Synthesis and characterization of Fe3O4@SiO2@PDA@Ag core-shell nanoparticles and biological application on human lung cancer cell line and antibacterial strains

Novel magnetic and metallic nanoparticles garner much attention of researchers due to their biological, chemical and catalytic properties in many chemical reactions. In this study, we have successfully prepared a core-shell Fe3O4@SiO2@PDA nanocomposite wrapped with Ag using a simple synthesis method, characterised and tested on small cell lung cancer and antibacterial strains. Incorporating Ag in Fe3O4@SiO2@PDA provides promising advantages in biomedical applications. The magnetic Fe3O4 nanoparticles were coated with SiO2 to obtain negatively charged surface which is then coated with polydopamine (PDA). Then silver nanoparticles were assembled on Fe3O4@SiO2@PDA surface, which results in the formation core-shell nanocomposite. The synthesised nanocomposite were characterized using SEM-EDAX, dynamic light scattering, XRD, FT-IR and TEM. In this work, we report the anticancer activity of silver nanoparticles against H1299 lung cancer cell line using MTT assay. The cytotoxicity data revealed that the IC50 of Fe3O4@SiO2@PDA@Ag against H1299 lung cancer nanocomposites cells was 21.52 µg/mL. Furthermore, the biological data of nanocomposites against Gram-negative 'Pseudomonas aeruginosa' and Gram-positive 'Staphylococcus aureus' were carried out. The range of minimum inhibitory concentration was found to be 115 µg/mL where gentamicin was used as a standard drug. The synthesized AgNPs proves its supremacy as an efficient biomedical agent and AgNPs may act as potential beneficial molecule in lung cancer chemoprevention and antibacterial strains.

External Electrons Directly Stimulate Escherichia coli for Enhancing Biological Hydrogen Production

External electric field has the potential to influence metabolic processes such as biological hydrogen production in microorganisms. Based on this concept, we designed and constructed an electroactive hybrid system for microbial biohydrogen production under an electric field comprised of polydopamine (PDA)-modified Escherichia coli (E. coli) and Ni foam (NF). In this system, electrons generated from NF directly migrate into E. coli cells to promote highly efficient biocatalytic hydrogen production. Compared to that generated in the absence of electric field stimulation, biohydrogen production by the PDA-modified E. coli-based system is significantly enhanced. This investigation has demonstrated the mechanism for electron transfer in a biohybrid system and gives insight into precise basis for the enhancement of hydrogen production by using the multifield coupling technology.

Tuning the Chemical and Electrochemical Properties of Paper-Based Carbon Electrodes by Pyrolysis of Polydopamine

Electrochemical paper-based analytical devices represent an important platform for portable, low-cost, affordable, and decentralized diagnostics. For this kind of application, chemical functionalization plays a pivotal role to ensure high clinical performance by tuning surface properties and the area of electrodes. However, controlling different surface properties of electrodes by using a single functionalization route is still challenging. In this work, we attempted to tune the wettability, chemical composition, and electroactive area of carbon-paper-based devices by thermally treating polydopamine (PDA) at different temperatures. PDA films were deposited onto pyrolyzed paper (PP) electrodes and thermally treated in the range of 300-1000 °C. After deposition of PDA, the surface is rich in nitrogen and oxygen, it is superhydrophilic, and it has a high electroactive area. As the temperature increases, the surface becomes hydrophobic, and the electroactive area decreases. The surface modifications were followed by Raman, X-ray photoelectron microscopy (XPS), laser scanning confocal microscopy (LSCM), contact angle, scanning electron microscopy (SEM-EDS), electrical measurements, transmission electron microscopy (TEM), and electrochemical experiments. In addition, the chemical composition of nitrogen species can be tuned on the surface. As a proof of concept, we employed PDA-treated surfaces to anchor [AuCl4]- ions. After electrochemical reduction, we observed that it is possible to control the size of the nanoparticles on the surface. Our route opens a new avenue to add versatility to electrochemical interfaces in the field of paper-based electrochemical biosensors.

Electrospun Fiber Membrane with the Dual Affinity of Chelation and Covalent Interactions for the Efficient Enrichment of Glycoproteins

As important biomarkers of many diseases, glycoproteins are of great significance to biomedical science. It is essential to develop efficient glycoprotein enrichment platforms and investigate their adsorption mechanism. In this work, a conspicuous enrichment strategy for glycoproteins was developed by using an electrospun fiber membrane wrapped with polydopamine (PDA) and modified with 3-aminophenylboronic acid and nickel ions, named PAN/DA@PDA@APBA/Ni. The enrichment characteristics of PAN/DA@PDA@APBA/Ni toward glycoproteins were explored through adsorption behavior. Thanks to the existence of two sites of interaction (metal ion chelation and boronate affinity), PAN/DA@PDA@APBA/Ni exhibited significant enrichment capacity for glycoproteins, ovalbumin (604.6 mg/g), and human immunoglobulin G (331.0 mg/g). The adsorption kinetic results of glycoprotein ovalbumin on PAN/DA@PDA@APBA/Ni conform to the pseudo-first-order kinetic model in the first adsorption stage, while the second half adsorption stage is more in line with the pseudo-second-order kinetic model. Moreover, the physical characteristics of PAN/DA@PDA@APBA/Ni and subsequent adsorption experiments on electrospun fiber modified with only phenylboronic acid or nickel ions both confirmed two sites of interaction (metal ion chelation and boronate affinity, respectively). Furthermore, a stepwise elution method with dual-affinity interaction was designed and successfully applied to enrich glycoproteins in real biological samples. This work provides an idea for sample pretreatment, especially for the design of dual-affinity materials in glycoproteins enrichment.

Nucleation-Inhibited Emulsion Interfacial Assembled Polydopamine Microvesicles as Artificial Antigen-Presenting Cells

Albeit microemulsion systems have emerged as efficient platforms for fabricating tunable nano/microstructures, lack of understanding on the emulsion-interfacial assembly hindered the control of fabrication. Herein, a nucleation-inhibited microemulsion interfacial assembly method is proposed, which deviates from conventional interfacial nucleation approaches, for the synthesis of polydopamine microvesicles (PDA MVs). These PDA MVs exhibit an approximate diameter of 1 µm, showcasing a pliable structure reminiscent of cellular morphology. Through modifications of antibodies on the surface of PDA MVs, their capacity as artificial antigen presentation cells is evaluated. In comparison to solid nanoparticles, PDA MVs with cell-like structures show enhanced T-cell activation, resulting in a 1.5-fold increase in CD25 expression after 1 day and a threefold surge in PD-1 positivity after 7 days. In summary, the research elucidates the influence of nucleation and interfacial assembly in microemulsion polymerization systems, providing a direct synthesis method for MVs and substantiating their effectiveness as artificial antigen-presenting cells.

Polydopamine-Mediated Metal-Organic Frameworks Modification for Improved Biocompatibility

Engineered nanomaterials are promising in biomedical application. However, insufficient understanding of their biocompatibility at the cellular and organic levels prevents their widely biomedical applications. Metal-organic frameworks (MOFs) have attracted increasing attention in recent years. In this work, zeolitic imidazolate framework-8 (ZIF-8) and polydopamine (PDA)-modified ZIF-8 are chosen as model nanomaterials due to its emergent role in nanomedicine. In vitro, the results demonstrate that the PDA coating greatly alleviates the cytotoxicity of ZIF-8 to RAW264.7, LO2, and HST6, which represent three different cell types in liver organs. Mechanistically, ZIF-8 entering into the cells can greatly induce the reactive oxygen species generation, which subsequently induces cell cycle delay and autophagy, ultimately leads to enhanced cytotoxicity. Further, human umbilical vein endothelial cells model and zebrafish embryos assay also confirm that PDA can compromise the ZIF-8 toxicity significantly. This study reveals that PDA-coated MOFs nanomaterials show great potential in nano-based drug delivery systems .

In Situ Construction of Zinc-Mediated Fe, N-Codoped Hollow Carbon Nanocages with Boosted Oxygen Reduction for Zn-Air Batteries

The rational design of bifunctional oxygen electrocatalysts with unique morphology and luxuriant porous structure is significant but challenging for accelerating the reaction kinetics of rechargeable Zn-air batteries (ZABs). Herein, zinc-mediated Fe, N-codoped carbon nanocages (Zn-FeNCNs) are synthesized by pyrolyzing the polymerized iron-doped polydopamine on the surface of the ZIF-8 crystal polyhedron. The formation of the chelate between polydopamine and Fe serves as the covering layer to prevent the porous carbon nanocages from collapsing and boosts enough exposure and utilization of metal-based active species during carbonization. Furthermore, both the theoretical calculation and experimental results show that the strong interaction between polyhedron and polydopamine facilitates the evolution of high-activity zinc-modulated FeNx sites and electron transportation and then stimulates the excellent bifunctional catalytic activity for oxygen evolution reaction (OER) and oxygen reduction reaction (ORR). As expected, the Zn-air battery with Zn-FeNCNs as an air cathode displays a superior power density (256 mW cm-2) and a high specific capacity (813.3 mA h gZn-1), as well as long-term stability over 1000 h. Besides, when this catalyst is applied to the solid-state battery, the device exhibited outstanding mechanical stability and a high round-trip efficiency under different bending angles.

Amphiphilic Interlayer Regulated Interfacial Polymerization for Constructing Polyamide Nanofiltration Membranes with High Perm-Selectivity of Mono-/Divalent Salts

High-quality thin-film composite (TFC) membranes with high selectivity and permeability have great significance owing to their practical applications, specifically for the accurate differentiation of monovalent and divalent ions. However, the trade-off effect between selectivity and permeability is still a big challenge due to the difficult structure adjustment of the selective layer. Herein, polydopamine (PDA) functionalized with a hydrophobic long alkane chain was first explored as a functional amphiphilic interlayer to synthesize high-quality TFC membranes via a confined interfacial polymerization (IP) reaction. The amphiphilic interlayer not only restricted the formation of the polyamide (PA) matrix in the pores of the substrate but also accelerated spatially more homogeneous polymerization and formed a PA active layer with a more uniform pore size distribution. The method may provide an effective principle for the construction of versatile polyamide-based membranes with high perm-selectivity on various supports. The NaCl/Na2SO4 separation factor of the D-8/PA membrane reached as high as 204.07, while the flux increased up to 25.71 L m-2 h-1 bar-1. This progress provides a more feasible way for the construction of high-quality TFC membranes with a devisable and creative amphiphilic interlayer for industrial application.

MgO@polydopamine Nanoparticle-Loaded Photothermal Microneedle Patches Combined with Chitosan Gel Dressings for the Treatment of Infectious Wounds

As for wound drug delivery, microneedles (MNs) have attracted wide attention. However, while effective at increasing the depth of drug delivery, traditional MNs often have limited drug loads and have difficulty penetrating scabs on wounds. Herein, we develop a drug delivery system combining MgO@polydopamine (MgO@PDA) nanoparticle-loaded photothermal MN patches and chitosan (CS) gel to inhibit the formation of scabs and deliver sufficient drugs into deep tissue. When inserted into the wound, the MN system can keep the wound bed moist and weakly acidic to inhibit the formation of scabs and accelerate wound closure. The released MgO@PDA nanoparticles from both the tips and the backing layer, which immensely increase the drug load, continuously release Mg2+ in the moist, weakly acidic wound bed, promoting tissue migration and the formation of microvessels. MgO@PDA nanoparticles show excellent antibacterial activity under near-infrared irradiation synergized with the CS gel, and the PDA coating can also overcome the adverse effects of oxidative stress. Through in vitro and in vivo experiments, the MN system showed remarkable antibacterial, antioxidant, anti-inflammatory, and pro-angiogenic effects, indicating its potential in the treatment of infectious wounds.

Surface Bioengineering of Mo2Ga2C MAX Phase to Develop Blended Loose Nanofiltration Membranes for Textile Wastewater Treatment

The potential of blended loose nanofiltration membranes (LNMs) to fractionate dyes and inorganic salts in textile wastewater has become a focus of attention in recent years. In this research work, we fabricated LNMs based on polysulfone (PSf) membranes blended with l-histidine amino acid-functionalized Mo2Ga2C MAX phase (His-MAX). Scanning electron microscopy (SEM), atomic force microscopy (AFM), attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), contact angle, ζ-potential, porosity, and pore size analyses were employed to characterize the LNMs. Blending 0.75 wt % of His-MAX additive with the PSf tailored the LNM's features by making it more water-friendly, increasing its porosity, enlarging its pores, and making its surface smoother. The pure water flux of 127.6 L/m2 h was achieved by LNM containing 0.75 wt % His-MAX, which was 2.5 times greater than the bare one. The mentioned LNM displayed a flux recovery ratio (FRR) of 68.27 and 98.57, 98.31, and 99.7% rejections for Direct red 23, Acid brown 75, and Reactive blue 21 solutions (100 mg/L), respectively. The 0.75 wt % His-MAX LNM could reject 99.1% of dye and 11.5% of salt while maintaining an FRR of 91.19% after four cycles of filtering a binary mixture solution containing Reactive blue 21 and Na2SO4. These findings highlight the potential of the fabricated LNM for desalinating dye solutions.

Mesoporous Silicon Nanoparticles with Liver-Targeting and pH-Response-Release Function Are Used for Targeted Drug Delivery in Liver Cancer Treatment

This article aims to develop an aspirin-loaded double-modified nano-delivery system for the treatment of hepatocellular carcinoma. In this paper, mesoporous silica nanoparticles (MSN) were prepared by the "one-pot two-phase layering method", and polydopamine (PDA) was formed by the self-polymerization of dopamine as a pH-sensitive coating. Gal-modified PDA-modified nanoparticles (Gal-PDA-MSN) were synthesized by linking galactosamine (Gal) with actively targeted galactosamine (Gal) to PDA-coated MSN by a Michael addition reaction. The size, particle size distribution, surface morphology, BET surface area, mesoporous size, and pore volume of the prepared nanoparticles were characterized, and their drug load and drug release behavior in vitro were investigated. Gal-PDA-MSN is pH sensitive and targeted. MSN@Asp is different from the release curves of PDA-MSN@Asp and Gal-PDA-MSN@Asp, the drug release of PDA-MSN@Asp and Gal-PDA-MSN@Asp accelerates with increasing acidity. In vitro experiments showed that the toxicity and inhibitory effects of the three nanodrugs on human liver cancer HepG2 cells were higher than those of free Asp. This drug delivery system facilitates controlled release and targeted therapy.

High-Performance Bioinspired Microspheres for Boosting Dental Adhesion

Dental adhesives are widely used in daily practice for minimally invasive restorative dentistry but suffer from bond degradation and biofilm attack. Bio-inspired by marine mussels having excellent surface-adhesion capability and high chemical affinity of polydopamine (PDA) to metal ions, herein, experimental zinc (Zn)-containing polydopamine-based adhesive formulation, further being referred to as "Zn-PDA@SiO2 "-incorporated adhesive is proposed as a novel dental adhesive. Different Zn contents (5 and 10 mm) of Zn-PDA@SiO2 are prepared. Considering the synergistic effect of Zn and PDA, Zn-PDA@SiO2 not only presents excellent antibacterial potential and notably inhibits enzymatic activity (soluble and matrix-bound proteases), but also exhibits superior biocompatibility and biosafety in vitro/vivo. The long-term bond stability is substantially improved by adding 5 wt% 5 mm Zn-PDA@SiO2 to the primer. The aged bond strength of the experimentally formulated dental adhesives applied in self-etch (SE) bonding mode is 1.9 times higher than that of the SE gold-standard adhesive. Molecular dynamics calculations indicate the stable formation of covalent bonds, Zn-assisted coordinative bonds, and hydrogen bonds between PDA and collagen. Overall, this bioinspired dental adhesive provides an avenue technology for innovative biomedical applications and has already revealed promising perspectives for dental restorative dentistry.

Polydopamine Blending Increases Human Cell Proliferation in Gelatin-Xanthan Gum 3D-Printed Hydrogel

BACKGROUND

Gelatin-xanthan gum (Gel-Xnt) hydrogel has been previously modified to improve its printability; now, to increase its ability for use as cell-laden 3D scaffolds (bioink), polydopamine (PDA), a biocompatible, antibacterial, adhesive, and antioxidant mussel-inspired biopolymer, has been added (1-3% v/v) to hydrogel.

METHODS

Control (CT) and PDA-blended hydrogels were used to print 1 cm2 grids. The hydrogels' printability, moisture, swelling, hydrolysis, and porosity were tested after glutaraldehyde (GTA) crosslinking, while biocompatibility was tested using primary human-derived skin fibroblasts and spontaneously immortalized human keratinocytes (HaCaT). Keratinocyte or fibroblast suspension (100 µL, 2.5 × 105 cells) was combined with an uncrosslinked CT and PDA blended hydrogel to fabricate cylinders (0.5 cm high, 1 cm wide). These cylinders were then cross-linked and incubated for 1, 3, 7, 14, and 21 days. The presence of cells within various hydrogels was assessed using optical microscopy.

RESULTS AND DISCUSSION

PDA blending did not modify the hydrogel printability or physiochemical characteristics, suggesting that PDA did not interfere with GTA crosslinking. On the other hand, PDA presence strongly accelerated and increased both fibroblast and keratinocyte growth inside. This effect seemed to be linked to the adhesive abilities of PDA, which improve cell adhesion and, in turn, proliferation.

CONCLUSIONS

The simple PDA blending method described could help in obtaining a new bioink for the development of innovative 3D-printed wound dressings.

Bioinspired BSA@polydopamine@Fe Nanoprobe with Self-Purification Capacity for Targeted Magnetic Resonance Imaging of Acute Kidney Injury

Contrast-enhanced magnetic resonance imaging (CE-MRI) of acute kidney injury (AKI) is severely hindered by the poor targeting capacity and potential toxicity of current contrast agents. Herein, we propose one-step fabrication of a bovine serum albumin@polydopamine@Fe (BSA@PDA@Fe, BPFe) nanoprobe with self-purification capacity for targeted CE-MRI of AKI. BSA endows the BPFe nanoprobe with renal tubule-targeting ability, and PDA is capable of completely inhibiting the intrinsic metal-induced reactive oxygen species (ROS), which are always involved in Fe/Mn-based agents. The as-prepared nanoprobe owns a tiny size of 2.7 nm, excellent solubility, good T1 MRI ability, superior biocompatibility, and powerful antioxidant capacity. In vivo CE-MRI shows that the BPFe nanoprobe can accumulate in the renal cortex due to the reabsorption effect toward the serum albumin. In the AKI model, impaired renal reabsorption function can be effortlessly detected via the diminishment of renal cortical signal enhancement. More importantly, the administration of the BPFe nanoprobe would not aggravate renal damage of AKI due to the outstanding self-purification capacity. Besides, the BPFe nanoprobe is employed for CE-MR angiography to visualize fine vessel structures. This work provides an MRI contrast agent with good biosafety and targeting ability for CE-MRI of kidney diseases.

Materiobiomodulated ROS Therapy for De Novo Hair Growth

Hair loss is characterized by the inability of hair follicles (HFs) to enter the telogen-anagen transition (TAT) and lack of de novo HFs. Current pharmaceutical therapies and surgical modalities have been largely limited to regulating hair regrowth efficiently without side effects and lacking treatment compliance. Here, this work proposes a materiobiomodulation therapy (MBMT), wherein polydopamine (PDA) nanoparticles with redox activity can be modulated to have a stoichiometric ROS (H2 O2 ) donating ability. These nanoparticles can intracellularly deliver ROS with high-efficiency via the clathrin-dependent endocytosis process. Utilizing homozygote transgenic HyPerion (a genetically-encoded H2 O2 biosensor) mice, this work also achieves in vivo dynamic monitoring of intracellular H2 O2 elevation induced by ROS donators. Subcutaneous administration with ROS donators results in rapid onset of TAT and subsequent hair regrowth with a specific ROS "hormesis effect." Mechanistically, ROS activate β-catenin-dependent Wnt signaling, upregulating hair follicle stem cell expression. This work further develops a microneedles patch for transdermal ROS delivery, demonstrating long-term, low-dose ROS release. Unlike photobiomodulation therapy (PBMT), MBMT requires no external stimuli, providing a convenient and efficient approach for clinical hair loss treatment. This material-HF communication implicates new avenues in HF-related diseases, achieving targeted ROS delivery with minimal side effects.

Combined ROS Responsive Polydopamine-Coated Berberine Nanoparticles Effective Against Ulcerative Colitis in Mouse Model

Introduction

Enhancing the efficacy of berberine (BBR) in the treatment of ulcerative colitis (UC) through the development of dopamine-coated berberine nanoparticles (PDA@BBR NPs) with ROS-responsive and adhesive properties.

Methods

Berberine nanoparticles (BBR NPs) were synthesized using the nonsolvent precipitation method, and their surfaces were coated with polydopamine (PDA) through oxidative polymerization. The PDA@BBR NPs were characterized by transmission electron microscopy (TEM), size analysis, and zeta potential analysis. Drug loading and encapsulation efficiency were analyzed using fluorescence spectroscopy. The responsiveness of these nanoparticles to reactive oxygen species (ROS) was assessed in vitro, while their adhesive properties and therapeutic efficacy on UC were evaluated in vivo.

Results

Physicochemical property studies showed that PDA coated BBR NPs nanoparticles have good dispersion and stability. In vitro results showed that PDA@BBR NPs could prolong the retention time of the drug at the colonic site and could realize the gradual drug release under ROS environment. In addition, animal studies showed that PDA@BBR NPs exhibited significant anti-inflammatory effects on DSS-induced colitis and effectively reduced intestinal mucosal damage.

Conclusion

PDA@BBR NPs are ROS-responsive nanoparticles that adhere well and have a high drug loading capacity. They have shown therapeutic effects in mice with UC, indicating that this formulation may be a promising treatment option.

Efficient Removal and Recovery of Ag from Wastewater Using Charged Polystyrene-Polydopamine Nanocoatings and Their Sustainable Catalytic Application in 4-Nitrophenol Reduction

This study addresses the long-standing challenges of removing and recovering trace silver (Ag) ions from wastewater while promoting their sustainable catalysis utilization. We innovatively developed a composite material by combining charged sulfonated polystyrene (PS) with a PDA coating. This composite serves a dual purpose: effectively removing and recovering trace Ag+ from wastewater and enabling reused Ag for sustainable applications, particularly in the catalytic reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). The PS-PDA demonstrated exceptional selectivity to trace Ag+ recycling, which is equal to 14 times greater than the commercial ion exchanger. We emphasize the distinct roles of different charged functional groups in Ag+ removal and catalytic reduction performance. The negatively charged SO3H groups exhibited the remarkable ability to rapidly enrich trace Ag ions from wastewater, with a capacity 2-3 times higher than that of positively-N+(CH3)3Cl and netural-CH2Cl-modified composites; this resulted in an impressive 96% conversion of 4-NP to 4-AP within just 25 min. The fixed-bed application further confirmed the effective treatment capacity of approximately 4400 L of water per kilogram of adsorbent, while maintaining an extremely low effluent Ag+ concentration of less than 0.1 mg/L. XPS investigations provided valuable insights into the conversion of Ag+ ions into metallic Ag through the enticement of negatively charged SO3H groups and the in situ reduction facilitated by PDA. This breakthrough not only facilitates the efficient extraction of Ag from wastewater but also paves the way for its environmentally responsible utilization in catalytic reactions.

Evaluation of Reactive Oxygen Species Scavenging of Polydopamine with Different Nanostructures

Reactive oxygen species (ROS) play an important role in cellular metabolism and many oxidative stress-related diseases, while excessive accumulation of ROS will lead to genetic changes in cells and promote the occurrence of inflammatory diseases or cell death. Nature-inspired polydopamine (PDA) with tailored nanostructures emerges as an ROS scavenger and is considered as an effective approach to inflammation-related diseases. However, the effects of nanoparticle structure on PDA scavenging efficacy and efficiency remain uncovered. In this work, three typical PDA nanoparticles including solid PDA, mesoporous PDA, and hollow PDA are synthesized, and of which physiochemical properties are characterized. Furthermore, their ROS scavenging performance is investigated by in vitro evaluation of radical removal. Among the three nanoparticles, mesoporous PDA is demonstrated to have the highest scavenging capability, mainly due to its specific surface area. Finally, the study on three in vivo inflammation models is constructed. The results confirm that mesoporous PDA is the most potent scavenger of ROS and more effective in reducing reperfusion injury, improving renal function, and preventing periodontitis progression, respectively. Together with the good biosafety and biocompatibility profiles, PDA nanoparticles, mesoporous PDA in particular, can be a promising avenue of ROS scavenging in fight against the inflammatory diseases.

Polydopamine Nanosystems in Drug Delivery: Effect of Size, Morphology, and Surface Charge

Recently, drug delivery strategies based on nanomaterials have attracted a lot of interest in different kinds of therapies because of their superior properties. Polydopamine (PDA), one of the most interesting materials in nanomedicine because of its versatility and biocompatibility, has been widely investigated in the drug delivery field. It can be easily functionalized to favor processes like cellular uptake and blood circulation, and it can also induce drug release through two kinds of stimuli: NIR light irradiation and pH. In this review, we describe PDA nanomaterials' performance on drug delivery, based on their size, morphology, and surface charge. Indeed, these characteristics strongly influence the main mechanisms involved in a drug delivery system: blood circulation, cellular uptake, drug loading, and drug release. The understanding of the connections between PDA nanosystems' properties and these phenomena is pivotal to obtain a controlled design of new nanocarriers based on the specific drug delivery applications.

Superhydrophobic Nanoparticles: An Efficiently Selective Adsorbent for Surfactant-Like Contaminants from Complex Wastewater Matrices

Surfactant-like contaminants (SLCs) with distinctive amphiphilic structures have become a global concern in wastewater due to their toxicity and persistency. Despite extensive efforts, achieving efficient and selective SLCs removal remains challenging because of their wide range of molecular weights and complex functional group compositions. Superhydrophobic nanoparticles can potentially tackle this challenge by targeting the long oleophilic chains of SLCs. However, conventional contact angle measurements hinder hydrophobicity characterization and corresponding selectivity research because of the powder morphology of nanoparticles. Herein, the authors offered information regarding the distribution of water molecular probes in surfaces and proposed a quantitative characterization approach based on low-field nuclear magnetic resonance. Through synthesizing superhydrophobic and hydrophilic polydopamine nanospheres with similar morphologies, the selective adsorption potential of superhydrophobic nanoparticles for SLCs is systematically demonstrated. As revealed by the interaction mechanisms, the superhydrophobic surface of nanospheres increased its affinity and selectivity for SLCs adsorption by enhancing hydrophobic interactions. Superhydrophobic modification achieved ten times the adsorption capacity of sodium dodecyl benzene sulfonate, an exemplified surfactant, compared with pristine nanoparticles. By regulated self-polymerization, the superhydrophobic nanospheres are coated onto the surface of a 3D sponge and enable efficient selective SLCs adsorption from highly polluted leachate matrices with long-term stability and reusability.

Recent Development and Applications of Polydopamine in Tissue Repair and Regeneration Biomaterials

The various tissue damages are a severe problem to human health. The limited human tissue regenerate ability requires suitable biomaterials to help damage tissue repair and regeneration. Therefore, many researchers devoted themselves to exploring biomaterials suitable for tissue repair and regeneration. Polydopamine (PDA) as a natural and multifunctional material which is inspired by mussel has been widely applied in different biomaterials. The excellent properties of PDA, such as strong adhesion, photothermal and high drug-loaded capacity, seem to be born for tissue repair and regeneration. Furthermore, PDA combined with different materials can exert unexpected effects. Thus, to inspire researchers, this review summarizes the recent and representative development of PDA biomaterials in tissue repair and regeneration. This article focuses on why apply PDA in these biomaterials and what PDA can do in different tissue injuries.

Melanin-Inspired Composite Materials: From Nanoarchitectonics to Applications

Synthetic melanin is a mimic of natural melanin analogue with intriguing properties such as metal-ion chelation, redox activity, adhesion, and broadband absorption. Melanin-inspired composite materials are formulated by assembly of melanin with other types of inorganic and organic components to target, combine, and build up the functionality, far beyond their natural capabilities. Developing efficient and universal methodologies to prepare melanin-based composite materials with unique functionality is vital for their further applications. In this review, we summarize three types of synthetic approaches, predoping, surface engineering, and physical blending, to access various melanin-inspired composite materials with distinctive structure and properties. The applications of melanin-inspired composite materials in free radical scavenging, bioimaging, antifouling, and catalytic applications are also reviewed. This review also concludes current challenges that must be addressed and research opportunities in future studies.

Establishment of Polydopamine-Modified HK-2 Cell Membrane Chromatography and Screening of Active Components from Plantago asiatica L

Cell membrane chromatography (CMC) has been widely recognized as a highly efficient technique for in vitro screening of active compounds. Nevertheless, conventional CMC approaches suffer from a restricted repertoire of cell membrane proteins, making them susceptible to oversaturation. Moreover, the binding mechanism between silica gel and proteins primarily relies on intermolecular hydrogen bonding, which is inherently unstable and somewhat hampers the advancement of CMC. Consequently, this investigation aimed to establish a novel CMC column that could augment protein loading, enhance detection throughput, and bolster binding affinity through the introduction of covalent bonding with proteins. This study utilizes polydopamine (PDA)-coated silica gel, which is formed through the self-polymerization of dopamine (DA), as the carrier for the CMC column filler. The objective is to construct the HK-2/SiO2-PDA/CMC model to screen potential therapeutic drugs for gout. To compare the quantity and characteristics of Human Kidney-2 (HK-2) cell membrane proteins immobilized on SiO2-PDA and silica gel, the proteins were immobilized on both surfaces. The results indicate that SiO2-PDA has a notably greater affinity for membrane proteins compared to silica gel, resulting in a significant improvement in detection efficiency. Furthermore, a screening method utilizing HK-2/SiO2-PDA/CMC was utilized to identify seven potential anti-gout compounds derived from Plantago asiatica L. (PAL). The effectiveness of these compounds was further validated using an in vitro cell model of uric acid (UA) reabsorption. In conclusion, this study successfully developed and implemented a novel CMC filler, which has practical implications in the field.

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.

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.

Natural Multifunctional Silk Microcarriers for Noise-Induced Hearing Loss Therapy

Noise-induced hearing loss (NIHL) is a common outcome of excessive reactive oxygen species in the cochlea, and the targeted delivery of antioxidants to the inner ear is a potential therapeutic strategy. In this paper, a novel natural biomaterials-derived multifunctional delivery system using silk fibroin-polydopamine (PDA)-composited inverse opal microcarriers (PDA@SFMCs) is presented for inner ear drug delivery and NIHL therapy. Due to their large specific surface area and interpenetrating nanochannels, PDA@SFMCs can rapidly load active biomolecules making them a convenient medium for the storage and delivery of such molecules. In addition, surface modification of PDA enables the microcarriers to remain in the round window niche, thus facilitating the precise local and directed delivery of loaded drugs. Based on these features, it is demonstrated here that n-acetylcysteine-loaded silk microcarriers have satisfactory antioxidant properties on cells and can successfully prevent NIHL in guinea pigs. These results indicate that the natural multifunctional silk microcarriers are promising agents for local inner ear drug delivery in the clinic.

AgNPs-Modified Polylactic Acid Microneedles: Preparation and In Vivo/In Vitro Antimicrobial Studies

OBJECTIVE

To prepare polylactic acid microneedles (PLAMNs) with sustained antibacterial effect to avoid skin infection caused by traditional MNs-based biosensors.

METHODS

Silver nanoparticles (AgNPs) were synthesized using an in-situ reduction process with polydopamine (PDA). PLAMNs were fabricated using the hot-melt method. A series of pressure tests and puncture experiments were conducted to confirm the physicochemical properties of PLAMNs. Then AgNPs were modified on the surface of PLAMNs through in-situ reduction of PDA, resulting in the formation of PLAMNs@PDA-AgNPs. The in vitro antibacterial efficacy of PLAMNs@PDA-AgNPs was evaluated using agar diffusion assays and bacterial liquid co-culture approach. Wound healing and simulated long-term application were performed to assess the in vivo antibacterial effectiveness of PLAMNs@PDA-AgNPs.

RESULTS

The MNs array comprised 169 tiny needle tips in pyramidal rows. Strength and puncture tests confirmed a 100% puncture success rate for PLAMNs on isolated rat skin and tin foil. SEM analysis revealed the integrity of PLAMNs@PDA-AgNPs with the formation of new surface substances. EDS analysis indicated the presence of silver elements on the surface of PLAMNs@PDA-AgNPs, with a content of 14.44%. Transepidermal water loss (TEWL) testing demonstrated the rapid healing of micro-pores created by PLAMNs@PDA-AgNPs, indicating their safety. Both in vitro and in vivo tests confirmed antibacterial efficacy of PLAMNs@PDA-AgNPs.

CONCLUSIONS

In conclusion, the sustained antibacterial activity exhibited by PLAMNs@PDA-AgNPs offers a promising solution for addressing skin infections associated with MN applications, especially when compared to traditional MN-based biosensors. This advancement offers significant potential for the field of MN technology.

The In Vivo Fate of Polycatecholamine Coated Nanoparticles Is Determined by a Fibrinogen Enriched Protein Corona

Polycatecholamine coatings have attracted significant attention in the past 10 years owing to their ability to functionalize a wide range of materials. Here we apply the use of such coatings to drug nanocrystals, made from a poorly soluble drug compound, to postfunctionalize the nanocrystal surface with the aim of providing steric stabilization and extending their circulation time after intravenous injection. We show that both polydopamine and polynorepinephrine can be used to successfully modify drug nanocrystals and subsequently incorporate end-functionalized PEG to the surface. Even though high grafting densities of PEG were achieved, we observed rapid clearance and increased liver uptake for polycatecholamine functionalized drug nanocrystals. Using both surface sensitive model systems and protein corona profiling, we determine that the rapid clearance was correlated with an increase in adsorption of proteins involved in coagulation to the polycatecholamine surface, with fibrinogen being the most abundant. Further analysis of the most abundant proteins revealed a significant increase in thiol-rich proteins on polycatecholamine coated surfaces. The observed interaction with coagulation proteins highlights one of the current challenges using polycatecholamines for drug delivery but might also provide insights to the growing use of these materials in hemostatic applications.

Fluorescent bioinspired albumin/polydopamine nanoparticles and their interactions with Escherichia coli cells

Inspired by the eumelanin aggregates in human skin, polydopamine nanoparticles (PDA NPs) are promising nanovectors for biomedical applications, especially because of their biocompatibility. We synthesized and characterized fluorescent PDA NPs of 10-25 nm diameter based on a protein containing a lysine-glutamate diad (bovine serum albumin, BSA) and determined whether they can penetrate and accumulate in bacterial cells to serve as a marker or drug nanocarrier. Three fluorescent PDA NPs were designed to allow for tracking in three different wavelength ranges by oxidizing BSA/PDA NPs (Ox-BSA/PDA NPs) or labelling with fluorescein 5-isothiocyanate (FITC-BSA/PDA NPs) or rhodamine B isothiocyanate (RhBITC-BSA/PDA NPs). FITC-BSA/PDA NPs and RhBITC-BSA/PDA NPs penetrated and accumulated in both cell wall and inner compartments of Escherichia coli (E. coli) cells. The fluorescence signals were diffuse or displayed aggregate-like patterns with both labelled NPs and free dyes. RhBITC-BSA/PDA NPs led to the most intense fluorescence in cells. Penetration and accumulation of NPs was not accompanied by a bactericidal or inhibitory effect of growth as demonstrated with the Gram-negative E. coli species and confirmed with a Gram-positive bacterial species (Staphylococcus aureus). Altogether, these results allow us to envisage the use of labelled BSA/PDA NPs to track bacteria and carry drugs in the core of bacterial cells.

PVDF Nanofiber Modified with ZnO Nanowires/Polydopamine for the Treatment of Sewage Containing Heavy Metals, Organic Dyes, and Bacteria

In various countries worldwide, the issue of wastewater contamination poses a significant threat due to its intricate composition of heavy metals, organic dyes, and microorganisms, thereby complicating the purification process. Consequently, researchers have expressed considerable interest in materials capable of eliminating organic, heavy metal, and microbial pollutants. This study focuses on the fabrication of a water purification membrane (PDA/ZnO-NWs/PVDF) with a hierarchical structure and the ability to remove multiple pollutants. The membrane was created by modifying poly(vinylidene fluoride) (PVDF) nanofiber with zinc oxide nanowires (ZnO-NWs) and reinforcing it with polydopamine (PDA). The experimental results demonstrate that the PDA/ZnO-NWs/PVDF membrane exhibits a range of functionalities, including long-lasting superhydrophilicity, Cu(II) adsorption, photocatalytic degradation, and antibacterial ability. The manipulation of the DA synthesis procedure allows for the adjustment of the wettability, adsorption, and photocatalytic and antibacterial activities of the PDA/ZnO-NWs/PVDF composite. According to the Langmuir isotherm, the maximum Cu(II) adsorption capacity of the PDA/ZnO-NWs/PVDF membrane is determined to be 65.75 mg/g, which is significantly higher (27.26 mg/g) than that of the ZnO-NWs/PVDF membrane (38.49 mg/g). The PDA/ZnO-NWs/PVDF composite exhibited a notable degradation capacity toward rhodamine B under natural sunlight, reaching a maximum of 5.97 mg/g. Additionally, the degradation rate achieved during daylight hours was as high as 90.42%. Furthermore, the antibacterial efficacy of the PDA/ZnO-NWs/PVDF composite against both Gram-positive and Gram-negative bacteria approached 100%. This work presents a promising approach for the treatment of wastewater containing various coexisting contaminants.

[Preparation of berberine-naringin dual drug-loaded composite microspheres and evaluation of their antibacterial-osteogenic properties]

Objective

To develop a drug-loaded composite microsphere that can simultaneously release the berberine (BBR) and naringin (NG) to repair infectious bone defects.

Methods

The NG was loaded on mesoporous microspheres (MBG) to obtain the drug-loaded microspheres (NG-MBG). Then the dual drug-loaded compound microspheres (NG-MBG@PDA-BBR) were obtained by wrapping NG-MBG with polydopamine (PDA) and modifying the coated PDA with BBR. The composite microspheres were characterized by scanning electron microscopy, X-ray diffraction, specific surface area and pore volume analyzer, and Fourier transform infrared spectroscopy; the drug loading rate and release of NG and BBR were measured; the colony number was counted and the bacterial inhibition rate was calculated after co-culture with Staphylococcus aureus and Escherichia coli for 12 hours to observe the antibacterial effect; the biocompatibility was evaluated by live/dead cell fluorescence staining and cell counting kit 8 assay after co-culture with rat's BMSCs for 24 and 72 hours, respectively, and the osteogenic property was evaluated by alkaline phosphatase (ALP) staining and alizarin red staining after 7 and 14 days, respectively.

Results

NG-MBG@PDA-BBR and three control microspheres (MBG, MBG@PDA, and NG-MBG@PDA) were successfully constructed. Scanning electron microscopy showed that NG-MBG@PDA-BBR had a rough lamellar structure, while MBG had a smooth surface, and MBG@PDA and NG-MBG@PDA had a wrapped agglomeration structure. Specific surface area analysis showed that MBG had a mesoporous structure and had drug-loading potential. Low angle X-ray diffraction showed that NG was successfully loaded on MBG. The X-ray diffraction pattern contrast showed that all groups of microspheres were amorphous. Fourier transform infrared spectroscopy showed that NG and BBR peaks existed in NG-MBG@PDA-BBR. NG-MBG@PDA-BBR had good sustained drug release ability, and NG and BBR had early burst release and late sustained release. NG-MBG@PDA-BBR could inhibit the growth of Staphylococcus aureus and Escherichia coli, and the antibacterial ability was significantly higher than that of MBG, MBG@PDA, and NG-MBG@PDA ( P<0.05). But there was a significant difference in biocompatibility at 72 hours among microspheres ( P<0.05). ALP and alizarin red staining showed that the ALP positive area and the number of calcium nodules in NG-MBG@PDA-BBR were significantly higher than those of MBG and NG-MBG ( P<0.05), and there was no significant difference between NG-MBG@PDA and NG-MBG@PDA ( P>0.05).

Conclusion

NG-MBG@PDA-BBR have sustained release effects on NG and BBR, indicating that it has ideal dual performance of osteogenesis and antibacterial property.

A Synergistic Antibacterial Study of Copper-Doped Polydopamine on Ti3C2Tx Nanosheets with Enhanced Photothermal and Fenton-like Activities

In response to the trend of drug-resistant and super bacteria, the existing single antibacterial methods are not sufficient to kill bacteria, and the development of multifunctional antibacterial nanomaterials is urgent. Our study aims to construct copper-doped polydopamine-coated Ti3C2Tx (CuPDA@Ti3C2Tx) with an enhanced photothermal property and Fenton-like activity. The nanocomposite hydrogel consisting of CuPDA@Ti3C2Tx and alginate can improve the antioxidant activity of two-dimensional MXene nanosheets by coating them with a thin layer of PDA nanofilm. Meanwhile, Cu ions are adsorbed through the coordination of PDA-rich oxygen-containing functional groups and amino groups. Calcium ions were further used to crosslink sodium alginate to obtain antibacterial hydrogel materials with combined chemotherapy and photothermal therapy properties. The photothermal conversion efficiency of CuPDA@Ti3C2Tx is as high as 57.7% and the antibacterial rate of Escherichia coli reaches 96.12%. The photothermal effect leads to oxidative stress in bacteria, increases cell membrane permeability, and a high amount of ROS and copper ions enter the interior of the bacteria, causing protein denaturation and DNA damage, synergistically leading to bacterial death. Our study involves a multifunctional synergistic antibacterial nanodrug platform, which is conducive to the development of high-performance antibacterial agents and provides important research ideas for solving the problem of drug-resistant bacteria.

Antioxidant-Engineered Milk-Derived Extracellular Vesicles for Accelerating Wound Healing via Regulation of the PI3K-AKT Signaling Pathway

Inspired by the experience of relieving inflammation in infants with milk, antioxidant-engineered milk-derived extracellular vesicles (MEVs) are developed to evaluate their potential for accelerating wound healing. In this work, MEVs with polydopamines (PDA) are engineered using the co-extrusion method. Subsequently, the authors incorporated them into a Schiff-based crosslink hydrogel, forming a skin dosage form that could facilitate the wound healing process. The antioxidant properties of PDA assist in the anti-inflammatory function of engineered MEVs, while the gel provides better skin residency. The PDA@MEVs+GEL formulation exhibits excellent biocompatibility, pro-angiogenic capacity, and antioxidant ability in vitro. Furthermore, in vivo experiments demonstrate its efficacy in wound repair and inflammation inhibition. Mechanistically, PDA@MEVs+GEL simultaneously promotes the growth, migration, and anti-inflammation of 3T3 cells by activating PI3K-AKT pathway. Moreover, PDA@MEVs+GEL exhibits enhanced functionality in promoting wound healing in vivo, attributed to its ability to inhibit inflammation, stimulate angiogenesis, and promote collagen synthesis. In conclusion, this study delves into the mechanism of MEVs and underscores the improved efficacy of engineered extracellular vesicles. Additionally, the feasibility and prospect of engineered MEVs in treating skin wounds are verified, suggesting that antioxidant-engineered MEVs could be a promising therapeutic agent for wound healing applications.

Enhancement of protein immobilization on polydimethylsiloxane using a synergistic combination of polydopamine and micropattern surface modification

Understanding protein interactions at biointerfaces is critical for the improved design of biomaterials and medical devices. Polydimethylsiloxane (PDMS) is used for numerous device applications, and surface modifications can enhance protein immobilization and the response to cells. A multifunctional approach combining topographical and biochemical modifications was applied to PDMS by fabricating 10-20 µm scale patterns onto PDMS surfaces and by coating with polydopamine (PDA). The modifications were confirmed by surface characterization and bovine serum albumin (BSA), fibrinogen (Fg), and fetuin-A (Fet-A) were radiolabeled with 125I. The amounts of protein attached to the surface before and after elution with sodium dodecyl sulfate (SDS) were quantified from single and complex multi-protein solutions to determine protein stability and competitive binding. The PDA coatings were the most stable and capable of immobilizing the highest levels of all proteins. Furthermore, combinations of PDA coatings with the smallest micropatterns provided an additional improvement, enhancing the amount immobilized and the stability. The adsorption of BSA and Fg from plasma demonstrated competitive binding and possible orientation changes, respectively. It was determined that Fet-A, a less studied protein, adsorbed from plasma at low levels, but the adsorption from fetal bovine serum (FBS) was significantly greater, providing important quantification data from radiolabeling that is relevant to many cell culture studies. Overall, combining topography and PDA modification has a synergistic effect on improving protein immobilization. These findings provide new insight on the quantities of proteins bound to PDMS and PDA coatings with implications for cell interactions in various biotechnology and medical applications.

Flexible Conductive Decellularized Fish Skin Matrix as a Functional Scaffold for Myocardial Infarction Repair

Engineering cardiac patches are proven to be effective in myocardial infarction (MI) repair, but it is still a tricky problem in tissue engineering to construct a scaffold with good biocompatibility, suitable mechanical properties, and solid structure. Herein, decellularized fish skin matrix is utilized with good biocompatibility to prepare a flexible conductive cardiac patch through polymerization of polydopamine (PDA) and polypyrrole (PPy). Compared with single modification, the double modification strategy facilitated the efficiency of pyrrole polymerization, so that the patch conductivity is improved. According to the results of experiments in vivo and in vitro, the scaffold can promote the maturation and functionalization of cardiomyocytes (CMs). It can also reduce the inflammatory response, increase local microcirculation, and reconstruct the conductive microenvironment in infarcted myocardia, thus improving the cardiac function of MI rats. In addition, the excellent flexibility of the scaffold, which enables it to be implanted in vivo through "folding-delivering-re-stretehing" pathway, provides the possibility of microoperation under endoscope, which avoids the secondary damage to myocardium by traditional thoracotomy for implantation surgery.

Metronidazole-loaded polydopamine nanomedicine with antioxidant and antibacterial bioactivity for periodontitis

Aim: This study focused on treating periodontitis with bacterial infection and local over accumulation of reactive oxygen species. Materials & methods: Polydopamine nanoparticles (PDA NPs) were exploited as efficient carriers for encapsulated metronidazole (MNZ). The therapeutic efficacy and biocompatibility of PDA@MNZ NPs were investigated through both in vitro and in vivo studies. Results: The nanodrug PDA@MNZ NPs were successfully fabricated, with well-defined physicochemical characteristics. In vitro, the PDA@MNZ NPs effectively eliminated intracellular reactive oxygen species and inhibited the growth of Porphyromonas gingivalis. Moreover, the PDA@MNZ NPs exhibited synergistic therapy for periodontitisin in vivo. Conclusion: PDA@MNZ NPs were confirmed with exceptional antimicrobial and antioxidant functions, offering a promising avenue for synergistic therapy in periodontitis.

Imaging-Guided Photoacoustic Immunotherapy Based on the Polydopamine-Functionalized Black Phosphorus Nanocomposites

Phototherapy has great application prospects in superficial tumors, such as melanoma, esophageal cancer, and breast carcinoma, owing to the advantages of noninvasiveness, high spatiotemporal selectivity, and less side effects. However, classical phototherapies including photodynamic and photothermal therapy still need to settle the bottleneck problems of poor efficacy, inevitable thermal damage, and a high rate of postoperative recurrence. In this study, we developed a nanocomposite with excellent optical properties and immune-stimulating properties, termed PBP@CpG, which was obtained by functionalizing black phosphorus (BP) with polydopamine and further adsorbing CpG. Benefiting from the protection of polydopamine against BP, ideal light absorption, and photoacoustic conversion properties, PBP@CpG not only enables precisely delineation of the tumor region with photoacoustic imaging but also powerfully disrupts the plasma membrane and cytoskeleton of tumor cells with a photoacoustic cavitation effect. In addition, we found that the photoacoustic cavitation effect was also capable of inducing immunogenic cell death and remarkably strengthening the antitumor immune response upon cooperating with immune adjuvant CpG. Therefore, PBP@CpG was expected to provide a promising nanoplatform for optical theranostics and herald a new strategy of photoimmunotherapy based on the photoacoustic cavitation effects and immunostimulatory effect.

Pyrrole-Doped Polydopamine-Pyrrole (PDA-nPY) Nanoparticles with Tunable Size and Improved NIR Absorption for Photothermal Therapy

Polydopamine (PDA) as a melanin-like biomimetic material with excellent biocompatibility, full spectrum light absorption capacity and antioxidation property has been extensively applied in the biomedical field. Based on the high reactivity of dopamine (DA), exploiting new strategies to fabricate novel PDA-based nano-biomaterials with controllable size and improved performance is valuable and desirable. Herein, we reported a facile way to synthesize pyrrole-doped polydopamine-pyrrole nanoparticles (PDA-nPY NPs) with tunable size and enhanced near-infrared (NIR) absorption capacity through self-oxidative polymerization of DA with PY in an alkaline ethanol/H2O/NH4OH solution. The PDA-nPY NPs maintain excellent biocompatibility and surface reactivity as PDA. By regulating the volume of added PY, PDA-150PY NPs with a smaller size (<100 nm) and four-fold higher absorption intensity at 808 nm than that of PDA can be successfully fabricated. In vitro and in vivo experiments effectively further demonstrate that PDA-150PY NPs can effectively inhibit tumor growth and completely thermally ablate a tumor. It is believed that these PY doped PDA-nPY NPs can be a potential photothermal (PT) agent in biomedical application.

Mussel-Inspired Calcium Alginate/Polyacrylamide Dual Network Hydrogel: A Physical Barrier to Prevent Postoperative Re-Adhesion

Intrauterine adhesions (IUA) has become one of the main causes of female infertility. How to effectively prevent postoperative re-adhesion has become a clinical challenge. In this study, a mussel-inspired dual-network hydrogel was proposed for the postoperative anti-adhesion of IUA. First, a calcium alginate/polyacrylamide (CA-PAM) hydrogel was prepared via covalent and Ca2+ cross-linking. Benefiting from abundant phenolic hydroxyl groups, polydopamine (PDA) was introduced to further enhance the adhesion ability and biocompatibility. This CA-PAM hydrogel immersed in 10 mg/mL dopamine solution possessed remarkable mechanical strength (elastic modulus > 5 kPa) and super stretchability (with a breaking elongation of 720%). At the same time, it showed excellent adhesion (more than 6 kPa). Surprisingly, the coagulation index of the hydrogel was 27.27 ± 4.91, demonstrating attractive coagulation performance in vitro and the potential for rapid hemostasis after surgery.

Oxidative Stress in Xenograft Mouse Model Exposed to Dendrimers Decorated Polydopamine Nanoparticles and Targeted Chemo- and Photothermal Therapy

Polydopamine (PDA)-based nanostructures are used for biomedical purposes. A hybrid drug nanocarrier based on a PDA decorated with polyamidoamine (PAMAM) dendrimers G 3.0 (DG3) followed by a connection with glycol (PEG) moieties, folic acid (FA), and drug doxorubicin (DOX) was used for combined chemo- and photothermal therapy (CT-PTT) of liver cancer. Oxidative stress plays a crucial role in the development of cancer, and PDA seems to have the ability to both donate and accept electrons. We investigated oxidative stress in organs by evaluating oxidative stress markers in vivo. In the liver, the level of reduced glutathione (GSH) was lower and the level of Trolox equivalent antioxidant capacity (TEAC) was higher in the group receiving doxorubicin encapsulated in PDA nanoparticles with phototherapy (PDA@DG3@PEG@FA@DOX + PTT) compared to the control group. The concentration of thiobarbituric acid reactive substances (TBARS) in livers, was higher in the group receiving PDA coated with PAMAM dendrimers and functionalized with PEG and FA (PDA@DG3@PEG@FA) than in other groups. Markers in the brain also showed lower levels of GSH in the PDA@DG3@PEG@FA group than in the control group. Markers of oxidative stress indicated changes in the organs of animals receiving PDA nanoparticles with PAMAM dendrimers functionalized with FA in CT-PTT of liver cancer under in vivo conditions. Our work will provide insights into oxidative stress, which can be an indicator of the toxic potential of PDA nanoparticles and provide new strategies to improve existing therapies.

Synthesis, Characterization, and Induced Osteogenic Differentiation Effect of Collagen Membranes Functionalized by Polydopamine/Graphene Oxide for Bone Tissue Engineering

Collagen is one of the most common natural absorbable polymers, which is widely used as a barrier membrane in biomedical fields due to its many desirable biological properties. However, absorbable membranes such as collagen have their own disadvantages such as unpredictable degradation rates, poor rigidity leading to tissue collapse, and limited osteogenic properties and cell adhesion. In this study, a modified collagen membrane with a polydopamine-graphene oxide (PDA/GO) complex was synthesized to improve the characteristics of collagen for bone tissue engineering. The successful synthesis of PDA/GO on collagen membranes was verified using X-ray photoelectron spectroscopy (XPS) and attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR). The wettability of PDA/GO-modified collagen membranes was considerably improved based on the characterization by water contact angle compared to the uncoated membranes and surface coatings solely by either PDA or GO. The modified PDA/GO coating also enhanced the mechanical properties such as tensile strength and biodegradation rate of collagen membranes. In addition, the PDA/GO coating effectively enhanced the biocompatibility of collagen membranes as verified by the enhanced proliferation and adhesion of human bone marrow stem cells (hBMSCs). Additionally, the effects of PDA/GO coating on the osteogenic differentiation of hBMSCs on collagen membranes were investigated through alkaline phosphatase (ALP) activity and reverse transcription-quantitative polymerase chain reaction (RT-qPCR). The PDA/GO coating on collagen membranes resulted in a significant increase in osteogenic properties compared with the uncoated collagen membranes. According to the results of the current study, the combination of PDA and GO-modified collagen membranes could be used for bone tissue engineering and biomedical applications.

2D and 3D Micropatterning of Mussel-Inspired Functional Materials by Direct Laser Writing

This work addresses the critical need for multifunctional materials and substrate-independent high-precision surface modification techniques that are essential for advancing microdevices and sensing elements. To overcome existing limitations, the versatility of mussel-inspired materials (MIMs) is combined with state-of-the-art multiphoton direct laser writing (DLW) microfabrication. In this way, 2D and 3D MIM microstructures of complex designs are demonstrated with sub-micron to micron resolution and extensive post-functionalization capabilities. This study includes polydopamine (PDA), mussel-inspired linear, and dendritic polyglycerols (MI-lPG and MI-dPG), allowing their direct microstructure on the substrate of choice with the option to tailor the patterned topography and morphology in a controllable manner. The functionality potential of MIMs is demonstrated by successfully immobilizing and detecting single-stranded DNA on MIM micropattern and nanoarray surfaces. In addition, easy modification of MIM microstructure with silver nanoparticles without the need of any reducing agent is shown. The methodology developed here enables the integration of MIMs in advanced applications where precise surface functionalization is essential.

Constructing a Photothermal and Quaternary Ammonium Cation Bactericidal Platform onto SEBS for Synergistic Therapy

Poly(styrene-b-(ethylene-co-butylene)-b-styrene) (SEBS) with eminent elasticity, thermoplastic ability, and biological stability has aroused great interest in the medical area. However, bacteria can easily adhere to the hydrophobic SEBS surface to cause medical device-related infections. In this work, SEBS is modified to prepare the SEBS-polydopamine (PDA)-poly(lysine) quaternary ammonium derivative (PLQ) antibacterial surface by PDA deposition and surface grafting techniques to solve bacterial infections. PDA is used as an intermediate layer and presents an excellent photothermal effect. The grafted polymer PLQ has antimicrobial quaternary ammonium cation groups, which plays synergistic bactericidal therapy with PDA. The SEBS-PDA-PLQ surface almost totally suppresses the growth of bacteria with a surface bacterial survival rate of 0.05% under laser irradiation. The outstanding antibacterial activity of the SEBS-PDA-PLQ surface is attributed to the synergistic effects of the photothermal performance of PDA and quaternary ammonium cationic functional groups of PLQ. In addition, the membrane SEBS-PDA-PLQ shows good hydrophilicity, antiprotein adsorption ability, chemical stability, and biocompatibility. This antibiotic-free antimicrobial approach has great potential for practical application in solving infections associated with medical devices.

Facile Fabrication of Energetic Nanocomposite Materials by Polydopamine

Polydopamine-based materials have been widely investigated for incorporation in energetic nanocomposites due to their outstanding adherence. However, these materials are often prepared in alkaline environments, which negatively affects Al nanoparticles. In this study, a one-pot assembly was devised for the preparation of a polydopamine-based Al/CuO energetic nanocomposite material (Al/PDA/CuO) in a neutral environment. The CuO and Al nanoparticles of the Al/PDA/CuO nanothermite were uniformly dispersed and closely combined. Consequently, the Al/PDA/CuO nanothermite was able to release more heat (2069.7 J/g) than physically mixed Al/CuO (1438.9 J/g). Furthermore, the universality of using polydopamine in the assembly of different types of energetic nanocomposite materials was verified, including an organic energetic material-nanothermit (HMX/PDA/Al/CuO nanothermite) and an inorganic oxidant-metal nanocatalyst (AP/PDA/Fe2O3). This study provides a promising route for the preparation of polydopamine-based energetic nanocomposites in neutral aqueous solutions.

Copper Nanowire/Polydopamine-Modified Sodium Alginate Composite Films with Enhanced Long-Term Stability and Adhesion for Flexible Organic Light-Emitting Diodes

Copper nanowire (CuNW), with combined advantages of high conductivity and cost-effectiveness, is considered a promising material for the development of next-generation transparent conductive films (TCFs) in the field of flexible optoelectronics. However, the practical application of CuNW TCFs is hindered by some limitations, such as conductivity degradation and poor adhesion. Here, we demonstrate a stable CuNW composite film by embedding CuNWs into a polydopamine (PDA)-modified sodium alginate (NaAlg) matrix without sacrificing the optoelectronic properties of the CuNW network. The introduction of the PDA modifier significantly enhances the antiaging capability of the NaAlg layer, providing strengthened protection of the embedded CuNWs against moisture and oxygen, thereby resulting in minimal degradation of the conductivity of CuNWs for up to 9 months under ambient conditions. Simultaneously, the interface adhesion between the CuNW network and the substrate is further enhanced due to the abundance of catechol structures in PDA, allowing for the maintenance of the electrical conductivity of the CuNW network even under cyclic external bending stress and tape-peeling forces. In addition, embedding CuNWs into the polymer binding layer produces a CuNW composite film with a very smooth surface. A flexible OLED based on the PDA-modified NaAlg/CuNW TCF is successfully fabricated, exhibiting performance comparable to that of a traditional rigid indium tin oxide-based device, while also demonstrating remarkable mechanical durability. The modification strategy can promote practical applications of the CuNW network in flexible optoelectronic devices.

Laser-Induced Graphitization of Polydopamine on Titania Nanotubes

Since the discovery of laser-induced graphite/graphene, there has been a notable surge of scientific interest in advancing diverse methodologies for their synthesis and applications. This study focuses on the utilization of a pulsed Nd:YAG laser to achieve graphitization of polydopamine (PDA) deposited on the surface of titania nanotubes. The partial graphitization is corroborated through Raman and XPS spectroscopies and supported by water contact angle, nanomechanical, and electrochemical measurements. Reactive molecular dynamics simulations confirm the possibility of graphitization in the nanosecond time scale with the evolution of NH3, H2O, and CO2 gases. A thorough exploration of the lasing parameter space (wavelength, pulse energy, and number of pulses) was conducted with the aim of improving either electrochemical activity or photocurrent generation. Whereas the 532 nm laser pulses interacted mostly with the PDA coating, the 365 nm pulses were absorbed by both PDA and the substrate nanotubes, leading to a higher graphitization degree. The majority of the photocurrent and quantum efficiency enhancement is observed in the visible light between 400 and 550 nm. The proposed composite is applied as a photoelectrochemical (PEC) sensor of serotonin in nanomolar concentrations. Because of the suppressed recombination and facilitated charge transfer caused by the laser graphitization, the proposed composite exhibits significantly enhanced PEC performance. In the sensing application, it showed superior sensitivity and a limit of detection competitive with nonprecious metal materials.

Superoxide Dismutase-Like Regulated Fe/Ppa@PDA/B for Synergistically Targeting Ferroptosis/Apoptosis to Enhance Anti-Tumor Efficacy

The cell apoptosis pathway of sonodynamic therapy (SDT) is usually blocked, resulting in limited therapeutic efficacy, therefore, the development of new methods for sensitizing targeted ferroptosis and promoting apoptosis is of great significance to improve the anti-tumor efficacy of SDT. Herein, mesoporous Fe3 O4 nanoparticles (NPs) are synthesized for loading pyropheophorbide-a (ppa), surface-coated by polydopamine (PDA) and further anchored with tumor-targeting moieties of biotin to obtain Fe/ppa@PDA/B NPs. Fe/ppa@PDA/B displayes pH/ultrasound (US) responsive release properties, and magnetic resonance imaging (MRI) functions. Moreover, Fe3 O4 NPs of Fe/ppa@PDA/B as the Fe source for ferroptosis, enhances ferroptosis sensitivity by consuming glutathione (GSH) and producing hydroxyl radical (OH). The quinone groups of PDA layer on Fe/ppa@PDA/B own free electrons, which led to effective superoxide dismutase (SOD) action through superoxide anion (O2 - ) disproportionation to hydrogen peroxide (H2 O2 ) and oxygen (O2 ), thus, overcame hypoxia of SDT and promoted ·OH generation by Fe ions under US trigger, synergistically improves ferroptosis and apoptosis to enhance the anti-tumor efficacy of SDT both in vitro and in vivo. The anti-tumor strategy of synergistic apoptosis and ferroptosis induce by GSH depletion and self-sufficient O2 regulated by SOD provides a new idea for enhancing SDT efficacy.

Polydopamine-Based Nanoprobes Application in Optical Biosensing

Polydopamine (PDA), the synthetic counterpart of melanin, is a widely investigated bio-inspired material for its chemical and photophysical properties, and in the last few years, bio-application of PDA and PDA-based materials have had a dramatic increase. In this review, we described PDA application in optical biosensing, exploring its multiple roles as a nanomaterial. In optical sensing, PDA can not only be used for its intrinsic fluorescent and photoacoustic properties as a probe: in some cases, a sample optical signal can be derived by melanin generation in situ or it can be enhanced in another material thanks to PDA modification. The various possibilities of PDA use coupled with its biocompatibility will indeed widen even more its application in optical bioimaging.

Polydopamine-curcumin coating of titanium for remarkable antibacterial activity via synergistic photodynamic and photothermal properties

Combined photothermal therapy (PTT) and photodynamic therapy (PDT) has emerged as a novel and effective antibacterial strategy. In order to endow titanium (Ti) with antibacterial properties, the Ti-PDA-Cur composite was prepared using the excellent adhesion properties of polydopamine (PDA) to load curcumin (Cur) on the surface of Ti. The Ti-PDA-Cur coating can produce singlet oxygen (1 O2 ) and heat under 405 + 808 nm light irradiation, which can effectively kill Staphylococcus aureus and Escherichia coli. Moreover, the cytotoxicity and hemolysis rate of Ti-PDA-Cur were low, indicating its good biocompatibility. Therefore, this study provided a new strategy for the development of new Ti implants.

N-Type Coating of Single-Walled Carbon Nanotubes by Polydopamine-Mediated Nickel Metallization

Single-walled carbon nanotubes (SWCNTs) have unique thermal and electrical properties. Coating them with a thin metal layer can provide promising materials for many applications. This study presents a bio-inspired, environmentally friendly technique for CNT metallization using polydopamine (PDA) as an adhesion promoter, followed by electroless plating with nickel. To improve the dispersion in the aqueous reaction baths, part of the SWCNTs was oxidized prior to PDA coating. The SWCNTs were studied before and after PDA deposition and metallization by scanning and transmission electron microscopy, scanning force microscopy, and X-ray photoelectron spectroscopy. These methods verified the successful coating and revealed that the distribution of PDA and nickel was significantly improved by the prior oxidation step. Thermoelectric characterization showed that the PDA layer acted as a p-dopant, increasing the Seebeck coefficient S of the SWCNTs. The subsequent metallization decreased S, but no negative S-values were reached. Both coatings affected the volume conductivity and the power factor, too. Thus, electroless metallization of oxidized and PDA-coated SWCNTs is a suitable method to create a homogeneous metal layer and to adjust their conduction type, but more work is necessary to optimize the thermoelectric properties.