polyphenol-based colloidal particles through amine-catalyzed polymerization-induced self-assembly is described. The size and interfacial adhesion of polyphenol spheres can be easily controlled over a wide range via adjusting the concentration of the cosolvent and monomer. Moreover, the polyphenol spheres showed excellent thermal and chemical stability and highly active properties and could efficiently deplete the reactive oxygen species (ROS), which are helpful for in vivo ROS regulation for inflammatory therapeutic. The accessible and versatile method provides a feasible way for the rational engineering of multifunctional polyphenol spheres, which have great potential in many fields.

Ultrasonic particles: An approach for targeted gene delivery

Gene therapy has been widely investigated for the treatment of genetic, acquired, and infectious diseases. Pioneering work utilized viral vectors; however, these are suspected of causing serious adverse events, resulting in the termination of several clinical trials. Non-viral vectors, such as lipid nanoparticles, have attracted significant interest, mainly due to their successful use in vaccines in the current COVID-19 pandemic. Although they allow safe delivery, they come with the disadvantage of off-target delivery. The application of ultrasound to ultrasound-sensitive particles allows for a direct, site-specific transfer of genetic materials into the organ/site of interest. This process, termed ultrasound-targeted gene delivery (UTGD), also increases cell membrane permeability and enhances gene uptake. This review focuses on the advances in ultrasound and the development of ultrasonic particles for UTGD across a range of diseases. Furthermore, we discuss the limitations and future perspectives of UTGD.

Enhancing the drug sensitivity of antibiotics on drug-resistant bacteria via the photothermal effect of FeTGNPs

The growing problem of bacterial resistance caused by the abuse of antibiotics is a serious challenge for the world. In order to make the clinically available antibiotics regain their bactericidal effect, our study introduced photothermal therapy (PTT) to assist antibiotics to annihilate drug-resistant bacteria. To achieve the synergistic effect, nanoparticles (FeTGNPs) with an antibiotic core (gatifloxacin complexing with tannins) and a photothermal shell (ferric iron coordinating with tannins) were prepared directly in aqueous solution by a convenient yet efficient one-pot synthesis. The excellent photothermal properties of the shell of FeTGNPs were used to break the mechanism of bacterial resistance, and the sustained-release of gatifloxacin from the core regained the killing effect against drug-resistant bacteria. From the results of antibacterial experiments, with the synergistic effect of APTT and antibiotics, FeTGNPs (400 μg/mL) could effectively kill methicillin-resistant Staphylococcus aureus (sterilizing rate up to 96.5 %) and gatifloxacin-resistant Staphylococcus aureus (sterilizing rate up to 98.7 %) than equivalent antibiotics. Moreover, under slightly acidic microenvironment, such as infection area, gatifloxacin could accelerate its release from the core of FeTGNPs. Therefore, FeTGNPs would be a highly effective antibacterial agent against drug-resistant bacterial infections in the future.

Recent Advances in Metal-Phenolic Networks for Cancer Theranostics

Nanomedicine integrates different functional materials to realize the customization of carriers, aiming at increasing the cancer therapeutic efficacy and reducing the off-target toxicity. However, efforts on developing new drug carriers that combine precise diagnosis and accurate treatment have met challenges of uneasy synthesis, poor stability, difficult metabolism, and high cytotoxicity. Metal-phenolic networks (MPNs), making use of the coordination between phenolic ligands and metal ions, have emerged as promising candidates for nanomedicine, most notably through the service as multifunctional theranostic nanoplatforms. MPNs present unique properties, such as rapid preparation, negligible cytotoxicity, and pH responsiveness. Additionally, MPNs can be further modified and functionalized to meet specific application requirements. Here, the classification of polyphenols is first summarized, followed by the introduction of the properties and preparation strategies of MPNs. Then, their recent advances in biomedical sciences including bioimaging and anti-tumor therapies are highlighted. Finally, the main limitations, challenges, and outlooks regarding MPNs are raised and discussed.

Mitochondria-targeted photoacoustic probe for imaging of hydrogen peroxide in inflamed mouse model

In this chapter, we gave a brief introduction of hydrogen peroxide (H₂O₂) and its existing analytical methods and described the need of mitochondria-targeted photoacoustic (PA) probe for H₂O₂ detection in vivo. Then we provided the detailed protocols for the design and characterization of a mitochondria-targeted PA probe (TPP-HCy-BOH) to visualize H₂O₂in vivo, which was developed in our previous work. Compared to control probe without mitochondria-targeted ability (HCy-BOH), TPP-HCy-BOH could efficiently accumulate in mitochondria and activate its PA signals toward overproduced H₂O₂ in inflamed mouse model with higher PA sensitivity.

Metal-phenolic networks: facile assembled complexes for cancer theranostics

In recent years, metal-phenolic networks (MPNs) have attracted increasing attention for the engineering of multi-functional platforms because of their easy fabrication processes, excellent physicochemical properties, outstanding biocompatibility, and promising theranostic applications. In this review, we summarize recent progress in the design, synthesis, shape-control, biocompatibility evaluation, and potential theranostic applications of MPNs, especially for cancer theranostics. First, we provide an overview of various MPN systems, relevant self-assembly procedures, and shape-controllable preparation. The in vitro and in vivo biocompatibility evaluation of MPNs is also discussed, including co-incubation viability, adhesion, bio-distribution, and inflammation. Finally, we highlight the significant achievements of various MPNs for cancer theranostics, such as tumor imaging, drug delivery, photothermal therapy, radiotherapy, and chemo- and photo-dynamic therapy. This review provides a comprehensive background on the design and controllable synthesis, in vitro and in vivo biocompatibility evaluation, applications of MPNs as cancer theranostic agents, and presents an overview of the most up-to-date achievements in this field.

Dynamic Solid-State Ultrasound Contrast Agent for Monitoring pH Fluctuations In Vivo

The key challenge for in vivo biosensing is to design biomarker-responsive contrast agents that can be readily detected and monitored by broadly available biomedical imaging modalities. While a range of biosensors have been designed for optical, photoacoustic, and magnetic resonance imaging (MRI) modalities, technical challenges have hindered the development of ultrasound biosensors, even though ultrasound is widely available, portable, safe, and capable of both surface and deep tissue imaging. Typically, contrast-enhanced ultrasound imaging is generated by gas-filled microbubbles. However, they suffer from short imaging times because of the diffusion of the gas into the surrounding media. This demands an alternate approach to generate nanosensors that reveal pH-specific changes in ultrasound contrast in biological environments. Silica cores were coated with pH-responsive poly(methacrylic acid) (PMA_SH) in a layer-by-layer (LbL) approach and subsequently covered in a porous organosilica shell. Transmission electron microscopy (TEM) and confocal laser scanning microscopy (CLSM) were employed to monitor the successful fabrication of multilayered particles and prove the pH-dependent shrinkage/swelling of the PMA_SH layer. This demonstrates that reduction in pH below healthy physiological levels resulted in significant increases in ultrasound contrast, in gel phantoms, mouse cadaver tissue, and live mice. The future of such materials could be developed into a platform of biomarker-responsive ultrasound contrast agents for clinical applications.

Cobalt-Directed Assembly of Antibodies onto Metal-Phenolic Networks for Enhanced Particle Targeting

The orientation-specific immobilization of antibodies onto nanoparticles, to preserve antibody-antigen recognition, is a key challenge in developing targeted nanomedicines. Herein, we report the targeting ability of metal-phenolic network (MPN)-coated gold nanoparticles with surface-physisorbed antibodies against respective antigens. The MPN coatings were self-assembled from metal ions (Fe^III, Co^II, Cu^II, Ni^II, or Zn^II) cross-linked with tannic acid. Upon physisorption of antibodies, all particle systems exhibited enhanced association with target antigens, with Co^II systems demonstrating more than 2-fold greater association. These systems contained more metal atoms distributed in a way to specifically interact with antibodies, which were investigated by molecular dynamics simulations. A model antibody fragment crystallizable (Fc) region in solution with Co^II-tannic acid complexes revealed that the solvent-exposed Co^II can directly coordinate to the histidine-rich portion of the Fc region. This one-pot interaction suggests anchoring of the antibody Fc region to the MPN on nanoparticles, allowing for enhanced targeting.

Porous Inorganic and Hybrid Systems for Drug Delivery: Future Promise in Combatting Drug Resistance and Translation to Botanical Applications

BACKGROUND

Porous micro- and nanoparticles have the capacity to encapsulate a large quantity of therapeutics, making them promising delivery vehicles for a variety of applications. This review aims to highlight the latest development of inorganic and hybrid (inorganic/ organic) particles for drug delivery with an additional emphasis on combatting drug resistant cancer. We go one step further and discuss delivery applications beyond medicinal delivery, as there is generally a translation from medicinal delivery to botanic delivery after a short lag time.

METHODS

We undertook a search of relevant peer-reviewed publications. The quality of the relevant papers was appraised using standard tools. The characteristics of the papers are described herein, and the relevant material and therapeutic properties are discussed.

RESULTS

We discuss 4 classes of porous particles in terms of drug delivery and theranostics. We specifically focus on silica, calcium carbonate, metal-phenolic network, and metalorganic framework particles. Other relevant biomedically relevant applications are discussed and we highlight outstanding therapeutic results in the relevant literature.

CONCLUSION

The findings of this review confirm the importance of studying and utilizing porous particles for therapeutic delivery. Moreover, we show that the properties of porous particles that make them promising for medicinal drug delivery also make them promising candidates for agro-industrial applications.

Nanocatalytic Medicine

Catalysis and medicine are often considered as two independent research fields with their own respective scientific phenomena. Promoted by recent advances in nanochemistry, large numbers of nanocatalysts, such as nanozymes, photocatalysts, and electrocatalysts, have been applied in vivo to initiate catalytic reactions and modulate biological microenvironments for generating therapeutic effects. The rapid growth of research in biomedical applications of nanocatalysts has led to the concept of "nanocatalytic medicine," which is expected to promote the further advance of such a subdiscipline in nanomedicine. The high efficiency and selectivity of catalysis that chemists strived to achieve in the past century can be ingeniously translated into high efficacy and mitigated side effects in theranostics by using "nanocatalytic medicine" to steer catalytic reactions for optimized therapeutic outcomes. Here, the rationale behind the construction of nanocatalytic medicine is eludicated based on the essential reaction factors of catalytic reactions (catalysts, energy input, and reactant). Recent advances in this burgeoning field are then comprehensively presented and the mechanisms by which catalytic nanosystems are conferred with theranostic functions are discussed in detail. It is believed that such an emerging catalytic therapeutic modality will play a more important role in the field of nanomedicine.

Polyphenol-Based Particles for Theranostics

Polyphenols, due to their high biocompatibility and wide occurrence in nature, have attracted increasing attention in the engineering of functional materials ranging from films, particles, to bulk hydrogels. Colloidal particles, such as nanogels, hollow capsules, mesoporous particles and core-shell structures, have been fabricated from polyphenols or their derivatives with a series of polymeric or biomolecular compounds through various covalent and non-covalent interactions. These particles can be designed with specific properties or functionalities, including multi-responsiveness, radical scavenging capabilities, and targeting abilities. Moreover, a range of cargos (e.g., imaging agents, anticancer drugs, therapeutic peptides or proteins, and nucleic acid fragments) can be incorporated into these particles. These cargo-loaded carriers have shown their advantages in the diagnosis and treatment of diseases, especially of cancer. In this review, we summarize the assembly of polyphenol-based particles, including polydopamine (PDA) particles, metal-phenolic network (MPN)-based particles, and polymer-phenol particles, and their potential biomedical applications in various diagnostic and therapeutic applications.

Targeted Therapy against Metastatic Melanoma Based on Self-Assembled Metal-Phenolic Nanocomplexes Comprised of Green Tea Catechin

The targeted therapy of metastatic melanoma is an important yet challenging goal that has received only limited attention to date. Herein, green tea polyphenols, (-)-epigallocatechin-3-gallate (EGCG), and lanthanide metal ions (Sm3+) are used as building blocks to engineer self-assembled SmIII-EGCG nanocomplexes with synergistically enhanced tumor inhibitory properties. These nanocomplexes have negligible systemic toxic effects on healthy cells but cause a significant reduction in the viability of melanoma cells by efficiently regulating their metabolic pathways. Moreover, the wound-induced migration of melanoma cells can be efficiently inhibited by SmIII-EGCG, which is a key criterion for metastatic melanoma therapy. In a mouse melanoma tumor model, SmIII-EGCG is directly compared with a clinical anticancer drug, 5-fluorouracil and shows remarkable tumor inhibition. Moreover, the targeted therapy of SmIII-EGCG is shown to prevent metastatic lung melanoma from spreading to main organs with no adverse side effects on the body weight or organs. These in vivo results demonstrate significant advantages of SmIII-EGCG over its clinical counterpart. The results suggest that these green tea-based, self-assembled nanocomplexes possess all of the key traits of a clinically promising candidate to address the challenges associated with the treatment of advanced stage metastatic melanoma.

Metal-dependent inhibition of amyloid fibril formation: synergistic effects of cobalt-tannic acid networks

Metal-phenolic networks (MPNs) have received widespread interest owing to their modular incorporation of functional metal ions and phenolic ligands. However, the interaction between MPNs and biomolecules is still relatively unexplored. Herein, we studied the effects of MPN-coated gold nanoparticles on amyloid fibril formation (which is associated with Alzheimer's disease) as a function of the metal ion in the MPN systems. All coated particles examined inhibited amyloid formation, with cobalt(ii) MPN-coated particles exhibiting the highest inhibition activity (90%). Molecular dynamics simulations and quantum mechanics calculations suggested that the geometry of the exposed cobalt coordination site in the cobalt-tannic acid networks facilitates its interactions with histidine and methionine residues in the amyloid beta peptides. Furthermore, the unique structure of cobalt MPNs may enable a wider variety of biomedical applications.

Facile synthesis of Fe-p-aminophenol nanoparticles for photothermal therapy

Fe-p-aminophenol (Fe-PAP) nanoparticles, a newly developed photothermal agent (PTA), were successfully synthesized via a one-pot method at room temperature.

Self-Assembled Metal-Phenolic Nanoparticles for Enhanced Synergistic Combination Therapy against Colon Cancer

Engineering functional nanomaterials to have both high therapeutic efficacy and minimal side-effects has become a promising strategy for next-generation cancer treatments. Herein, an adenosine triphosphate (ATP) depletion and reactive oxygen species-enhanced combination chemotherapy platform is introduced whereby therapeutic samarium (Sm³⁺ ) ions and (-)-epicatechin (EC) are integrated via a metal-phenolic network (Sm^III -EC). The independent pathway between Sm³⁺ and EC can achieve a synergistic therapeutic effect through the mitochondrial dysfunction process. Sm^III -EC nanoparticles cause a significant reduction of viability of C26 murine colon carcinoma cells while with lower systemic toxic effects on normal cell lines. Sm^III -EC nanoparticles are used to directly compare with a clinic anticancer drug 5-fluorouracil. Sm^III -EC nanoparticles not only decrease the tumor volume but also do not affect the body weight of mice and normal organs, showing significant advantages over clinic counterpart. These facts suggest that Sm^III -EC nanoparticles represent a clinically promising candidate for colon cancer treatment with a targeted therapeutic effect and minimum side toxicity.

Thermal Transition of Bimetallic Metal-Phenolic Networks to Biomass-Derived Hierarchically Porous Nanofibers

The development and utilization of biomass resources could contribute to new materials for long-term sustainable energy storage and environmental applications, reduce environmental impacts, and meet the urgent need for green and sustainable development strategies. Herein, a bimetallic metal-phenolic network (MPN) was applied to incorporate different metallic element species into cattle skin and fabricate collagen-fiber-derived complex oxide nanofibers using natural polyphenols (Myrica tannins). Direct thermal transition of these biomass-MPN composites generates hierarchically porous nanofibers possessing micro- and mesoporous architectures along with a well-preserved macroscopic structure. The pore system and complex oxide composition provide excellent photocatalytic performance. This low-cost, simple, and readily scalable MPN-based approach provides a straightforward route to synthesize nanostructured materials directly from biomass, which could play important roles in a wide range of potential applications.

Novel Metal Polyphenol Framework for MR Imaging-Guided Photothermal Therapy

Phothermal therapy has received increasing attention in recent years as a potentially effective way to treat cancer. In pursuit of a more biocompatible photothermal agent, we utilize biosafe materials including ellagic acid (EA), polyvinylpyrrolidone (PVP), and iron element as building blocks, and we successfully fabricate a homogeneous nanosized Fe-EA framework for the first time by a facile method. As expected, the novel nanoagent exhibits no obvious cytotoxicity and good hemocompatibility in vitro and in vivo. The microenvironment responsiveness to both pH and hydrogen peroxide makes the NPs biodegradable in tumor tissues, and the framework should be easily cleared by the body. Photothermal potentials of the nanoparticles are demonstrated with relevant features of strong NIR light absorption, moderately effective photothermal conversion efficiency, and good photothermal stability. The in vivo photothermal therapy also achieved effective tumor ablation with no apparent toxicity. On the other hand, it also exhibits T2 MR imaging ability originated from ferric ions. Our work highlights the promise of the Fe-EA framework for imaging-guided photothermal therapy.

Europium-phenolic network coated BaGdF5 nanocomposites for tri-modal computed tomography/magnetic resonance/luminescence imaging

Multifunctional nanocomposites based on BaGdF₅ nanoparticles (NPs) and metal phenolic network (MPN) have been engineered as novel contrast agents for potential applications in X-ray computed tomography, magnetic resonance and luminescence imaging. The BaGdF₅@MPN nanocomposites were synthesized at room temperature by coating BaGdF₅ NPs with europium-phenolic network, which was obtained by the coordination of europium (III) with tannic acid (TA). The in vitro cytotoxicity assays against HepG2 cells revealed that the BaGdF₅@MPN nanocomposites presented better cytocompatibility and lower cytotoxity than pure BaGdF₅ NPs. In addition, vivid red and green luminescence can be observed by confocal laser scanning microscope (CLSM) from the BaGdF₅@MPN nanocomposites laden HepG2 cells under the excitation of UV (390 nm) and visible light (440 nm), respectively. The longitudinal relaxivity value (r₁) of the nanocomposites was 2.457 mM^-1s^-1. Moreover, the nanocomoposites exhibited X-ray computed tomography (CT) and T₁-weighted magnetic resonance (MR) imaging capacities, and the intensities of the enhanced signals of in vitro CT and MR images were proportional to the concentrations of the nanocomposites. These results indicated that the as-prepared BaGdF₅@MPN nanocomposites are promising contrast agents for CT/MR/luminescence imaging.

Ultrasound Detection of Regional Oxidative Stress in Deep Tissues Using Novel Enzyme Loaded Nanoparticles

Oxidative stress is a powerful tool that is critical to immune mediated responses in healthy individuals, yet additionally plays a crucial role in development of cancer, inflammatory pathologies, and tissue ischemia. Despite this, there remain relatively few molecular tools to study oxidative stress, particularly in living mammals. To develop an intravenously injectable probe capable of labeling sites of oxidative stress in vivo, 200 nm catalase synthetic hollow enzyme loaded nanospheres (catSHELS) are designed and fabricated using a versatile enzyme nanoencapsulation method. catSHELS catalyze H₂ O₂ to water and oxygen producing microbubbles that can be detected and imaged using a clinical ultrasound system. catSHELS are optimized in vitro to maximize ultrasound signal and their functionality is demonstrated in rat ischemic renal injury model. Ischemic oxidative injury is induced in a single kidney of normal rats by clamping the renal artery for 1 h followed by 2 h of reperfusion. Imaging of both kidneys is performed following the intravenous bolus injection of 10¹² catSHELS of the optimized formulation. There is significant increase in ultrasound signal of the injured kidney relative to controls. This method offers a novel intravenous approach to detect oxidative stress in deep tissues in living animals.

pH-Responsive nanodrug encapsulated by tannic acid complex for controlled drug delivery

Metal ions/polyphenol complexes encapsulated paclitaxel nanodrug with high pH-sensitive drug release property and enhanced antitumor activity was obtained.

Innovation in Layer-by-Layer Assembly

Methods for depositing thin films are important in generating functional materials for diverse applications in a wide variety of fields. Over the last half-century, the layer-by-layer assembly of nanoscale films has received intense and growing interest. This has been fueled by innovation in the available materials and assembly technologies, as well as the film-characterization techniques. In this Review, we explore, discuss, and detail innovation in layer-by-layer assembly in terms of past and present developments, and we highlight how these might guide future advances. A particular focus is on conventional and early developments that have only recently regained interest in the layer-by-layer assembly field. We then review unconventional assemblies and approaches that have been gaining popularity, which include inorganic/organic hybrid materials, cells and tissues, and the use of stereocomplexation, patterning, and dip-pen lithography, to name a few. A relatively recent development is the use of layer-by-layer assembly materials and techniques to assemble films in a single continuous step. We name this "quasi"-layer-by-layer assembly and discuss the impacts and innovations surrounding this approach. Finally, the application of characterization methods to monitor and evaluate layer-by-layer assembly is discussed, as innovation in this area is often overlooked but is essential for development of the field. While we intend for this Review to be easily accessible and act as a guide to researchers new to layer-by-layer assembly, we also believe it will provide insight to current researchers in the field and help guide future developments and innovation.