Dopamine Receptor-Mediated Binding and Cellular Uptake of Polydopamine-Coated Nanoparticles

Polydopamine-Cloaked Nanoarchitectonics of Prussian Blue Nanoparticles Promote Functional Recovery in Neonatal and Adult Ischemic Stroke Models

Ischemic stroke is a devastating disease and one of the leading causes of mortality worldwide. Overproduction of reactive oxygen species and inflammatory response contribute to secondary damage following ischemic insult. Nanozymes with robust anti-oxidative stress properties possess therapeutic possibility for ischemic insult. However, insufficiency of nanozyme accumulation in the neuronal mitochondria hindered their application. Herein, we constructed polydopamine-coated Prussian blue nanoparticles (PB@PDA NPs) to realize the targeting neuronal mitochondria for ischemic stroke, with the properties of antioxidant and anti-inflammation. After administration, much higher accumulation of PB@PDA NPs in the brain was observed compared to that in the PB NP group. Moreover, PB@PDA NPs effectively attenuated brain infarct than that of PB NPs in neonatal mice following hypoxia-ischemia (HI) insult. PB@PDA NPs mainly colocated with neuronal mitochondria in vivo and in vitro. Apart from attenuating oxidative stress, PB@PDA NPs also suppressed neuronal apoptosis and counteracted inflammation, which effectively promote a short- and long-term functional recovery in HI mice. Further, the therapeutic efficacy of PB@PDA NPs was also found in adult ischemic mice via tail vein injection. Collectively, these findings illustrate that PB@PDA NPs via system injection accumulate in neuronal mitochondria and are beneficial for ischemic stroke.

In Vivo Interactions of Nucleic Acid Nanostructures With Cells

Nucleic acid nanostructures, derived from the assembly of nucleic acid building blocks (e.g., plasmids and oligonucleotides), are important intracellular carriers of therapeutic cargoes widely utilized in preclinical nanomedicine applications, yet their clinical translation remains scarce. In the era of "translational nucleic acid nanotechnology", a deeper mechanistic understanding of the interactions of nucleic acid nanostructures with cells in vivo will guide the development of more efficacious nanomedicines. This review showcases the recent progress in dissecting the in vivo interactions of four key types of nucleic acid nanostructures (i.e., tile-based, origami, spherical nucleic acid, and nucleic acid nanogel) with cells in rodents over the past five years. Emphasis lies on the cellular-level distribution of nucleic acid nanostructures in various organs and tissues and the cellular responses induced by their cellular entry. Next, in the spirit of preclinical translation, this review features the latest interactions of nucleic acid nanostructures with cells in large animals and humans. Finally, the review offers directions for studying the interactions of nucleic acid nanostructures with cells from both materials and biology perspectives and concludes with some regulatory updates.

Microneedle-Delivered PDA@Exo for Multifaceted Osteoarthritis Treatment via PI3K-Akt-mTOR Pathway

Osteoarthritis (OA) is marked by cartilage deterioration, subchondral bone changes, and an inflammatory microenvironment. The study introduces the Microneedle-Delivered Polydopamine-Exosome (PDA@Exo MN), a therapeutic that not only preserves cartilage and promotes bone regeneration but also improves localized drug delivery through enhanced penetration capabilities. PDA@Exo MN shows strong reactive oxygen species (ROS) scavenging abilities and high biocompatibility, fostering osteogenesis and balancing anabolic and catabolic processes in cartilage. It directs macrophage polarization from M0 to the anti-inflammatory M2 phenotype. RNA sequencing of treated chondrocytes demonstrates restored cellular function and activated antioxidant responses, with modulated inflammatory pathways. The PI3K-AKT-mTOR pathway's activation, essential for PDA@Exo's effects, is confirmed via bioinformatics and Western blot. In vivo assessments robustly validate that PDA@Exo MN prevents cartilage degradation and OA progression, supported by histological assessments and micro-CT analysis, highlighting its disease-modifying impact. The excellent biocompatibility of PDA@Exo MN, verified through histological (H&E) and blood tests showing no organ damage, underscores its safety and efficacy for OA therapy, making it a novel and multifunctional nanomedical approach in orthopedics, characterized by organ-friendliness and biosecurity.

Melanin-Like Nanomedicine Functions as a Novel RPE Ferroptosis Inhibitor to Ameliorate Retinal Degeneration and Visual Impairment in Dry Age-Related Macular Degeneration

Ferrous ion accumulation and lethal oxidative stress mediate irreversible retinal pigment epithelial (RPE) cell ferroptosis and subsequent photoreceptor degeneration, a potential key pathogenic factor in the onset of dry age-related macular degeneration (dAMD), causing irreversible vision loss in the global elderly population. However, currently, no effective interventional treatment strategy exists in clinical practice. Herein, lesion site-targeted melanin-like nanoparticles, named ConA-MelNPs, are designed as a novel ferroptosis inhibitor for retinal degenerative diseases. ConA-MelNPs possessed chelating iron ion characteristics, alleviating severe mitochondrial damage caused by oxidative stress and protecting RPE cells from ferroptosis induced by sodium iodate (NaIO3). In a preclinical dAMD mouse model, a single intravitreal injection of ConA-MelNPs yielded significant responses in electroretinograms and visually-driven optomotor responses in visually impaired mice, resisting the challenge posed by secondary NaIO3-induced injuries, with the long-term sustainability of its therapeutic effect. Mechanistically, ConA-MelNPs achieve a therapeutic effect by interrupting the detrimental cascade involving "RPE cell ferroptosis, lethal oxidative stress, and microglial proinflammatory activation," affording the restoration of retinal homeostasis. The synthesized ConA-MelNPs demonstrated good biosafety, with no detected ophthalmic or systemic side effects. Collectively, ConA-MelNPs are proposed as a promising therapeutic option for atrophic retinal diseases such as dAMD.

NIR-Mediated Pyroelectric Catalysis for Sustained ROS/RNS Generation and Advanced Cancer Therapy In Vivo via Injectable Hydrogel

Exogenous electrical stimulation has attracted considerable attention due to the advantages of microelectric induction and subsequent biological effects such as actin reorganization and reactive oxygen species (ROS) generation. Herein, an injectable hydrogel of BPR-ARG@Gel (BAG) with pyroelectric BPR nanoparticle loading and l-arginine (ARG) introduction was fabricated for advanced cancer therapy in vivo. Due to the photothermal effect, the holes and electrons in BPR nanoparticles were separated to produce an open-circuit voltage and consequently catalyze water H2O to generate toxic superoxide (•O2-) and hydroxyl radicals (•OH). These ROS substances further oxidize ARG to produce NO for synergistic tumor treatments. The mice experiments indicated that the employment of BAG hydrogel incorporation with a near-infrared laser downregulated the heat shock protein and recruited immune cells with 5-fold-enhanced expression of proinflammatory cytokines of interferon-γ. It was also noteworthy that the injectable hydrogel of BAG substantially induced the generation of reactive oxygen/nitrogen species (ROS/RNS) with reliable biosafety and strong tumor inhibition. Overall, these findings have provided potentially new inspirations and a feasible strategy to translate this multifunctional hydrogel toward tumor therapy in a pyroelectric stimulation manner.

A novel peptide-drug conjugate for glioma-targeted drug delivery

The existence of the blood-brain barrier (BBB) and blood-brain tumor barrier (BBTB) greatly limits the application of chemotherapy in glioma. To address this challenge, an optimal drug delivery system must efficiently cross the BBB/BBTB and specifically deliver therapeutic drugs into glioma cells while minimizing systemic toxicity. Here we demonstrated that glucose-regulated protein 78 (GRP78) and dopamine receptor D2 were highly expressed in patient-derived glioma tissues, and dopamine receptors were highly expressed on the BBB. Subsequently, we synthesized a novel "Y"-shaped peptide and compared the effects of different linkers on the receptor affinity and targeting ability of the peptide. A peptide-drug conjugate (pHA-AOHX-VAP-doxorubicin conjugate, pHA-AOHX-VAP-DOX) with a better affinity for glioma cells and higher solubility was derived for glioma treatment. pHA-AOHX-VAP-DOX could cross both BBB and BBTB via dopamine receptor and GRP78 receptor, and finally target glioma cells, significantly prolonging the survival time of nude mice bearing intracranial glioma. Furthermore, pHA-AOHX-VAP-DOX significantly reduced the toxicity of DOX and increased the maximum tolerated dose (MTD). Collectively, this work paves a new avenue for overcoming multiple barriers and effectively delivering chemotherapeutic agents to glioma cells while providing key evidence to identify potential receptors for glioma-targeted drug delivery.

Photostabilities and anti-tumor effects of curcumin and curcumin-loaded polydopamine nanoparticles

Currently, the photostability of photosensitizer curcumin is the main bottleneck limiting their application, reducing the bioavailability of curcumin. Studying the effect of different light sources on the photostabilities of curcumin and loading it onto polydopamine nanocarriers with better biocompatibility will help improve its light utilization efficiency. In this study, we investigated the photostabilities of curcumin and a polydopamine-based nanoparticle (polydopamine-curcumin composite nanoparticles, PDA-Cur NPs) loaded with curcumin through in vitro and in vivo experiments to achieve better antitumor effects. The results demonstrated that curcumin has good photostability in dark, but with significant photodegradation rates in both red and blue light. Blue light has a faster effect on the photodegradation of curcumin, with a degradation rate of 42.1% after 10 minutes, which is about 1.7 times that of the red light. Our study successfully synthesized PDA-Cur NPs, demonstrating its ability to stably load and release curcumin, with a loading percentage of 65.7% after 2 hours and 41.9% release in 8 hours (pH 6.0). Compared with single curcumin treatments, the photodegradation rates of PDA-Cur NPs in red and blue light treatments were reduced by 46% and 50%, respectively. Meanwhile, PDA-Cur NPs exhibited remarkable antitumor efficacy due to PDT and promote apoptosis in cancer cells, which both better than that of single curcumin treatments. Moreover, in MCF-7 tumor-bearing mice, the PDA-Cur NPs led to significant tumor growth inhibition effects, without causing evident systemic damage in vivo. The findings highlight the potential of PDA-Cur NPs as anticancer photosensitizer with greatly increased utilization of curcumin in PDT.

Polydopamine-based plasmonic nanocomposites: rational designs and applications

Taking advantage of its adhesive nature and chemical reactivity, polydopamine (PDA) has recently been integrated with plasmonic nanoparticles to yield unprecedented hybrid nanostructures. With advanced architectures and optical properties, PDA-based plasmonic nanocomposites have showcased their potential in a wide spectrum of plasmon-driven applications, ranging from catalysis and chemical sensing, to drug delivery and photothermal therapy. The rational design of PDA-based plasmonic nanocomposites entails different material features of PDA and necessitates a thorough understanding of the sophisticated PDA chemistry; yet, there is still a lack of a systematic review on their fabrication strategies, plasmonic properties, and applications. In this Highlight review, five representative types of PDA-based plasmonic nanocomposites will be featured. Specifically, their design principles, synthetic strategies, and optical behaviors will be elucidated with an emphasis on the irreplaceable roles of PDA in the synthetic mechanisms. Together, their essential functions in diverse applications will be outlined. Lastly, existing challenges and outlooks on the rational design and assembly of next-generation PDA-based plasmonic nanocomposites will be presented. This Highlight review aims to provide synthetic insights and hints to inspire and aid researchers to innovate PDA-based plasmonic nanocomposites.

Systemic Delivery of Paclitaxel by Find-Me Nanoparticles Activates Antitumor Immunity and Eliminates Tumors

Local delivery of immune-activating agents has shown promise in overcoming an immunosuppressive tumor microenvironment (TME) and stimulating antitumor immune responses in tumors. However, systemic therapy is ultimately needed to treat tumors that are not readily locatable or accessible. To enable systemic delivery of immune-activating agents, we employ poly(lactic-co-glycolide) (PLGA) nanoparticles (NPs) with a track record in systemic application. The surface of PLGA NPs is decorated with adenosine triphosphate (ATP), a damage-associated molecular pattern to recruit antigen-presenting cells (APCs). The ATP-conjugated PLGA NPs (NPpD-ATP) are loaded with paclitaxel (PTX), a chemotherapeutic agent inducing immunogenic cell death to generate tumor antigens in situ. We show that the NPpD-ATP retains ATP activity in hostile TME and provides a stable "find-me" signal to recruit APCs. Therefore, the PTX-loaded NPpD-ATP helps populate antitumor immune cells in TME and attenuate the growth of CT26 and B16F10 tumors better than a mixture of PTX-loaded NPpD and ATP. Combined with anti-PD-1 antibody, PTX-loaded NPpD-ATP achieves complete regression of CT26 tumors followed by antitumor immune memory. This study demonstrates the feasibility of systemic immunotherapy using a PLGA NP formulation that delivers ICD-inducing chemotherapy and an immunostimulatory signal.

Virus-Inspired Glucose and Polydopamine (GPDA)-Coating as an Effective Strategy for the Construction of Brain Delivery Platforms

The ability of drugs to cross the blood-brain barrier (BBB) is crucial for treating central nervous system (CNS) disorders. Inspired by natural viruses, here we report a glucose and polydopamine (GPDA) coating method for the construction of delivery platforms for efficient BBB crossing. Such platforms are composed of nanoparticles (NPs) as the inner core and surface functionalized with glucose-poly(ethylene glycol) (Glu-PEG) and polydopamine (PDA) coating. Glu-PEG provides selective targeting of the NPs to brain capillary endothelial cells (BCECs), while PDA enhances the transcytosis of the NPs. This strategy is applicable to gold NPs (AuNPs), silica, and polymeric NPs, which achieves as high as 1.87% of the injected dose/g of brain in healthy brain tissues. In addition, the GPDA coating manages to deliver NPs into the tumor tissue in the orthotopic glioblastoma model. Our study may provide a universal strategy for the construction of delivery platforms for efficient BBB crossing and brain drug delivery.

Celebrating 60 Years of The Chinese University of Hong Kong: Research Highlights in Nanoscience and Nanotechnology

Recent breakthroughs and advances in nanoscience and nanotechnology have profoundly impacted young-generation education, accelerated knowledge transfer to enhance the quality of life, and improved environmental and economic sustainability. The Chinese University of Hong Kong (CUHK), a globally recognized education and research institute, has played a crucial role in promoting major strategic research directions in nanoscience, including translational biomedicine and information and automation technology, as well as environment and sustainability. To celebrate the 60th Anniversary of CUHK, we present this Virtual Issue that showcases the cutting-edge research at CUHK published in ACS Nano.

Activation of Dopamine Receptor D1 and Downstream Cellular Functions by Polydopamine

Polydopamine is a remarkable molecule that has gained considerable attention for its role in material surface modification, leading to an abundance of research in the biomaterial domain. While its widespread use is well documented, the molecule's potential cellular interactions have been less explored. In particular, dopamine serves as a neurotransmitter and a hormone that interacts with dopamine receptors in cells. Our study sheds light on the previously unexamined interaction between polydopamine and dopamine receptor D1 (DRD1). We discovered that polydopamine, along with its derivatives, such as levodopa and catechol, can activate DRD1─a function previously attributed solely to dopamine. Moreover, we found that polydopamine has the ability to influence cell behavior through the cAMP/PKA pathway, thereby affecting RhoA activity and stress fiber formation. These observations invite further consideration regarding the biological safety of polydopamine in biomedical contexts and also open avenues for new research directions in designing bioactive functional materials.

Polydopamine nanomaterials and their potential applications in the treatment of autoimmune diseases

The conventional treatment methods used for the management of autoimmune diseases (ADs) have limited efficacy and also exhibit significant side effects. Thus, identification of novel strategies to improve the efficacy and safety of ADs treatment is urgently required. Overactivated immune response and oxidative stress are common characteristics associated with ADs. Polydopamine (PDA), as a polymer material with good antioxidant and photothermal conversion properties, has displayed useful application potential against ADs. In addition, PDA possesses good biosafety, simple preparation, and easy functionalization, which is conducive for the pharmacological development of PDA nanomaterials with clinical transformation prospects. Here, we have first reviewed the preparation of PDA, the different functional integration strategies of PDA-based biomaterials, and their potential applications in ADs. Next, the mechanism of action of PDA in ADs has been elaborated in detail. Finally, the application opportunities and challenges linked with PDA nanomaterials for ADs treatment are discussed. This review is contributed to design reasonable and effective PDA nanomaterials for the diagnosis and treatment of ADs.

Cell-nano interactions of polydopamine nanoparticles

Polydopamine (PDA) nanoparticles (NPs) have diverse nanomedicine applications owing to their biocompatibility and abundant entry to cells. Yet, our knowledge in their interactions with cells was infrequently studied until recent years. This review presents the latest insights into the cell-nano interactions of PDA NPs, including their 'self-targeting' to dopamine receptors for cellular entry without the aid of ligands, in vitro 'self-therapeutic' cellular responses (antiferroptosis, macrophage polarization, and modulation of mitochondrial bioenergetics) in the absence of drugs, and in vivo cellular localization and pharmacological properties upon various routes of administration. This review concludes with our perspectives on the therapeutic promise of PDA NPs and the need for studies on PDA biochemistry, biodegradability, and protein adsorption.

Dual detection of human motion and glucose in sweat with polydopamine and glucose oxidase doped self-healing nanocomposite hydrogels

The detection of human motion and sweat composition are important for human health or sports training, so it is necessary to develop flexible sensors for monitoring exercise processes and sweat detection. Mussel secretion of adhesion proteins enables self-healing of byssus and adhesion to surfaces. We prepared Au nanoparticles@polydopamine (AuNPs@PDA) nanomaterials based on mussel-inspired chemistry and compounded them with polyvinyl alcohol (PVA) hydrogels to obtain PVA/AuNPs@PDA self-healing nanocomposite hydrogels. Dopamine (DA) was coated on the surface of AuNPs to obtain AuNPs based composite (AuNPs@PDA) and the AuNPs@PDA was implanted into the PVA hydrogels to obtain nanocomposite hydrogel through facile freeze-thaw cycle. Glucose oxidase (GOD) was added to the hydrogel matrix to achieve specific detection of glucose in sweat. The obtained hydrogels exhibit high deformability (573.7 %), excellent mechanical strength (550.3 KPa) and self-healing properties (85.1 %). The PVA/AuNPs@PDA hydrogel sensors exhibit quick response time (185.0 ms), wide strain sensing range (0-500 %), superior stability and anti-fatigue properties in motion detection. The detection of glucose had wide concentration detection range (1.0 μmol/L-200.0 μmol/L), low detection limits (0.9 μmol/L) and high sensitivity (24.4 μA/mM). This work proposes a reference method in dual detection of human exercise and sweat composition analysis.

Platelet-Membrane-Coated Polydopamine Nanoparticles for Neuroprotection by Reducing Oxidative Stress and Repairing Damaged Vessels in Intracerebral Hemorrhage

Intracerebral hemorrhage (ICH) has a high morbidity and mortality rate. Excessive reactive oxygen species (ROS) caused by primary and second brain injury can induce neuron death and inhibit neurological functional recovery after ICH. Therefore, exploring an effective way to noninvasively target hemorrhage sites to scavenge ROS is urgently needed. Inspired by the biological function of platelets to target injury vessel and repair injury blood vessels, platelet-membrane-modified polydopamine (Menp@PLT) nanoparticles are developed with targeting to hemorrhage sites of ICH. Results demonstrate that Menp@PLT nanoparticles can effectively achieve targeting to the location of intracranial hematoma. Furthermore, Menp@PLT with excellent anti-ROS properties can scavenge ROS and improve neuroinflammation microenvironment of ICH. In addition, Menp@PLT may play a role in decreasing hemorrhage volume by repairing injury blood vessels. Combining platelet membrane and anti-ROS nanoparticles for targeting brain hemorrhage sites provide a promising strategy for efficiently treating ICH.

Functionalization of and through Melanin: Strategies and Bio-Applications

A unique feature of nanoparticles for bio-application is the ease of achieving multi-functionality through covalent and non-covalent functionalization. In this way, multiple therapeutic actions, including chemical, photothermal and photodynamic activity, can be combined with different bio-imaging modalities, such as magnetic resonance, photoacoustic, and fluorescence imaging, in a theragnostic approach. In this context, melanin-related nanomaterials possess unique features since they are intrinsically biocompatible and, due to their optical and electronic properties, are themselves very efficient photothermal agents, efficient antioxidants, and photoacoustic contrast agents. Moreover, these materials present a unique versatility of functionalization, which makes them ideal for the design of multifunctional platforms for nanomedicine integrating new functions such as drug delivery and controlled release, gene therapy, or contrast ability in magnetic resonance and fluorescence imaging. In this review, the most relevant and recent examples of melanin-based multi-functionalized nanosystems are discussed, highlighting the different methods of functionalization and, in particular, distinguishing pre-functionalization and post-functionalization. In the meantime, the properties of melanin coatings employable for the functionalization of a variety of material substrates are also briefly introduced, especially in order to explain the origin of the versatility of melanin functionalization. In the final part, the most relevant critical issues related to melanin functionalization that may arise during the design of multifunctional melanin-like nanoplatforms for nanomedicine and bio-application are listed and discussed.

Polydopamine Nanoparticles Targeting Ferroptosis Mitigate Intervertebral Disc Degeneration Via Reactive Oxygen Species Depletion, Iron Ions Chelation, and GPX4 Ubiquitination Suppression

Intervertebral disc degeneration (IVDD)-induced lower back pain (LBP) is a common problem worldwide. The underlying mechanism is partially accredited to ferroptosis, based on sequencing analyses of IVDD patients from the gene expression omnibus (GEO) databases. In this study, it is shown that polydopamine nanoparticles (PDA NPs) inhibit oxidative stress-induced ferroptosis in nucleus pulposus (NP) cells in vitro. PDA NPs scavenge reactive oxygen species (ROS), chelate Fe²⁺ to mitigate iron overload, and regulate the expression of iron storage proteins such as ferritin heavy chain (FHC), ferritin, and transferrin receptor (TFR). More importantly, PDA NPs co-localize with glutathione peroxidase 4 (GPX4) around the mitochondria and suppress ubiquitin-mediated degradation, which in turn exerts a protective function via the transformation and clearance of phospholipid hydroperoxides. PDA NPs further down-regulate malondialdehyde (MDA) and lipid peroxide (LPO) production; thus, antagonizing ferroptosis in NP cells. Moreover, PDA NPs effectively rescue puncture-induced degeneration in vivo by targeting ferroptosis and inhibiting GPX4 ubiquitination, resulting in the upregulation of antioxidant pathways. The findings offer a new tool to explore the underlying mechanisms and a novel treatment strategy for IVDD-induced LBP.

Engineered Extracellular Vesicle-Encapsuled Nanoreactors for Effective Targeting and Cascade Killing of Cancer Cells

Nanomaterials have presented great potential for cancer therapy. However, their therapeutic efficacy is not always satisfied because of inefficient biocompatibility and targeting efficacy. Here, we report engineered extracellular vesicle (EV)-encapsuled nanoreactors for the targeting and killing of cancer cells. EVs are extracted from engineered cancer cells with surface N-glycans cut and intracellular microRNA-21 (miR-21) silenced to generate cancer-targeting membranes for the following coating of gold-polydopamine (PDA) core-shell nanoparticles. The encapsuled nanoparticles are decorated with doxorubicin (Dox), glucose oxidase (GOx), and miR-21-indicative DNA tags. Once endocytosed, the acidic pH, together with the photothermal effect of the PDA shell, can promote the release of Dox and GOx-catalyzed H₂O₂ generation/glucose consumption, while the DNA tags allow enhanced fluorescence imaging of miR-21 to indicate the targeting effect. The coadministration of EV-assisted delivery and cascade treatment represents a promising strategy for combination therapy.

Multifunctional Fe3O4 Nanoparticles Filled Polydopamine Hollow Rods for Antibacterial Biofilm Treatment

This work reports the use of mesoporous silica rods as templates for the step-wise preparation of multifunctional Fe₃O₄ NPs filled polydopamine hollow rods (Fe₃O₄@PDA HR). The capacity of as-synthesized Fe₃O₄@PDA HR as a new drug carrier platform was assessed by its loading and the triggered release of fosfomycin under various stimulations. It was found that the release of fosfomycin was pH dependent with ~89% of fosfomycin being released in pH 5 after 24 h, which was 2-fold higher than that in pH 7. The magnetic properties of Fe₃O₄ NPs and the photothermal properties of PDA enabled the triggered release of fosfomycin upon the exposure to rotational magnetic field, or NIR laser irradiation. Additionally, the capability of using multifunctional Fe₃O₄@PDA HR to eliminate preformed bacterial biofilm was demonstrated. Upon exposure to the rotational magnetic field, the biomass of a preformed biofilm was significantly reduced by 65.3% after a 20 min treatment with Fe₃O₄@PDA HR. Again, due to the excellent photothermal properties of PDA, a dramatic biomass decline (72.5%) was achieved after 10 min of laser exposure. This study offers an alternative approach of using drug carrier platform as a physical mean to kill pathogenic bacteria along with its traditional use for drug delivery.

Characterization of Electrospun Polysuccinimide-Dopamine Conjugates and Effect on Cell Viability and Uptake

Biocompatible nanofibrous systems made by electrospinning have been studied widely for pharmaceutical applications since they have a high specific surface and the capability to make the entrapped drug molecule amorphous, which increases bioavailability. By covalently conjugating drugs onto polymers, the degradation of the drug as well as the fast clearance from the circulation can be avoided. Although covalent polymer-drug conjugates have a lot of advantages, there is a lack of research focusing on their nano-formulation by electrospinning. In this study, polysuccinimide (PSI) based electrospun fibrous meshes conjugated with dopamine (DA) are prepared. Fiber diameter, mechanical properties, dissolution kinetics and membrane permeability are thoroughly investigated, as these are crucial for drug delivery and implantation. Dopamine release kinetics prove the prolonged release that influenced the viability and morphology of periodontal ligament stem cells (PDLSCs) and SH-SY5Y cells. The presence of dopamine receptors on both cell types is also demonstrated and the uptake of the conjugates is measured. According to flow cytometry analysis, the conjugates are internalized by both cell types, which is influenced by the chemical structure and physical properties. In conclusion, electrospinning of PSI-DA conjugates alters release kinetics, meanwhile, conjugated dopamine can play a key role in cellular uptake.

Electrospun fiber-mediated delivery of neurotrophin-3 mRNA for neural tissue engineering applications

Aligned electrospun fibers provide topographical cues and local therapeutic delivery to facilitate robust peripheral nerve regeneration. mRNA delivery enables transient expression of desired proteins that promote axonal regeneration. However, no prior work delivers mRNA from electrospun fibers for peripheral nerve regeneration applications. Here, we developed the first aligned electrospun fibers to deliver pseudouridine-modified (Ψ) neurotrophin-3 (NT-3) mRNA (ΨNT-3mRNA) to primary Schwann cells and assessed NT-3 secretion and bioactivity. We first electrospun aligned poly(L-lactic acid) (PLLA) fibers and coated them with the anionic substrates dextran sulfate sodium salt (DSS) or poly(3,4-dihydroxy-L-phenylalanine) (pDOPA). Cationic lipoplexes containing ΨNT-3mRNA complexed to JetMESSENGER® were then immobilized to the fibers, resulting in detectable ΨNT-3mRNA release for 28 days from all fiber groups investigated (PLLA+mRNA, 0.5DSS4h+mRNA, and 2pDOPA4h+mRNA). The 2pDOPA4h+mRNA group significantly increased Schwann cell secretion of NT-3 for 21 days compared to control PLLA fibers (p < 0.001-0.05) and, on average, increased Schwann cell secretion of NT-3 by ≥ 2-fold compared to bolus mRNA delivery from the 1µgBolus+mRNA and 3µgBolus+mRNA groups. The 2pDOPA4h+mRNA fibers supported Schwann cell secretion of NT-3 at levels that significantly increased dorsal root ganglia (DRG) neurite extension by 44% (p < 0.0001) and neurite area by 64% (p < 0.001) compared to control PLLA fibers. The data show that the 2pDOPA4h+mRNA fibers enhance the ability of Schwann cells to promote neurite growth from DRG, demonstrating this platform's potential capability to improve peripheral nerve regeneration. STATEMENT OF SIGNIFICANCE: Aligned electrospun fibers enhance axonal regeneration by providing structural support and guidance cues, but further therapeutic stimulation is necessary to improve functional outcomes. mRNA delivery enables the transient expression of therapeutic proteins, yet achieving local, sustained delivery remains challenging. Previous work shows that genetic material delivery from electrospun fibers improves regeneration; however, mRNA delivery has not been explored. Here, we examine mRNA delivery from aligned electrospun fibers to enhance neurite outgrowth. We show that immobilization of NT-3mRNA/JetMESSENGER® lipoplexes to aligned electrospun fibers functionalized with pDOPA enables local, sustained NT-3mRNA delivery to Schwann cells, increasing Schwann cell secretion of NT-3 and enhancing DRG neurite outgrowth. This study displays the potential benefits of electrospun fiber-mediated mRNA delivery platforms for neural tissue engineering.

Conjugated/nonconjugated alternating copolymers for enhanced NIR-II fluorescence imaging and NIR-II photothermal-ferrotherapy

Conjugated polymers hold great promise for NIR-II fluorescence imaging (FI)-guided NIR-II photothermal therapy (PTT) due to the advantages of easy modification of chemical structures and adjustable NIR absorption. However, to make use of these advantages, it is of paramount importance to formulate conjugated polymers with excellent solubility in organic solution, great NIR-II photothermal conversion efficiency, and high NIR-II fluorescence quantum yield. Herein, a new class of conjugated/nonconjugated alternating copolymers (CNACPs) is reported by introducing nonconjugated linkers into a conjugated backbone to modulate the extinction coefficient at 1064 nm and NIR-II fluorescence quantum yield. The NIR-II absorption, NIR-II emission, and NIR-II photothermal properties of the new CNACPs were studied. Interestingly, it is observed that longer nonconjugated linkers in CNACPs result in higher NIR-II fluorescence intensity with sufficient NIR-II absorption and NIR-II photothermal ability. With these newly developed CNACPs (BBT-C6), phototheranostic nanoparticles (BBTD6/Fe@PMA) are prepared through facile nanoprecipitation using PMA-AD-PEG as an iron ion chelator for NIR-II FI-guided NIR-II PTT/ferrotherapy synergistic therapy. In vitro and in vivo, BBTD6/Fe@PMA effectively inhibited 4T1 cells and tumor progression under 1064 nm laser irradiation. Consequently, this work provides new CNACPs by incorporating nonconjugated linkers into a conjugated backbone to design more effective NIR-II fluorescence imaging and NIR-II photothermal therapy agents.

The interfacial interactions of nanomaterials with human serum albumin

The fates of nanomaterials (NMs) in vivo are greatly dependent on their interactions with human serum proteins. However, the interfacial molecular details of NMs-serum proteins are still difficult to be probed. Herein, the molecular interaction details of human serum albumin (HSA) with Au and SiO₂ nanoparticles have been systematically interrogated and compared by using lysine reactivity profiling mass spectrometry (LRP-MS). We demonstrated the biocompatibility of Au is better than SiO₂ nanoparticles and the NMs surface charge state played a more important role than particle size in the combination of NMs-HSA at least in the range of 15-40 nm. Our results will contribute to the fundamental mechanism understanding of NMs-serum protein interactions as well as the NMs rational design.

Endogenous MicroRNA Accurate Diagnostics to Guide Photothermal Therapy

Developing an intelligent theranostic nanoplatform with satisfied diagnostic accuracy and therapeutic efficiency holds great promise for personalized nanomedicine. Herein, we constructed a smart nanodevice for the accurate diagnosis of endogenous cancer microRNA (miRNA) biomarkers and efficient photothermal therapy (PTT). The nanodevice was composed of polydopamine (PDA)-functionalized CuS nanosheets (CuS@PDA NSs) and three elaborate DNA hairpin probes (TDHPs). The CuS@PDA NSs acted as efficient delivery vehicles and photothermal agents. They provided a large surface area available for an efficient and facile loading of TDHPs and a high-fluorescence (FL) quenching performance to achieve an ultralow background signal. The intracellular miRNA triggered TDHPs to assemble into three-arm branched junction structures for a strong fluorescence recovery as output signals to discriminate cancer cells from normal cells with an excellent sensitivity. The CuS@PAD NSs showed a good photothermal conversion efficiency in the near-infrared II (NIR II) region to mediate a good photothermal performance to kill cancer cells. A remarkable antitumor therapeutic effect was achieved in vivo. This work integrated highly sensitive detection to endogenous cancer biomarkers and valid therapeutic potency to tumor-bearing mice, indicating its promising biomedical applications.

Fe(III)-Chelated Polydopamine Nanoparticles for Synergistic Tumor Therapies of Enhanced Photothermal Ablation and Antitumor Immune Activation

Both the low energy density of near-infrared (NIR) photothermal conversion during treatment and the recurrence and metastasis after local treatment have been the main obstacles and conundrums in polydopamine-mediated tumor photothermal therapy (PTT). Herein, On the basis of the enhancement of NIR absorption by ligand to metal charge transfer (LMCT) in transition-metal complexes and the activation of antitumor immunity by an appropriate concentration of Fe(III) ions, Fe(III)-chelated PDA nanoparticles (Fe-PDA NPs) with high loading and responsive release of iron ions were synthesized through a prechelation-polymerization method. First, Fe(III) chelated with the catechol groups in DA to form a mono-dopa-Fe(III) chelate, and then the polymerization of dopamine was initiated under alkaline conditions. The results revealed that the mono-dopa-Fe(III) chelate was still the main form of the Fe ion existing in Fe-PDA and was able to greatly enhance the light absorption behaviors of PDA in NIR, resulting a superior photothermal conversion ability (η = 55.5%). Moreover, the existence of Fe(III) also gave Fe-PDA a T₁-weighted MRI contrast-enhancement performance (r₁ = 7.668 mM^-1 s^-1) and it would enable the accurate ablation of primary tumors in vivo with Fe-PDA under NIR irradiation by means of the guidance of MRI and thermal imaging. Furthermore, Fe-PDA exhibited better H₂O₂-responsive biodegradability in comparison to PDA and easily released Fe ions in tumors, which could effectively promote the tumor-associated macrophage (TAM) repolarization to the M1 mode. TAM repolarization combined with the immunogenic cell death (ICD) induced by PTT could effectively enhance the efficacy of immunotherapy, preventing tumor recurrence and metastasis. The design of Fe-PDA nanoparticles should provide more inspiration for structural and functional improvements of melanin-based materials in tumor suppression.

Recent advances of nanodrug delivery system in the treatment of hematologic malignancies

Although the survival rate of hematological malignancies (HM) has increased in recent years, the unnecessary adverse effect to the body is usually generated by the traditional chemotherapy for HM due to the lack of specificity to tumor tissue. Nanodrug delivery systems have exhibited unique advantages in targetability, stability and reducing toxicity, attracting wide concern, which is expected to be the prevalent alternative for the treatment of HM. In this review, we systemically introduced the current therapeutic strategies and the categories of HM. Subsequently, five key factors including circulation, targeting, penetration, internalization and release involving in tailoring nanoparticles were demonstrated, followed by the introduction of the development of nanodrug delivery-traditional synthetic nanomaterilas, biomimetic cell membrane coating nanomaterials, cell-based nanomaterials as well as immunotherapy combined with nanodrug. Afterwards, the recent advances of nanodrug delivery system for the treatment of HM were introduced. Moreover, the challenge and prospect of nanodrug delivery system in treating HM were discussed. The promising drug delivery system will provide new therapeutic avenues for the treatment of HM.

Mammalian Cells Exocytose Alkylated Gold Nanoparticles via Extracellular Vesicles

Understanding the exocytosis of nanoparticles (NPs) from cells is valuable because it informs design rules of NPs that support desirable cellular retention for nanomedicine applications, but investigations into the mechanism for the exocytosis of NPs remain scarce. We elucidate the mechanism for the exocytosis of dodecyl-terminated, polyethylene glycol-coated gold NPs (termed "dodecyl-PEG-AuNP"). The Au core enables ultrastructural differentiation of the exocytosed NPs from the nearby extracellular vesicles (EVs). The PEG shell prevents interparticle agglomeration or aggregation that disfavors exocytosis. The minute amounts of alkyl chains on the PEG shell not only promote cellular uptake but also improve exocytosis by up to 4-fold higher probability and upregulate exocytosis- and vesicle-related genes. After entering Kera-308 keratinocytes and trafficking to multivesicular bodies and lysosomes, these NPs exit the cell predominantly via unconventional exocytosis, accompanied by enhanced secretion of sub-100 nm, CD81-enriched exosomes. The pathway for NP exocytosis and subpopulation of EVs that are secreted alongside the exocytosed NPs depends on dodecyl loading. This work provides insights into dissecting the mechanism of NP exocytosis and its relationship with EV secretion.

Protective Effect of Nanoparticles from Platycladi Cacumen Carbonisata on 2,4,6-Trinitrobenzene Sulfonic Acid (TNBS)-Induced Colitis in Rats

Aim: To evaluate the protective effects of Platycladi Cacumen Carbonisata-derived nanoparticles (PCC-NPs) against 2,4,6-trinitrobenzenesulfonic acid (TNBS)-induced ulcerative colitis (UC) in rats. Methods: This study developed and characterized novel PCC-NPs synthesized by a green and simple pyrolysis process using Platycladi Cacumen (PC) as the sole precursor. The UC model prepared with rectal instillation of TNBS was used to evaluate the potential efficacy of PCC-NPs, and the underlying mechanisms were preliminarily explored from the perspective of anti-inflammatory and antioxidative stress for the first time. Results: PCC-NPs exhibited low cytotoxicity, good dispersibility and copious surface functional groups. Nanoparticles with diameters ranging from 40-60 nm mainly manifested a therapeutic effect by downregulating tumour necrosis factor-α (TNF-α), interleukin-6 (IL-6) and upregulating interleukin-10 (IL-10). In addition, PCC-NPs relieved colon injury by inhibiting myeloperoxidase (MPO) activity, limiting the release of malondialdehyde (MDA) and increasing the activity of superoxide dismutase (SOD). Conclusion: Green synthetic PCC-NPs is a potential candidate as a complementary drug for intestinal inflammation of inflammatory bowel disease, and its regulatory mechanisms may be to balance the levels of pro-/anti-inflammatory cytokines and improve resistance to oxidative stress.

A Facile Method to Synthesize 3D Pomegranate-like Polydopamine Microspheres

Nanospheres have found versatile applications in the biomedical field; however, their possible harmful effects on immune and inflammatory systems are also a crucial concern. Inspired by a pomegranate structure, we demonstrated a novel structure for the nanostructured microspheres to overcome the drawbacks of nanospheres without compromising their merits. In this study, 3D pomegranate-like polydopamine microspheres (PDAMS) were synthesized by self-oxidative polymerization of dopamine hydrochloride. Herein, controlling the pH during polymerization led to synthesizing homogeneous agglomerated nano-sized spheres (400–2000 nm) and finally forming tunable and monodisperse micron-sized particles (21 µm) with uniform spherical shape porous microstructure. PDAMS interaction with the potential targets, Bone morphogenetic protein-2 (BMP2), Decorin, and Matrilin-1, was investigated via molecular calculations. Theoretical energy analysis revealed that PDAMS interaction with BMP2, Decorin, and Matrilin-1 is spontaneous, so that a protein layer formation on the PDAMS surface suggests application in bone and cartilage repair. It was also observed that PDAMS presented in-vitro degradation within 4 weeks. Here, disappearance of the UV-VIS spectrum peak at 280 nm is accompanied by the degradation of catechol groups. Pomegranate-like PDAMS support the biomimetic formation of hydroxyapatite-like layers, making them appropriate candidates for hard tissue applications. Herein, the appearance of peaks in XRD spectrum at 31.37, 39.57, 45.21, and 50.13° attributed to hydroxyapatite-like layers formation. All these results demonstrated that self-oxidative polymerization under a controllable pH can be a green and straightforward technique for preparing the pomegranate-like PDAMS and providing an innovative basis for further pre-clinical and clinical investigations.

Targeting Ferroptosis by Polydopamine Nanoparticles Protects Heart against Ischemia/Reperfusion Injury

Ferroptosis is a new form of regulated cell death depending on elevated iron (Fe²⁺) and lipid peroxidation levels. Myocardial ischemia/reperfusion (I/R) injury has been shown to be closely associated with ferroptosis. Therefore, antiferroptosis agents are considered to be a new strategy for managing myocardial I/R injury. Here, we developed polydopamine nanoparticles (PDA NPs) as a new type of ferroptosis inhibitor for cardioprotection. The PDA NPs features intriguing properties in inhibiting Fe²⁺ accumulation and restoring mitochondrial functions in H9c2 cells. Subsequently, we demonstrated that administration of PDA NPs effectively reduced Fe²⁺ deposition and lipid peroxidation in a myocardial I/R injury mouse model. In addition, the myocardial I/R injury in mice was alleviated by PDA NPs treatment, as demonstrated by reduced infarct size and improved cardiac functions. The present work indicates the therapeutic effects of PDA NPs against myocardial I/R injury via preventing ferroptosis.

A pH-Reversible Fluorescent Probe for in Situ Imaging of Extracellular Vesicles and Their Secretion from Living Cells

Our knowledge in how extracellular vesicles (EVs) are secreted from cells remains inadequate due to the limited technologies available for visualizing them in situ. We report a pH-reversible boron dipyrromethene (BODIPY) fluorescent probe for confocal imaging of EVs secreted from living cells without inducing severe cytotoxicity. This probe predominantly assumes a non-fluorescent leuco-BODIPY form under basic conditions, but it gradually switches to its fluorescent parent BODIPY form upon acidification; such pH transition empowers the imaging of acidic EVs (such as CD81-enriched exosomes and extracellular multivesicular bodies) in weakly basic culture medium and intracellular acidic precursor EVs in weakly basic cytoplasm, with minimal false positive signals frequently encountered for "always-on" dyes. Joint application of this probe with plasmid transfection reveals the secretion of some EVs from cellular pseudopodia via microtubule trackways. This probe may provide mechanistic insights into the extracellular transport of EVs and support the development of EV-based nanomedicines.

Alkyl-Terminated Gold Nanoparticles as a Self-Therapeutic Treatment for Psoriasis

We present a self-therapeutic nanoparticle for topical delivery to epidermal keratinocytes to prevent and treat psoriasis. Devoid of known chemical or biological antipsoriatic drugs, this sub-15 nm nanoparticle contains a 3 nm gold core and a shell of 1000 Da polyethylene glycol strands modified with 30% octadecyl chains. When it is applied to imiquimod-induced psoriasis mice without an excipient, the nanoparticle can cross the stratum corneum and preferentially enter keratinocytes. Applying the nanoparticles concurrently with imiquimod prevents psoriasis and downregulates genes that are enriched in the downstream of the interleukin-17 signaling pathway and linked to epidermis hyperproliferation and inflammation. Applying the nanoparticles after psoriasis is established treats the psoriatic skin as effectively as standard steroid and vitamin D analog-based therapy but without hair loss and skin wrinkling. The nanoparticles do not accumulate in major organs or induce long-term toxicity. Our nanoparticle offers a simple, safe, and effective alternative for treating psoriasis.