Functional Macromolecule-Enabled Colloidal Synthesis: From Nanoparticle Engineering to Multifunctionality

Multimodal Golden DNA Superstructures (GDSs) for Highly Efficient Photothermal Immunotherapy

DNA-templated metallization has emerged as an efficient strategy for creating nanoscale-metal DNA hybrid structures with a desirable conformation and function. Despite the potential of DNA-metal hybrids, their use as combinatory therapeutic agents has rarely been examined. Herein, we present a simple approach for fabricating a multipurpose DNA superstructure that serves as an efficient photoimmunotherapy agent. Specifically, we adsorb and locally concentrate Au ions onto DNA superstructures through induced local reduction, resulting in the formation of Au nanoclusters. The mechanical and optical properties of these metallic nanoclusters can be rationally controlled by their conformations and metal ions. The resulting golden DNA superstructures (GDSs) exhibit significant photothermal effects that induce cancer cell apoptosis. When sequence-specific immunostimulatory effects of DNA are combined, GDSs provide a synergistic effect to eradicate cancer and inhibit metastasis, demonstrating potential as a combinatory therapeutic agent for tumor treatment. Altogether, the DNA superstructure-templated metal casting system offers promising materials for future biomedical applications.

Recent Advances of Seed-Mediated Growth of Metal Nanoparticles: from Growth to Applications

Unprecedented advances in metal nanoparticle synthesis have paved the way for broad applications in sensing, imaging, catalysis, diagnosis, and therapy by tuning the optical properties, enhancing catalytic performance, and improving chemical and biological properties of metal nanoparticles. The central guiding concept for regulating the size and morphology of metal nanoparticles is identified as the precise manipulation of nucleation and subsequent growth, often known as seed-mediated growth methods. However, since the growth process is sensitive not only to the metal seeds but also to capping agents, metal precursors, growth solution, growth/incubation time, reductants, and other influencing factors, the precise control of metal nanoparticle morphology is multifactorial. Further, multiple reaction parameters are entangled with each other, so it is necessary to clarify the mechanism by which each factor precisely regulates the morphology of metal nanoparticles. In this review, to exploit the generality and extendibility of metal nanoparticle synthesis, the mechanisms of growth influencing factors in seed-mediated growth methods are systematically summarized. Second, a variety of critical properties and applications enabled by grown metal nanoparticles are focused upon. Finally, the current progress and offer insights on the challenges, opportunities, and future directions for the growth and applications of grown metal nanoparticles are reviewed.

Supramolecular Polyphenol-DNA Microparticles for In Vivo Adjuvant and Antigen Co-Delivery and Immune Stimulation

DNA-based materials have attracted interest due to the tunable structure and encoded biological functionality of nucleic acids. A simple and general approach to synthesize DNA-based materials with fine control over morphology and bioactivity is important to expand their applications. Here, we report the synthesis of DNA-based particles via the supramolecular assembly of tannic acid (TA) and DNA. Uniform particles with different morphologies are obtained using a variety of DNA building blocks. The particles enable the co-delivery of cytosine-guanine adjuvant sequences and the antigen ovalbumin in model cells. Intramuscular injection of the particles in mice induces antigen-specific antibody production and T cell responses with no apparent toxicity. Protein expression in cells is shown using capsules assembled from TA and plasmid DNA. This work highlights the potential of TA as a universal material for directing the supramolecular assembly of DNA into gene and vaccine delivery platforms.

Polydopamine-Based Nanoparticles for an Antibiofilm Platform: Influence of Size and Surface Charge on Their Penetration and Accumulation in S. aureus Biofilms

Various functional polydopamine (PDA) nanoparticles have been developed to treat biofilms in recent years; however, in-depth knowledge of how the physicochemical properties of the nanoparticles impact their penetration and accumulation in biofilms is lacking. In this work, PDA nanoparticles of 15, 60, 90, and 200 nm sizes were synthesized and carboxyl, methoxy, and amine groups were introduced to the particle surface to control their surface charges, and then the penetration and accumulation of these PDA nanoparticles in S. aureus biofilms were investigated. The PDA nanoparticles of approximately 60 nm size (PDA60) showed higher penetration and accumulation abilities than nanoparticles of other sizes, and the positively charged amine groups introduced onto the surfaces of PDA60 nanoparticles were more effective than carboxyl or methoxy groups in promoting the interactions of the nanoparticles with the biofilm. The PDA60 nanoparticles with amine surface groups exhibited good photothermal properties, and confocal laser scanning microscopy revealed that they were able to accumulate in the biofilm in significant amounts, which upon irradiation with a laser of 808 nm wavelength showed a high bactericidal rate (97.1%) against the biofilm. The findings of this work provide guidance for the design and development of nanoparticles for antibiofilm application.

Caging Cationic Polymer Brush-Coated Plasmonic Nanostructures for Traceable Selective Antimicrobial Activities

Cationic polymers are under intense research to achieve prominent antimicrobial activity. However, the cellular and in vivo toxicity caused by nonspecific electrostatic interaction has become a major challenge for their practical applications. Here, the development of a "caging" strategy based on the use of a block copolymer consisting of a stealth block and an anionic block that undergoes degradation in presence of enzymes secreted by selective bacterial pathogens of interest is reported. The results have shown that antimicrobial cationic polymer brushes-coated gold nanorods (AuNRs) can be caged by the block polymer of poly(ethylene glycol) and anionic, lipase-degradable block of ε-caprolactone and methacrylic acid copolymer to afford neutrally charged surfaces. The caged AuNRs are activated by lipase released by bacteria of interest to endow an excellent bactericidal effect but show minimal binding and toxicity against mammalian cells and nonspecific bacteria that do not produce lipase. In this design, AuNRs play multifunctional roles as the scaffolds for polymer brushes, photothermal transducers, and imaging probes for traceable delivery of the activation and delivery of bactericidal cationic polymer brushes. The caging strategy opens new opportunities for the safe delivery of antimicrobial materials for the treatment of bacterial infections.

Colloidal Self-Assembly Approaches to Smart Nanostructured Materials

Colloidal self-assembly refers to a solution-processed assembly of nanometer-/micrometer-sized, well-dispersed particles into secondary structures, whose collective properties are controlled by not only nanoparticle property but also the superstructure symmetry, orientation, phase, and dimension. This combination of characteristics makes colloidal superstructures highly susceptible to remote stimuli or local environmental changes, representing a prominent platform for developing stimuli-responsive materials and smart devices. Chemists are achieving even more delicate control over their active responses to various practical stimuli, setting the stage ready for fully exploiting the potential of this unique set of materials. This review addresses the assembly of colloids into stimuli-responsive or smart nanostructured materials. We first delineate the colloidal self-assembly driven by forces of different length scales. A set of concepts and equations are outlined for controlling the colloidal crystal growth, appreciating the importance of particle connectivity in creating responsive superstructures. We then present working mechanisms and practical strategies for engineering smart colloidal assemblies. The concepts underpinning separation and connectivity control are systematically introduced, allowing active tuning and precise prediction of the colloidal crystal properties in response to external stimuli. Various exciting applications of these unique materials are summarized with a specific focus on the structure-property correlation in smart materials and functional devices. We conclude this review with a summary of existing challenges in colloidal self-assembly of smart materials and provide a perspective on their further advances to the next generation.

Intercluster Exchange-Stabilized Novel Complex Colloidal χc Phase

Designing complex cluster crystals with a specific function using simple colloidal building blocks remains a challenge in materials science. Herein, we propose a conceptually new design strategy for constructing complex cluster crystals via hierarchical self-assembly of simple soft Janus colloids. A novel and previously unreported colloidal cluster-χ (χ_c) phase, which resembles the essential structural features of α-manganese but at a larger length scale, is obtained through molecular dynamics simulations. The formation of the χ_c phase undergoes a remarkable two-step self-assembly process, that is, the self-assembly of clusters with specific size dispersity from Janus colloids, followed by the highly ordered organization of these clusters. More importantly, the dynamic exchange of particles between these clusters plays a critical role in stabilizing the χ_c phase. Such a conceptual design framework based on intercluster exchange has the potential to effectively construct novel complex cluster crystals by hierarchical self-assembly of colloidal building blocks.

Robust and Versatile Coatings Engineered via Simultaneous Covalent and Noncovalent Interactions

Interfacial modular assembly has emerged as an adaptable strategy for engineering the surface properties of substrates in biomedicine, photonics, and catalysis. Herein, we report a versatile and robust coating (pBDT-TA), self-assembled from tannic acid (TA) and a self-polymerizing aromatic dithiol (i.e., benzene-1,4-dithiol, BDT), that can be engineered on diverse substrates with a precisely tuned thickness (5-40 nm) by varying the concentration of BDT used. The pBDT-TA coating is stabilized by covalent (disulfide) bonds and supramolecular (π-π) interactions, endowing the coating with high stability in various harsh aqueous environments across ionic strength, pH, temperature (e.g., 100 mM NaCl, HCl (pH 1) or NaOH (pH 13), and water at 100 °C), as well as surfactant solution (e.g., 100 mM Triton X-100) and biological buffer (e.g., Dulbecco's phosphate-buffered saline), as validated by experiments and simulations. Moreover, the reported pBDT-TA coating enables secondary reactions on the coating for engineering hybrid adlayers (e.g., ZIF-8 shells) via phenolic-mediated adhesion, and the facile integration of aromatic fluorescent dyes (e.g., rhodamine B) via π interactions without requiring elaborate synthetic processes.

SPECT imaging and highly efficient therapy of rheumatoid arthritis based on hyperbranched semiconducting polymer nanoparticles

Rheumatoid arthritis (RA) is an inflammatory autoimmune disease. Although significant progress has been made in clinical treatment, joint inflammation may continue or worsen, and may even progress to the end-stage that requires joint replacement. Traditional therapy using methotrexate (MTX) would cause serious off-target systemic toxicities. Therefore, it is crucial to effectively and specifically deliver MTX to targeted inflamed joints to decrease its adverse systemic toxicities and improve its therapeutic index. Herein, we develop multifunctional nanocarriers for diagnostic radioisotope (99mTc) labeling and therapeutic targeted drug (MTX) delivery by using PEGylated hyperbranched semiconducting polymer nanoparticles (HSP-PEG-NPs) as carriers. Upon intravenous administration, the nanoparticles can extravasate through the turbulent blood-joint barrier and access the inflamed joints. In vivo SPECT/CT imaging shows high accumulation in the inflamed joints of mice with RA after intravenous injection of HSP-PEG-NPs with 99mTc labeling (99mTc-HSP-PEG). In vivo therapeutic evaluations suggest that MTX@HSP-PEG-NPs significantly alleviate RA with a high therapeutic index and relatively low adverse systemic toxicities in comparison with free MTX at the same dose. Our study shows that HSP-PEG-NPs could serve as multifunctional vehicles to deliver radioisotopes for in vivo imaging, and MTX for RA treatment, highlighting the innovative development of the nanoparticle-based RA treatment strategy for clinical applications.

Synthesis of V-notched half-open polymer microspheres via facile solvent-tuned self-assembly

Polymer microspheres with a special V-notched half-open architecture were synthesized in a mixed solvent of water/ethanol (1 : 1 v/v) at room temperature.

Particle engineering enabled by polyphenol-mediated supramolecular networks

We report a facile strategy for engineering diverse particles based on the supramolecular assembly of natural polyphenols and a self-polymerizable aromatic dithiol. In aqueous conditions, uniform and size-tunable supramolecular particles are assembled through π–π interactions as mediated by polyphenols. Owing to the high binding affinity of phenolic motifs present at the surface, these particles allow for the subsequent deposition of various materials (i.e., organic, inorganic, and hybrid components), producing a variety of monodisperse functional particles. Moreover, the solvent-dependent disassembly of the supramolecular networks enables their removal, generating a wide range of corresponding hollow structures including capsules and yolk–shell structures. The versatility of these supramolecular networks, combined with their negligible cytotoxicity provides a pathway for the rational design of a range of particle systems (including core–shell, hollow, and yolk–shell) with potential in biomedical and environmental applications.

Monodisperse colloidal particles with tunable properties show promise for biomedical, energy, and environmental applications and simple routes for fabricating these particles are of interest. Here, the authors report a facile strategy for fabrication of diverse particles based on the supramolecular assembly of phenols and self-polymerizable thiols

Prevention of Hepatic Ischemia-Reperfusion Injury by Carbohydrate-Derived Nanoantioxidants

Hepatic ischemia-reperfusion injury (IRI), which mainly results from excessive reactive oxygen species (ROS) generated by a reperfusion burst of oxygen, has long been a major cause of liver dysfunction and failure after surgical procedures. Here, a monodispersed hydrophilic carbohydrate-derived nanoparticle (C-NP) was synthesized as a nanoantioxidant that could effectively prevent hepatic IRI. The spherical C-NPs had a size of ∼78 ± 11.3 nm covered with polar surface groups. They were well dispersible in water with good colloidal stability, nontoxicity, and good ROS scavenging capability. The C-NPs also exhibited good circulation lifetime, effective delivery to liver, and gradual degradability with an ability to assist the IRI group maintaining a normal and healthy liver status. The pathology mechanism of C-NPs in hepatic IRI was confirmed to be scavenging of excessive ROS by C-NPs. The effective therapeutic treatment of C-NPs in living animals revealed a great potential in clinical prevention for hepatic IRI.

Chiral Active β-Glucan Nanoparticles for Synergistic Delivery of Doxorubicin and Immune Potentiation

Background

β-glucans are chiral polysaccharides with well-defined immunological properties and supramolecular wrapping ability of its chiral feature. However, the exploitation of chiral properties of these nanoparticles in drug delivery systems was seldom conducted.

Methods

β-glucan molecules with different chain lengths were extracted from yeast Saccharomyces cerevisiae and thereafter modified. In a conformation transition process, these β-glucan molecules were then self-assembled with anti-cancer drug doxorubicin into nanoparticles to construct drug delivery systems. The chiral interactions between the drug and carriers were revealed by circular dichroism spectra, ultraviolet and visible spectrum, fourier transform infrared spectroscopy, dynamic light scattering and transmission electron microscope. The immune-potentiation properties of modified β-glucan nanoparticles were evaluated by analysis of the mRNA expression in RAW264.7 cell model. Further, the antitumor efficacy of the nanoparticles against the human breast cancer were studied in MCF-7 cell model by cellular uptake and cytotoxicity experiments.

Results

β-glucan nanoparticles can activate macrophages to produce immune enhancing cytokines (IL-1β, IL-6, TNF-α, IFN-γ). A special chirality of the carriers in diameter of 50~160 nm can also associate with higher drug loading ability of 13.9% ~38.2% and pH-sensitive release with a change of pH from 7.4 to 5.0. Cellular uptake and cytotoxicity experiments also prove that the chiral-active β-glucan nanoparticles can be used in anti-cancer nanomedicine.

Conclusion

This work demonstrates that β-glucans nanoparticles with special chiral feature which leading to strong immunopotentiation ability and high drug loading efficiency can be developed as a novel type of nanomedicine for anti-cancer treatment.

An Insight into the Structural Diversity and Clinical Applicability of Polyurethanes in Biomedicine

Due to their mechanical properties, ranging from flexible to hard materials, polyurethanes (PUs) have been widely used in many industrial and biomedical applications. PUs’ characteristics, along with their biocompatibility, make them successful biomaterials for short and medium-duration applications. The morphology of PUs includes two structural phases: hard and soft segments. Their high mechanical resistance featuresare determined by the hard segment, while the elastomeric behaviour is established by the soft segment. The most important biomedical applications of PUs include antibacterial surfaces and catheters, blood oxygenators, dialysis devices, stents, cardiac valves, vascular prostheses, bioadhesives/surgical dressings/pressure-sensitive adhesives, drug delivery systems, tissue engineering scaffolds and electrospinning, nerve generation, pacemaker lead insulation and coatings for breast implants. The diversity of polyurethane properties, due to the ease of bulk and surface modification, plays a vital role in their applications.

Alginate mediated functional aggregation of gold nanoclusters for systemic photothermal therapy and efficient renal clearance

For renal clearable nanoagents, it is challenging to delay the renal clearance to acquire efficient tumor accumulation. Herein, we report sodium alginate (SA) stabilized gold (Au) NCs. The Au NCs are of high biocompatibility and renal clearable. Contributed from the ligands of SA, the half-life (t_1/2) of Au NCs is prolonged to ∼9.3 h, enhancing the tumor accumulation rate to 10.4 %ID/g. In tumor microenvironment (TME), the Au NCs are stimulated to functionally aggregate, which switches on the photothermal effect. Animal experiments prove that Au NCs aggregates are efficient photothermal therapy (PTT) agents for both local treatment of single tumors and systemic treatment of double-tumor models without causing noticeable side effects, confirming the biosecurity of Au NCs and systemic PTT. The switchable strategy of PTT may signify the establishment of a new systemic therapeutic methodology.

A novel method for in situ visualization of the growth kinetics, structures and behaviours of gas-phase fabricated metallic alloy nanoparticles

Modulation of gas-phase nanoparticles is unmethodical as there is a lack of information on the growth kinetics and its determinants. Here, we developed a novel in situ evaporation-and-deposition (EAD) method inside a transmission electron microscope which enables direct visualization of the nucleation, growth, coalescence and shape/phase evolution of gas-phase fabricated nanoparticles. Using a Bi₄₉Pb₁₈Sn₁₂In₂₁ alloy as a sample, the critical factors that determine the feasibility of this EAD method are revealed. By direct observation, it is unambiguously evidenced that pristine nanoparticles with ultra-clean surfaces are extremely energetic during growth. Coalescence between EAD-fabricated nanoparticles takes place in a manner beyond conventional understanding acquired by postmortem analyses. Moreover, the EAD-fabricated diverse nanoparticles show distinct size distributions and sandwich-type or Janus-type phase segregations. These features offer an effective tool to identify atomic surface steps of thin films and can provide an ideal case for exploring the phase diagrams of nanoalloys in the future.

In situ visualizing the growth kinetics and behaviours of alloy nanoparticles by a novel EAD method.

Nanoengineering multifunctional hybrid interfaces using adhesive glycogen nanoparticles

Amphiphilic phytoglycogen nanoparticles are used as building blocks for engineering multifunctional hybrid films with catalytic and sensing properties.