Biomimetic Nanosilica–Collagen Scaffolds for In Situ Bone Regeneration: Toward a Cell‐Free,One‐Step Surgery

Current approaches to fabrication of nSC composites for bone tissue engineering (BTE) have limited capacity to achieve uniform surface functionalization while replicating the complex architecture and bioactivity of native bone, compromising application of these nanocomposites for in situ bone regeneration. A robust biosilicification strategy is reported to impart a uniform and stable osteoinductive surface to porous collagen scaffolds. The resultant nSC composites possess a native‐bone‐like porous structure and a nanosilica coating. The osteoinductivity of the nSC scaffolds is strongly dependent on the surface roughness and silicon content in the silica coating. Notably, without the use of exogenous cells and growth factors (GFs), the nSC scaffolds induce successful repair of a critical‐sized calvarium defect in a rabbit model. It is revealed that topographic and chemical cues presented by nSC scaffolds could synergistically activate multiple signaling pathways related to mesenchymal stem cell recruitment and bone regeneration. Thus, this facile surface biosilicification approach could be valuable by enabling production of BTE scaffolds with large sizes, complex porous structures, and varied osteoinductivity. The nanosilica‐functionalized scaffolds can be implanted via a cell/GF‐free, one‐step surgery for in situ bone regeneration, thus demonstrating high potential for clinical translation in treatment of massive bone defects.     

Nitric Oxide Releasing Coronary Stent: A New Approach Using Layer‐by‐Layer Coating and Liposomal Encapsulation

The sustained or controlled release of nitric oxide (NO) can be the most promising approach for the suppression or prevention of restenosis and thrombosis caused by stent implantation. The aim of this study is to investigate the feasibility in the potential use of layer‐by‐layer (LBL) coating with a NO donor‐containing liposomes to control the release rate of NO from a metallic stent. Microscopic observation and surface characterizations of LBL‐modified stents demonstrate successful LBL coating with liposomes on a stent. Release profiles of NO show that the release rate is sustained up to 5 d. In vitro cell study demonstrates that NO release significantly enhances endothelial cell proliferation, whereas it markedly inhibits smooth muscle cell proliferation. Finally, in vivo study conducted with a porcine coronary injury model proves the therapeutic efficacy of the NO‐releasing stents coated by liposomal LBL technique, supported by improved results in luminal healing, inflammation, and neointimal thickening except thrombo‐resistant effect. As a result, all these results demonstrate that highly optimized release rate and therapeutic dose of NO can be achieved by LBL coating and liposomal encapsulation, followed by significantly efficacious outcome in vivo.     

Layer‐by‐Layer Assembled Oxide Nanoparticle Electrodes with High Transparency,Electrical Conductivity,and Electrochemical Activity by Reducing Organic Linker‐Induced Oxygen Vacancies

Solution‐processable transparent conducting oxide (TCO) nanoparticle (NP)–based electrodes are limited by their low electrical conductivity, which originates from the low level of oxygen vacancies within NPs and the contact resistance between neighboring NPs. Additionally, these electrodes suffer from the troublesome trade‐off between electrical conductivity and optical transmittance and the restricted shape of substrates (i.e., only flat substrates). An oxygen‐vacancy‐controlled indium tin oxide (ITO) NP‐based electrode is introduced using carbon‐free molecular linkers with strong chemically reducing properties. Specifically, ITO NPs are layer‐by‐layer assembled with extremely small hydrazine monohydrate linkers composed of two amine groups, followed by thermal annealing. This approach markedly improves the electrical conductivity of ITO NP‐based electrodes by significantly increasing the level of oxygen vacancies and decreasing the interparticle distance (i.e., contact resistance) without sacrificing optical transmittance. The prepared electrodes surpass the optical/electrical performance of TCO NP‐based electrodes reported to date. Additionally, the nanostructured ITO NP films can be applied to more complex geometric substrates beyond flat substrates, and furthermore exhibit a prominent electrochemical activity. This approach can provide an important basis for developing a wide range of highly functional transparent conducting electrodes.     

Rapid and Low‐Cost Prototyping of 3D Nanostructures with Multi‐Layer Hydrogen Silsesquioxane Scaffolds

A layer‐by‐layer (LBL) method can generate or approximate any three‐dimensional (3D) structure, and has been the approach for the manufacturing of complementary metal‐oxide‐semiconductor (CMOS) devices. However, its high cost precludes the fabrication of anything other than CMOS‐compatible devices, and general 3D nanostructures have been difficult to prototype in academia and small businesses, due to the lack of expensive facility and state‐of‐the‐art tools. It is proposed and demonstrated that a novel process that can rapidly fabricate high‐resolution three‐dimensional (3D) nanostructures at low cost, without requiring specialized equipment. An individual layer is realized through electron‐beam lithography patterning of hydrogen silsesquioxane (HSQ) resist, followed by planarization via spinning SU‐8 resist and etch‐back. A 4‐layer silicon inverse woodpile photonic crystal with a period of 650 nm and a 7‐layer HSQ scaffold with a period of 300 nm are demonstrated. This process provides a versatile and accessible solution to the fabrication of highly complex 3D nanostructures.     

Mitochondria‐Targeted Polydopamine Nanocomposite with AIE Photosensitizer for Image‐Guided Photodynamic and Photothermal Tumor Ablation

Photodynamic therapy (PDT) and photothermal therapy (PTT) are two kinds of treatment for tumors. Herein, a new aggregation‐induced emission (AIE)gen (MeO‐TPE‐indo, MTi) is synthesized with a D–π–A conjugated structure. MTi, which has an electron donor and an acceptor on a tetraphenylethene (TPE) conjugated skeleton, can induce the effective generation of reactive oxygen species (ROS) for PDT. With the guide of the indolium group, MTi can target and image mitochondrion selectively. In order to get good dispersion in water and long‐time retention in tumors, MTi is modified on the surface of polydopamine nanoparticles (PDA NPs) to form the nanocomposite (PDA‐MeO‐TPE‐indo, PMTi ) by π–π and hydrogen interactions. PMTi is a nanoscale composite for imaging‐guided PDT and PTT in tumor treatment, which is constructed with AIEgens and PDA for the first time. The organic functional molecules are combined with nanomaterials for building a multifunctional diagnosis and treatment platform by utilizing the advantages of both sides.     

Toward Efficient Polymer Solar Cells Processed by a Solution‐Processed Layer‐By‐Layer Approach

The solution‐processed layer‐by‐layer (LBL) method has potential to achieve high‐performance polymer solar cells (PSCs) due to its advantage of enriching donors near the anode and acceptors near the cathode. However, power conversion efficiencies (PCEs) of the LBL‐PSCs are still significantly lower than those of conventional one‐step‐processed PSCs (OS‐PSCs). A method to solve the critical problems in LBL‐PSCs is reported here. By employing a specific mixed solvent (o‐dichlorobenzene [o‐DCB]/tetrahydrofuran) to spin‐coat the small‐molecular acceptor IT‐4F onto a layer of the newly designed polymer donor (PBDB‐TFS1), appropriate interdiffusion between the PBDB‐TFS1 and the IT‐4F can critically be controlled, and then an ideal phase separation of the active layer and large donor/acceptor interface area can be realized with a certain amount of o‐DCB. The PSCs based on the LBL method exhibit PCEs as high as 13.0%, higher than that of the counterpart (11.8%) made by the conventional OS solution method. This preliminary work reveals that the LBL method is a promising approach to the promotion of the photovoltaic performance of polymer solar cells.     

Dual pH/ROS‐Responsive Nanoplatform with Deep Tumor Penetration and Self‐Amplified Drug Release for Enhancing Tumor Chemotherapeutic Efficacy

Poor deep tumor penetration and incomplete intracellular drug release remain challenges for antitumor nanomedicine application in clinical settings. Herein, a nanomedicine (RLPA‐NPs) is developed that can achieve prolonged blood circulation, deep tumor penetration, active‐targeting of cancer cells, endosome/lysosome escape, and intracellular selectivity self‐amplified drug release for effective drug delivery. The RLPA‐NPs are constructed by encapsulation of a pH‐sensitive polymer octadecylamine‐poly(aspartate‐1‐(3‐aminopropyl) imidazole) (OA‐P(Asp‐API)) and a ROS‐generation agent, β‐Lapachone (Lap), in micelles assembled by the tumor‐penetration peptide internalizing RGD (iRGD)‐modified ROS‐responsive paclitaxel (PTX)‐prodrug. iRGD could promote RLPA‐NPs penetration into deep tumor tissue, and specific targeting to cancer cells. After internalization by cancer cells through receptor‐mediated endocytosis, OA‐P(Asp‐API) can rapidly protonate in the endosome's acidic environment, resulting in RLPA‐NPs escape from the endosome through the “proton sponge effect”. At the same time, the RLPA‐NPs micelle disassembles, releasing Lap and PTX‐prodrug. Subsequently, the released Lap could generate ROS, consequently amplifying and accelerating PTX release to kill tumor cells. The in vitro and in vivo studies demonstrated that RLPA‐NPs can significantly improve the therapeutic effect compared to control groups. Therefore, RLPA‐NPs are a promising nanoplatform for overcoming multiple physiological and pathological barriers to enhance drug delivery.     

The Light‐Induced Field‐Effect Solar Cell Concept – Perovskite Nanoparticle Coating Introduces Polarization Enhancing Silicon Cell Efficiency

Solar cell generates electrical energy from light one via pulling excited carrier away under built‐in asymmetry. Doped semiconductor with antireflection layer is general strategy to achieve this including crystalline silicon (c‐Si) solar cell. However, loss of extra energy beyond band gap and light reflection in particular wavelength range is known to hinder the efficiency of c‐Si cell. Here, it is found that part of short wavelength sunlight can be converted into polarization electrical field, which strengthens asymmetry in organic‐c‐Si heterojunction solar cell through molecule alignment process. The light harvested by organometal trihalide perovskite nanoparticles (NPs) induces molecular alignment on a conducting polymer, which generates positive electrical surface field. Furthermore, a “field‐effect solar cell” is successfully developed and implemented by combining perovskite NPs with organic/c‐Si heterojunction associating with light‐induced molecule alignment, which achieves an efficiency of 14.3%. In comparison, the device with the analogous structure without perovskite NPs only exhibits an efficiency of 12.7%. This finding provides a novel concept to design solar cell by sacrificing part of sunlight to provide “extra” asymmetrical field continuously as to drive photogenerated carrier toward respective contacts under direct sunlight. Moreover, it also points out a method to combine promising perovskite material with c‐Si solar cell.     

Ceria Nanoparticles Meet Hepatic Ischemia‐Reperfusion Injury: The Perfect Imperfection

The mononuclear phagocyte system (MPS, e.g., liver, spleen) is often treated as a “blackbox” by nanoresearchers in translating nanomedicines. Often, most of the injected nanomaterials are sequestered by the MPS, preventing their delivery to the desired disease areas. Here, this imperfection is exploited by applying nano‐antioxidants with preferential liver uptake to directly prevent hepatic ischemia‐reperfusion injury (IRI), which is a reactive oxygen species (ROS)‐related disease. Ceria nanoparticles (NPs) are selected as a representative nano‐antioxidant and the detailed mechanism of preventing IRI is investigated. It is found that ceria NPs effectively alleviate the clinical symptoms of hepatic IRI by scavenging ROS, inhibiting activation of Kupffer cells and monocyte/macrophage cells. The released pro‐inflammatory cytokines are then significantly reduced and the recruitment and infiltration of neutrophils are minimized, which suppress subsequent inflammatory reaction involved in the liver. The protective effect of nano‐antioxidants against hepatic IRI in living animals and the revealed mechanism herein suggests their future use for the treatment of hepatic IRI in the clinic.     

A Sequential Target‐Responsive Nanocarrier with Enhanced Tumor Penetration and Neighboring Effect In Vivo

Nanodrug‐based cancer therapy is impeded by poor penetration into deep tumor tissues mainly due to the overexpression of hyaluronic acid (HA) in the tumor extracellular matrix (ECM). Although modification of nanoparticles (NPs) with hyaluronidase (HAase) is a potent strategy, it remains challenging to get a uniform distribution of drug at the tumor site because of the internalization of NPs by the cells in the tumor and HA regeneration. Herein, an intelligent nanocarrier, which can release HAase in response to the acidic tumor microenvironment (pH 6.5) and perform a strong neighboring effect with size reduction to overcome the above two problems and accomplish drug deep tumor penetration in vivo, is reported. In this design, HAase is encapsulated on the surfaces of doxorubicin (DOX) preloaded ZnO‐DOX NPs using a charge convertible polymer PEG‐PAH‐DMMA (ZDHD). The polymer can release HAase to degrade HA in the tumor ECM (pH 6.5). ZnO‐DOX NPs can release DOX in lysosomes (pH 4.5) to induce cell apoptosis, and exert a neighboring effect with size reduction to infect neighboring cells. The hierarchical targeted release of HAase and drugs is demonstrated to enhance tumor penetration and decrease side effects in vivo. This work shows promise for further application of ZDHD NPs in cancer therapy.     

pH‐Sensitive Polymeric Nanoparticles Modulate Autophagic Effect via Lysosome Impairment

In drug delivery systems, pH‐sensitive polymers are commonly used as drug carriers, and significant efforts have been devoted to the aspects of controlled delivery and release of drugs. However, few studies address the possible autophagic effects on cells. Here, for the first time, using a fluorescent autophagy‐reporting cell line, this study evaluates the autophagy‐induced capabilities of four types of pH‐sensitive polymeric nanoparticles (NPs) with different physical properties, including size, surface modification, and pH‐sensitivity. Based on experimental results, this study concludes that pH‐sensitivity is one of the most important factors in autophagy induction. In addition, this study finds that variation of concentration of NPs could cause different autophagic effect, i.e., low concentration of NPs induces autophagy in an mTOR‐dependent manner, but high dose of NPs leads to autophagic cell death. Identification of this tunable autophagic effect offers a novel strategy for enhancing therapeutic effect in cancer therapy through modulation of autophagy.     

Solvent‐Induced Self‐Assembly Strategy to Synthesize Well‐Defined Hierarchically Porous Polymers

Porous polymers with well‐orchestrated nanomorphologies are useful in many fields, but high surface area, hierarchical structure, and ordered pores are difficult to be satisfied in one polymer simultaneously. Herein, a solvent‐induced self‐assembly strategy to synthesize hierarchical porous polymers with tunable morphology, mesoporous structure, and microporous pore wall is reported. The poly(ethylene oxide)‐b‐polystyrene (PEO‐b‐PS) diblock copolymer micelles are cross‐linked via Friedel–Crafts reaction, which is a new way to anchor micelles into porous polymers with well‐defined structure. Varying the polarity of the solvent has a dramatic effect upon the oleophobic/oleophylic interaction, and the self‐assembly structure of PEO‐b‐PS can be tailored from aggregated nanoparticles to hollow spheres even mesoporous bulk. A morphological phase diagram is accomplished to systematically evaluate the influence of the composition of PEO‐b‐PS and the mixed solvent component on the pore structure and morphology of products. The hypercrosslinked hollow polymer spheres provide a confined microenvironment for the in situ reduction of K₂PdCl₄ to ultrasmall Pd nanoparticles, which exhibit excellent catalytic performance in solvent‐free catalytic oxidation of hydrocarbons and alcohols.     

A Polymer Encapsulation Strategy to Synthesize Porous Nitrogen‐Doped Carbon‐Nanosphere‐Supported Metal Isolated‐Single‐Atomic‐Site Catalysts

A novel polymer encapsulation strategy to synthesize metal isolated‐single‐atomic‐site (ISAS) catalysts supported by porous nitrogen‐doped carbon nanospheres is reported. First, metal precursors are encapsulated in situ by polymers through polymerization; then, metal ISASs are created within the polymer‐derived p‐CN nanospheres by controlled pyrolysis at high temperature (200–900 °C). Transmission electron microscopy and N₂ sorption results reveal this material to exhibit a nanospheric morphology, a high surface area (≈380 m² g^?1), and a porous structure (with micropores and mesopores). Characterization by aberration‐corrected high‐angle annular dark‐field scanning transmission electron microscopy and X‐ray absorption fine structure confirms the metal to be present as metal ISASs. This methodology is applicable to both noble and nonprecious metals (M‐ISAS/p‐CN, M = Co, Ni, Cu, Mn, Pd, etc.). In particular, the Co‐ISAS/p‐CN nanospheres obtained using this method show comparable (E_1/2 = 0.838 V) electrochemical oxygen reduction activity to commercial Pt/C with 20 wt% Pt loading (E_1/2 = 0.834 V) in alkaline media, superior methanol tolerance, and outstanding stability, even after 5000 cycles.     

A Layer‐by‐Layer ZnO Nanoparticle–PbS Quantum Dot Self‐Assembly Platform for Ultrafast Interfacial Electron Injection

Absorbent layers of semiconductor quantum dots (QDs) are now used as material platforms for low‐cost, high‐performance solar cells. The semiconductor metal oxide nanoparticles as an acceptor layer have become an integral part of the next generation solar cell. To achieve sufficient electron transfer and subsequently high conversion efficiency in these solar cells, however, energy‐level alignment and interfacial contact between the donor and the acceptor units are needed. Here, the layer‐by‐layer (LbL) technique is used to assemble ZnO nanoparticles (NPs), providing adequate PbS QD uptake to achieve greater interfacial contact compared with traditional sputtering methods. Electron injection at the PbS QD and ZnO NP interface is investigated using broadband transient absorption spectroscopy with 120 femtosecond temporal resolution. The results indicate that electron injection from photoexcited PbS QDs to ZnO NPs occurs on a time scale of a few hundred femtoseconds. This observation is supported by the interfacial electronic‐energy alignment between the donor and acceptor moieties. Finally, due to the combination of large interfacial contact and ultrafast electron injection, this proposed platform of assembled thin films holds promise for a variety of solar cell architectures and other settings that principally rely on interfacial contact, such as photocatalysis.     

ROS‐Responsive Polyprodrug Nanoparticles for Triggered Drug Delivery and Effective Cancer Therapy

The application of nanoparticles (NPs) to drug delivery has led to the development of novel nanotherapeutics for the treatment of various diseases including cancer. However, clinical use of NP‐mediated drug delivery has not always translated into improved survival of cancer patients, in part due to the suboptimal properties of NP platforms, such as premature drug leakage during preparation, storage, or blood circulation, lack of active targeting to tumor tissue and cells, and poor tissue penetration. Herein, an innovative reactive oxygen species (ROS)‐responsive polyprodrug is reported that can self‐assemble into stable NPs with high drug loading. This new NP platform is composed of the following key components: (i) polyprodrug inner core that can respond to ROS for triggered release of intact therapeutic molecules, (ii) polyethylene glycol (PEG) outer shell to prolong blood circulation; and (iii) surface‐encoded internalizing RGD (iRGD) to enhance tumor targeting and tissue penetration. These targeted ROS‐responsive polyprodrug NPs show significant inhibition of tumor cell growth both in vitro and in vivo.     

A Heterostructure Coupling of Bioinspired,Adhesive Polydopamine,and Porous Prussian Blue Nanocubics as Cathode for High‐Performance Sodium‐Ion Battery

Prussian blue (PB) and its analogues are recognized as promising cathodes for rechargeable batteries intended for application in low‐cost and large‐scale electric energy storage. With respect to PB cathodes, however, their intrinsic crystal regularity, vacancies, and coordinated water will lead to low specific capacity and poor rate performance, impeding their application. Herein, nanocubic porous Na_xFeFe(CN)₆ coated with polydopamine (PDA) as a coupling layer to improve its electrochemical performance is reported, inspired by the excellent adhesive property of PDA. As a cathode for sodium‐ion batteries, the Na_xFeFe(CN)₆ electrode coupled with PDA delivers a reversible capacity of 93.8 mA h g^?1 after 500 cycles at 0.2 A g^?1, and a discharge capacity of 72.6 mA h g^?1 at 5.0 A g^?1. The sodium storage mechanism of this Na_xFeFe(CN)₆ coupled with PDA is revealed via in situ Raman spectroscopy. The first‐principles computational results indicate that Fe^II sites in PB prefer to couple with the robust PDA layer to stabilize the PB structure. Moreover, the sodium‐ion migration in the PB structure is enhanced after coating with PDA, thus improving the sodium storage properties. Both experiments and computational simulations present guidelines for the rational design of nanomaterials as electrodes for energy storage devices.     

Ultrastable Near‐Infrared Conjugated‐Polymer Nanoparticles for Dually Photoactive Tumor Inhibition

It is highly desired that satisfactory photoactive agents with ideal photophysical characteristics are explored for potent cancer phototherapeutics. Herein, bifunctional nanoparticles of low‐bandgap donor–acceptor (D–A)‐type conjugated‐polymer nanoparticles (CP‐NPs) are developed to afford a highly efficient singlet‐to‐triplet transition and photothermal conversion for near‐infrared (NIR) light‐induced photodynamic (PDT)/photothermal (PTT) treatment. CP‐NPs display remarkable NIR absorption with the peak at 782 nm, and perfect resistance to photobleaching. Photoexcited CP‐NPs undergo singlet‐to‐triplet intersystem crossing through charge transfer in the excited D–A system and simultaneous nonradiative decay from the electron‐deficient electron acceptor isoindigo derivative under single‐wavelength NIR light irradiation, leading to distinct singlet oxygen quantum yield and high photothermal conversion efficiency. Moreover, the CP‐NPs display effective cellular uptake and cytoplasmic translocation from lysosomes, as well as effective tumor accumulation, thus promoting severe light‐triggered damage caused by favorable reactive oxygen species (ROS) generation and potent hyperthermia. Thus, CP‐NPs achieve photoactive cell damage through their photoconversion ability for synergistic PDT/PTT treatment with tumor ablation. The proof‐of‐concept design of D–A‐type conjugated‐polymer nanoparticles with ideal photophysical characteristics provides a general approach to afford potent photoactive cancer therapy.     

WO3 Nanofiber‐Based Biomarker Detectors Enabled by Protein‐Encapsulated Catalyst Self‐Assembled on Polystyrene Colloid Templates

A novel catalyst functionalization method, based on protein‐encapsulated metallic nanoparticles (NPs) and their self‐assembly on polystyrene (PS) colloid templates, is used to form catalyst‐loaded porous WO₃ nanofibers (NFs). The metallic NPs, composed of Au, Pd, or Pt, are encapsulated within a protein cage, i.e., apoferritin, to form unagglomerated monodispersed particles with diameters of less than 5 nm. The catalytic NPs maintain their nanoscale size, even following high‐temperature heat‐treatment during synthesis, which is attributed to the discrete self‐assembly of NPs on PS colloid templates. In addition, the PS templates generate open pores on the electrospun WO₃ NFs, facilitating gas molecule transport into the sensing layers and promoting active surface reactions. As a result, the Au and Pd NP‐loaded porous WO₃ NFs show superior sensitivity toward hydrogen sulfide, as evidenced by responses (R_air/R_gas) of 11.1 and 43.5 at 350 °C, respectively. These responses represent 1.8‐ and 7.1‐fold improvements compared to that of dense WO₃ NFs (R_air/R_gas = 6.1). Moreover, Pt NP‐loaded porous WO₃ NFs exhibit high acetone sensitivity with response of 28.9. These results demonstrate a novel catalyst loading method, in which small NPs are well‐dispersed within the pores of WO₃ NFs, that is applicable to high sensitivity breath sensors.     

Layer‐by‐Layer Nanoparticles as an Efficient siRNA Delivery Vehicle for SPARC Silencing

Efficient and safe delivery systems for siRNA therapeutics remain a challenge. Elevated secreted protein, acidic, and rich in cysteine (SPARC) protein expression is associated with tissue scarring and fibrosis. Here we investigate the feasibility of encapsulating SPARC‐siRNA in the bilayers of layer‐by‐layer (LbL) nanoparticles (NPs) with poly(L‐arginine) (ARG) and dextran (DXS) as polyelectrolytes. Cellular binding and uptake of LbL NPs as well as siRNA delivery were studied in FibroGRO cells. siGLO‐siRNA and SPARC‐siRNA were efficiently coated onto hydroxyapatite nanoparticles. The multilayered NPs were characterized with regard to particle size, zeta potential and surface morphology using dynamic light scattering and transmission electron microscopy. The SPARC‐gene silencing and mRNA levels were analyzed using ChemiDOC western blot technique and RT‐PCR. The multilayer SPARC‐siRNA incorporated nanoparticles are about 200 nm in diameter and are efficiently internalized into FibroGRO cells. Their intracellular fate was also followed by tagging with suitable reporter siRNA as well as with lysotracker dye; confocal microscopy clearly indicates endosomal escape of the particles. Significant (60%) SPARC‐gene knock down was achieved by using 0.4 pmole siRNA/μg of LbL NPs in FibroGRO cells and the relative expression of SPARC mRNA reduced significantly (60%) against untreated cells. The cytotoxicity as evaluated by xCelligence real‐time cell proliferation and MTT cell assay, indicated that the SPARC‐siRNA‐loaded LbL NPs are non‐toxic. In conclusion, the LbL NP system described provides a promising, safe and efficient delivery platform as a non‐viral vector for siRNA delivery that uses biopolymers to enhance the gene knock down efficiency for the development of siRNA therapeutics.     

Metal‐Containing Polydopamine Nanomaterials: Catalysis,Energy, and Theranostics

Polydopamine (PDA) is a major type of artificial melanin material with many interesting properties such as antioxidant activity, free‐radical scavenging, high photothermal conversion efficiency, and strong metal‐ion chelation. The high affinity of PDA to a wide range of metals/metal ions has offered a new class of functional metal‐containing polydopamine (MPDA) nanomaterials with promising functions and extensive applications. Understanding and controlling the metal coordination environment is vital to achieve desirable functions for which such materials can be exploited. MPDA nanomaterials with metal/metal ions as the active functions are reviewed, including their synthesis and metal coordination environment and their applications in catalysis, batteries, solar cells, capacitors, medical imaging, cancer therapy, antifouling, and antibacterial coating. The current trends, limitations, and future directions of this area are also explored.