PDA NPs Research Articles

NIR Responsive Drug Cocktail Using J‐Aggregates of Indocyanine Green Loaded Polydopamine Nanoparticles for Chemo‐Phototherapy of Cancer

AbstractCo‐loading of drugs/dyes onto nanoparticles is a widely adapted strategy to achieve synergistic/combinatorial effects. However, one of the co‐loaded drugs may show dominant loading which reduces the loading efficiency of the other depending on the properties of the drug/dye loaded. Cisplatin (CDDP), a potent chemotherapeutic drug has very limited usage because of its poor aqueous solubility and systemic toxicity. A novel J‐aggregate is formulated using indocyanine green (ICG) and CDDP called the ICG J‐aggregate (IJA) which coordinates CDDP with ICG and enhances its water solubility resulting in higher loading. Further, polydopamine nanoparticles (PDA NPs) are used, which has shown excellent loading efficiency of IJA to form P‐IJA nano formulation. The results for the first time provide evidence of 2–4 folds increase in CDDP's loading in IJA formulation in comparison to loading of free CDDP under the same conditions. The overall P‐IJA formulation is capable of multi‐modal cancer therapy, i.e., chemotherapy, photothermal therapy, photodynamic therapy, and ferroptosis‐like selective cancer killing. The formulated P‐IJA is also found to be biocompatible, hemocompatible, and stable. The finding of the study suggests that P‐IJA can be effectively activated under NIR laser/pH as stimuli for deep‐tissue synergistic therapy.

Synergistic antibacterial attributes of copper-doped polydopamine nanoparticles: an insight into photothermal enhanced antibacterial efficacy

Antibiotic-resistant bacteria and associated infectious diseases pose a grave threat to human health. The antibacterial activity of metal nanoparticles has been extensively utilized in several biomedical applications, showing that they can effectively inhibit the growth of various bacteria. In this research, copper-doped polydopamine nanoparticles (Cu@PDA NPs) were synthesized through an economical process employing deionized water and ethanol as a solvent. By harnessing the high photothermal conversion efficiency of polydopamine nanoparticles (PDA NPs) and the inherent antibacterial attributes of copper ions, we engineered nanoparticles with enhanced antibacterial characteristics. Cu@PDA NPs exhibited a rougher surface and a higher zeta potential in comparison to PDA NPs, and both demonstrated remarkable photothermal conversion efficiency. Comprehensive antibacterial evaluations substantiated the superior efficacy of Cu@PDA NPs attributable to their copper content. These readily prepared nano-antibacterial materials exhibit substantial potential in infection prevention and treatment, owing to their synergistic combination of photothermal and spectral antibacterial features.

Controlled Nitric Oxide-Releasing Nanovehicles for Enhanced Infected Wound Healing: A Study on PDA@BNN6 Encapsulated in GelMA Hydrogel.

The photo-activated thermo/gas antimicrobial nanocomposite hydrogel, Gel/PDA@BNN6, is composed of the nitric oxide (NO) carrier N, N'-di-sec-butyl-N, N'-dinitroso-p-phenylenediamine (BNN6), photothermal (PTT) material polydopamine nanoparticles (PDA NPs), and methacrylate gelatin (GelMA). This hydrogel can release NO gas in a stable and controlled manner, generating a localized photothermal effect when exposed to near-infrared laser light. This dual action promotes the healing of full-thickness skin wounds that are infected. Gel/PDA@BNN6 was developed, and both in vitro and in vivo experiments were carried out to evaluate its structure, physicochemical properties, antibacterial effects, effectiveness in promoting infected wound healing, and biocompatibility. Gel/PDA@BNN6 was successfully synthesized, exhibiting a porous three-dimensional lattice structure and excellent mechanical properties. It demonstrated highly efficient photothermal conversion, controllable nitric oxide delivery, strong bactericidal effects, and minimal cytotoxicity in vitro. In vivo, Gel/PDA@BNN6, when used with NIR therapy, showed significant anti-inflammatory effects, promoted collagen deposition, and stimulated vascular neoangiogenesis, which accelerated wound closure. Additionally, it displayed superior biocompatibility. Gel/PDA@BNN6has shown an explicit curative effect for infected wound healing, suggesting it has a good chance of being an antimicrobial dressing in the future.

A novel nanoprobe for visually investigating the controversial role of miRNA-34a as an oncogene or tumor suppressor in cancer cells.

MiRNA-targeted therapy has become a hot topic in current cancer research. The key to this treatment strategy is to clarify the specific role of miRNA in cancer. However, the roles of some miRNAs acting as oncogenic or tumor suppressors are still controversial, which are influenced by different tumor types, even in the same cancer type. Hence, we designed a novel fluorescent nanoprobe based on polydopamine nanoparticles (PDA NPs) for simultaneously detecting caspase-3 and miRNA-34a within living cells. The specific role of miRNA-34a in different cancer cells could be further identified by studying the expression alterations of caspase-3 and miRNA-34a. Confocal imaging indicated that miRNA-34a indeed acted as a tumor suppressor in anticancer drug-treated MCF-7 and HeLa cells, where the effect of miRNA-34a remains controversial. The designed nanoprobe can offer a promising approach to ascertain the oncogenic or tumor-suppressing role of miRNA in different cancer cells with a simple visualization method, which has valuable implications for exploring the practicability of precision therapy focused on miRNA and evaluating the efficacy of new miRNA-targeted anticancer medications.

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.

Synthesis of polyelectrolyte-decorated polydopamine nanoparticles via surface reconstruction for enhancing oil-based lubrication

Polydopamine nanoparticles (PDA NPs) show bright prospects in the field of lubricant additives due to their high interface adhesion and reaction properties. However, the synthesis of PDA NPs with excellent dispersibility and lubricity in lubricating oils remains a great challenge. In this work, a class of polyelectrolyte-decorated PDA NPs (PPDA NPs) were synthesized by surface reconstruction of PDA NPs. The lipophilic PPDA NPs can be stabilized in PEG200 base oil without any sediments over 6 months. Compared with PEG200 base oil, the PPDA NPs (1.0 wt%)/PEG200 dispersion not only reduced the friction coefficient (COF) by 37.3 % and wear volume by 51.6 % but also performed well under heavy loads, high speeds, and long duration. Wear surface analyses confirmed that the structural evolution from PPDA NPs to nanosheets induced the formation and deposition of hybrid tribofilm with robust tribological behaviors, enabling desirable oil lubrication. Overall, the synergistic effects between PDA cores and PPDA shells contributed to the superior lubricity of PPDA NPs. This study provides a promising protocol for designing and synthesizing oil-dispersible PPDA NPs, brightening the application prospect of organic polymer NPs in tribology.

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

Aim: This study focused on treating periodontitis with bacterial infection and local overaccumulation ofreactive oxygen species. Materials & methods: Polydopamine nanoparticles (PDA NPs) were exploited asefficient carriers for encapsulated metronidazole (MNZ). The therapeutic efficacy and biocompatibilityof PDA@MNZ NPs were investigated through both in vitro and in vivo studies. Results: The nanodrugPDA@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 growthof Porphyromonas gingivalis. Moreover, the PDA@MNZ NPs exhibited synergistic therapy for periodontitisin invivo. Conclusion: PDA@MNZ NPs were confirmed with exceptional antimicrobial and antioxidantfunctions, offering a promising avenue for synergistic therapy in periodontitis.

An Integrated Quorum Quenching Biocatalytic Nanoplatform for Synergistic Chemo-Photothermal Eradication of P. aeruginosa Biofilm Infections.

Decontamination of biofilm-associated infections presents a significant challenge due to the physical and chemical barrier created by the formation of extracellular matrices. This barrier restricts the access of antibiotics to the bacterial communities within the biofilm and provides protection to the persister cells, potentially leading to antibiotic resistance. In this study, we have developed an integrated quorum quenching biocatalytic nanoplatform for the synergistic chemo-photothermal eradication of P. aeruginosa biofilm infections. Ciprofloxacin (Cip), a model antibiotic, was absorbed onto PDA NPs through π-π stacking. Additionally, acylase (AC) was immobilized on PDA NPs through Schiff base reaction and Michael addition, resulting in the formation of the biocatalytic nanoplatform (PDA-Cip-AC NPs). This biocatalytic nanoplatform was able to enzymatically degrade AHL signaling molecules, thus achieving efficient quorum quenching activity to prevent biofilm formation. Furthermore, the NIR light-triggered on-demand Ciprofloxacin release further enhanced the eradication of P. aeruginosa biofilm infections with a synergy of local hyperthermia. We envision that this integrated quorum quenching nanoplatform provides a reliable tool for combating P. aeruginosa biofilm infections. STATEMENT OF SIGNIFICANCE: : An integrated quorum quenching biocatalytic nanoplatform has been developed for the eradication of P. aeruginosa biofilm infections. Quorum-sensing signals play a crucial role in modulating bacterial cell-to-cell communication, biofilm formation, and secretion of virulence factors. This biocatalytic nanoplatform efficiently degrades AHL signaling molecules, thereby blocking cell-to-cell communication and preventing biofilm formation. Additionally, local hyperthermia and on-demand Ciprofloxacin release were achieved through NIR irradiation, working synergistically to eradicate P. aeruginosa biofilm infections.

High extinction coefficient material combined with multi-line lateral flow immunoassay strip for ultrasensitive detection of bacteria.

Lateral flow immunoassay strips (LFIAs) are a reliable and point-of-care detection method for rapid monitoring of bacteria, but their sensitivity was limited by the low extinction coefficient of colloidal gold nanoparticles (Au NPs) and low capture efficiency of test-line. In this study, polydopamine nanoparticles (PDA NPs) were employed to replace Au NPs, due to their high extinction coefficient. And the amount of test-line was increased to 5 for further improving the efficiency of bacteria capture. Thus, under visual observation, the detection limits of PDA-based LFIAs (102 CFU/mL) were about 2 orders of magnitude lower than Au-based LFIAs (104 CFU/mL). Furthermore, the invisible signal could be collected by Image J and the detection limit can reach 10CFU/mL. The proposed test strips were successfully applied for the quantitative, accurate, and rapid screening of E. coli in food samples. This study provided a universal approach to enhance the sensitivity of bacteria LFIAs.

A Photothermal Therapy Study Based on Electrospinning Nanofibers Blended and Coated with Polydopamine Nanoparticles

AbstractThe development of high‐efficiency and good biocompatible photothermal therapy platforms is conducive to avoiding the risks of nano‐preparations in vivo. The poly‐L‐lactic acid (PLLA) indicated good biodegradability and biocompatibility. Inspired by natural melanin and the extraordinary nontoxic mussel biopolymer, polydopamine nanoparticles (PDA NPs) with photothermal efficacy have attracted increasing attention. Herein, we performed the study of blended PDA/PLLA and coated PDA@PLLA electrospun nanofibers (ESNFs) for photothermal therapy. In photothermal experiment, the PDA@PLLA ESNF displayed higher light‐to‐heat conversion and photothermal stability than that of PDA/PLLA and PLLA ESNF. Both in vitro and in vivo experiments tested that three kinds of ESNF exhibited low toxicity and outstanding biocompatibility. Moreover, the PDA@PLLA ESNF showed better property for the cell proliferation due to the rough surface and good hydrophilicity. The in vivo photothermal potentiality of the PLLA, PDA/PLA and PDA@PLLA ESNF was evaluated in nude mice of inoculating the tumor, in which the PDA/PLA and PDA@PLLA ESNF significantly inhibited the tumor increasing compared to control group. Especially, the PDA@PLLA ESNF showed better photothermal therapy, which made the tumor irreversible ablate at local tumor tissue. These results stand out the usage of PDA@PLLA ESNF as potential photothermal therapy material.

Synthesis and characterization of pH-triggered doxorubicin-conjugated polydopamine-coated cobalt ferrite nanoparticles for in-vitro/in-vivo studies in liver cancer therapy

Polydopamine-coated cobalt ferrite nanoparticles (PDA-coated CF-NPs) were synthesized and characterized for their potential in drug delivery evaluation. Small-angle X-ray scattering (SAXS) showed post-coating spherical shape of magnetic PDA NPs. The scattering intensity at zero angle (I(0)) of PDA-coated CF (0.01) had higher scattering intensity than CF-NPs (0.49 × 10-3). PDA increased the flexibility degree of unfolding on Kratky plot shifting from 1.05 to 1.87 at same qRg values. The pair-distance distribution function (P(r)) of PDA-coated CF-NPs indicated a more homogeneous and compact scattering structure. GNOM indicated larger size for CF, while PDA-coated CF (a narrower and taller peak) displayed a more compact and uniform scattering profile. PDA reduced crystallinity size to 2.51 nm with amorphous peaks at 38.12°, 44.28°, and 64.43° degree and infrared spectrum confirmed PDA incorporation onto CF-NPs. PDA-coated CF had 1.5-fold larger pore size and enhanced surface area. CF and PDA-coated CF exhibited “S” shape behavior in Langevin function without hysteresis. The kinetic models suggested Fickian diffusion and sustainable release for the erosion-dominated release of the PDA-coated CF. In vitro, doxorubicin (DOX)-carried PDA-coated CF (D-P@CF) showed low toxicity to HepG2 cells; in vivo, liver tumor inhibition indicated medication delivery potential for cancer treatment.

Multifunctional hemostatic polysaccharide-based sponge enhanced by tunicate cellulose: A promising approach for photothermal antibacterial activity and accelerated wound healing

Fast and effective hemostasis and protection against wound infection play a crucial role in trauma care. In this study, a sponge scaffold with a self-expanding interpenetrating macropore structure was designed via two-step cross-linking method for hemostasis and photothermal antimicrobial activity. Oxidized Konjac glucomannan (OKGM) and chitosan (CS) were crosslinked once to form a dynamic covalent bonding network, and a basic three-dimensional fiber porous network framework was constructed by uniformly dispersing Tunicate nanocellulose (TCNCs). Secondary crosslinking introduced Polydopamine (PDA NPs) into the sponge, while dynamic hydrogen bonds were interleaved to stabilize the frame. PDA NPs enhanced the sponge's antibacterial and antioxidant properties due to its good photothermal conversion efficiency and oxygen radical scavenging ability. Compared to cotton gauze and gelatin sponges, the composite sponges showed superior blood cell adhesion and platelet activation. In tests on rat liver trauma models, composite sponges showed shorter hemostasis time (12 ± 2.17 s) and less blood loss (0.1 ± 0.052 g). Sponges can protect wound tissue through their adhesion properties. In the full-thickness wound model infected with S. aureus, the composite sponge accelerated wound healing. Overall, this composite sponge has great potential for clinical use as a wound dressing.

Cellulose-Based Photothermal Coating: A Sustainable Solution for Seed Protection and Long-Term Grain Storage.

High-output modern agriculture based on synthetic chemicals (biocides, pesticides, and fertilizers) feeds the growing global population. To completely abandon the use of pesticides and fertilizers will undoubtedly cause a severe food crisis worldwide, and sustainable alternative solutions are urgently demanded to stop biocides and fertilizers overuse. Herein, a versatile and green strategy is proposed for seed protection and long-term storage of grains using a cellulose-based photothermal coating (PDA NPs@Cell-N+) that consists of photothermal polydopamine nanoparticles (PDA NPs) and a positive-charged cellulose derivative (Cell-N+) to eradicate seed-borne bacteria and fungi simply under infrared irradiation. In vitro and in vivo assays and the seedling-stage phenotypes of mung bean (Vigna radiata) suggest that pathogenic microbes, including the tough Aspergillus flavus (inhibition ratio >99%), can be efficiently eliminated by photothermal therapy. Thus, the seed-borne diseases of mung beans can finally be prevented. Owing to excellent solubility and biocompatibility, the PDA NPs@Cell-N+ coating can be washed off and recycled without food safety concerns. PDA NPs@Cell-N+ can be a nature-based solution for seed protection and long-term grain storage.

Dual stimuli-responsive gelatin-based hydrogel for pH and temperature-sensitive delivery of curcumin anticancer drug

Stimuli-sensitive drug delivery enables transporting therapeutic agents to diseased areas and then releasing their cargo in response to external or internal stimuli. Here, we report on the synthesis and characterization of dual stimuli-responsive hydrogel for pH and temperature-sensitive delivery of curcumin (CUR) anticancer drug. CUR-loaded chitosan nanocapsules (CURNCs) were embedded in glucose-crosslinked gelatin hydrogel containing polydopamine nanoparticles (PDA NPs) (denoted as GGPDNCs). The result showed that CUR release from CURNCs was higher at acidic pH values. Glucose-crosslinked gelatin hydrogel was stable at 37 °C. To enable thermal responsivity under NIR laser irradiation, PDA NPs were embedded in the glucose-crosslinked gelatin hydrogel. The GGPDNCs hydrogel is, thus, engineered to respond to both pH and temperature stimuli. Under the optimum conditions, the release of CUR from the GGPDNCs-hydrogel under NIR irradiation (940 nm, 1.5 W/cm2) at pH = 5.0 was 1.43-fold higher than pH = 7.4 which is a promising progress in smart drug delivery systems for cancer therapy.

Iron ion and siramesine-loaded polydopamine nanoparticles forenhanced breast cancer therapy

Ferroptosis is a novel type of nonapoptotic cell death, showing a hopeful potential in cancer therapeutic schedules. Oneof the apparent features of ferroptosis is the lipid hydroperoxides producing ROS induced by intracellular iron ionsaccumulation. Thus the iron regulation and metabolism in the cell is an essential factors for the trigger of ferroptosis.We designed a new nanoparticle that loaded ferric ions and siamese based on polydopamine nanomaterial (siramesine@Fe(III) PDA NPs) to induce breast cancer ferroptosis through the Fenton reaction. Iron ions can be added to cancer cells,and siamese can block the exportation of intracellular iron by inhibiting the expression of FPN, thus promoting theFenton reaction. The extra transport of iron ions into cells by nanoparticles and the inhibition of iron ions outward bySiramesine promoted the accumulation of iron ions in cells, thus achieving a synergistic effect leading to ferroptosis incells. In addition, NPs demonstrated excellent pH-responsive degradation, with enhanced drug release at the pH valueof tumor microenvironments and lysosomal. Siramesine@Fe(III) PDA NPs showed good ferroptosis induction ability,displaying the potential for cancer treatment.

Mannosylated polydopamine nanoparticles alleviate radiation- induced pulmonary fibrosis by targeting M2 macrophages and inhibiting the TGF-β1/Smad3 signaling pathway

Radiation-induced pulmonary fibrosis (RIPF), one type of pulmonary interstitial diseases, is frequently observed following radiation therapy for chest cancer or accidental radiation exposure. Current treatments against RIPF frequently fail to target lung effectively and the inhalation therapy is hard to penetrate airway mucus. Therefore, this study synthesized mannosylated polydopamine nanoparticles (MPDA NPs) through one-pot method to treat RIPF. Mannose was devised to target M2 macrophages in the lung through CD 206 receptor. MPDA NPs showed higher efficiency of penetrating mucus, cellular uptake and ROS-scavenging than original polydopamine nanoparticles (PDA NPs) in vitro. In RIPF mice, aerosol administration of MPDA NPs significantly alleviated the inflammatory, collagen deposition and fibrosis. The western blot analysis demonstrated that MPDA NPs inhibited TGF-β1/Smad3 signaling pathway against pulmonary fibrosis. Taken together this study provide a novel M2 macrophages-targeting nanodrugs through aerosol delivery for the prevention and targeted treatment for RIPF.

Polydopamine Nanoparticles-Based Photothermal Effect Against Adhesion Formation in a Rat Model of Achilles Tendon Laceration Repair.

Adhesion formation after tendon surgery is a major obstacle to repair of tendon ruptures, and there is still no effective clinical anti-adhesion method. Myofibroblasts expressing α-smooth muscle actin (α-SMA) play a crucial role in adhered fibrous tissue. Heat shock protein (Hsp) 72 can selectively prevent the activation of c-Jun N-terminal kinase (JNK), which mediates the conversion from fibroblasts to myofibroblasts. The purpose of this study was to investigate for the first time whether polydopamine nanoparticles (PDA NPs)-based photothermal effect would attenuate adhesion formation in a rat model of Achilles tendon laceration repair. Forty-five adult male Sprague-Dawley rats were randomly assigned to the photothermal group, the control group and the PDA NPs group (n = 15 per group). The primary outcome measure was the adhesion scores at two weeks after surgery according to the grading of Tang et al. The secondary outcomes included the expressions of Hsp 72, JNK, phosphorylated JNK and α-SMA, which were measured by immunohistochemistry or Western blot. The average adhesion score was significantly lower in the photothermal group (4.25 ± 0.21) than that in the control group (5.29 ± 0.12) (p = 0.005) and the PDA NPs group (5.29 ± 0.20) (p = 0.005). Relative to the control group and PDA NPs group, Hsp 72 in the photothermal group was significantly increased whereas α-SMA and p-JNK was significantly decreased, but JNK was not found to be different across the three groups. The photothermal effect produced by PDA NPs could reduce tendon adhesion formation in rats by inhibiting myocyte fibrosis, which may have potential in developing endogenous heating for postsurgical tissue adhesions.

Applications of photothermally mediated nanohybrids for white spot lesions in orthodontics

In orthodontic treatment, cariogenic bacteria in the oral cavity are the main cause of enamel white spot lesions (WSLs). Therefore, to effectively prevent and treat WSLs, it is crucial to inhibit the cariogenic bacterial activity while promoting the remineralization of demineralized tooth enamel. However, fluoride preparations commonly used for the prevention and treatment of WSLs can induce dental fluorosis if ingested in excess, and their remineralization effect is limited by the residual hydroxyapatite (HAp) content and salivary Ca2+ and PO43- levels. In this study, we propose a strategy (CMCS/ACP@PDA) for antibacterial and remineralization of WSLs by a nanohybrid of carboxymethyl chitosan (CMCS)-stabilized amorphous calcium phosphate (ACP) loaded polydopamine nanoparticles (PDA NPs) based on biomimetic remineralization techniques and biocompatible near-infrared (NIR) photoactivation therapy. The nanohybrid utilizes the excellent photothermal conversion ability of polydopamine for antimicrobial purposes, while CMCS with its own positive and negative charges (-NH3+ and -COO-) acts as a biomimetic mineralizing agent to stabilize ACP, supplemented with abundant Ca2+ and PO43- for remineralization of demineralized enamel. The results showed that CMCS/ACP@PDA could effectively inhibit the adhesion of cariogenic Streptococcus mutants (S. mutants) with high bactericidal rates. In addition, the remineralization of demineralized enamel by nanohybrid was more effective after 7 days of in vitro mineralization. This study provides a theoretical and experimental basis for the use of CMCS/ACP@PDA nanohybrid materials as potential materials against WSLs.

Polydopamine nanoparticles coated with a metal-polyphenol network for enhanced photothermal/chemodynamic cancer combination therapy

Polydopamine nanoparticles (PDA NPs) are commonly used for photothermal therapy (PTT) of cancer because of their good biocompatibility and photothermal conversion capability. However, it is difficult to achieve a good tumor inhibition effect with a single PTT of PDA. Therefore, in this work, we prepared a combined anticancer nanosystem for enhanced chemodynamic therapy (CDT)/PTT by coating PDAs with an (−)-epigallocatechin gallate (EGCG)/iron (Fe) metal-polyphenol network (MPN). The MPN shell of this nanosystem named EGCG@PDA is degraded by the weakly acidic environment intracellular, releasing EGCG and Fe3+. EGCG inhibits the expression of heat shock proteins (HSPs) in cancer cells, thus eliminating their thermal protection against cancer cells for enhanced PTT. Meanwhile, the reductive EGCG can also reduce Fe3+ to Fe2+, to catalyze the decomposition of overexpressed hydrogen peroxide (H2O2) in cancer cells to generate strong oxidative hydroxyl radicals (OH), i.e., catalyzing the Fenton reaction, for CDT. After the Fenton reaction, the re-oxidized Fe ions can be reduced again by EGCG and reused to catalyze the Fenton reaction, which can achieve enhanced CDT. Both in vitro and in vivo studies have shown that EGCG@PDA has low dark toxicity and good anticancer effects. It is expected to be used for precision cancer therapy.

Melanin-like polydopamine nanoparticles mediating anti-inflammatory and rescuing synaptic loss for inflammatory depression therapy

Inflammatory depression is closely related to neuroinflammation. However, current anti-inflammatory drugs have low permeability to cross blood–brain barrier with difficulties reaching the central nervous system to provide therapeutic effectiveness. To overcome this limitation, the nano-based drug delivery technology was used to synthesize melanin-like polydopamine nanoparticles (PDA NPs) (~ 250 nm) which can cross the blood–brain barrier. Importantly, PDA NPs with abundant phenolic hydroxyl groups function as excellent free radical scavengers to attenuate cell damage caused by reactive oxygen species or acute inflammation. In vitro experiments revealed that PDA NPs exhibited excellent antioxidative properties. Next, we aimed to investigate the therapeutic effect of PDA NPs on inflammatory depression through intraperitoneal injection to the lipopolysaccharide-induced inflammatory depression model in mice. PDA NPs significantly reversed the depression-like behavior. PDA NPs was also found to reduce the peripheral and central inflammation induced by LPS, showing that alleviated splenomegaly, reduced serum inflammatory cytokines, inhibited microglial activation and restored synaptic loss. Various experiments also showed that PDA NPs had good biocompatibility both in vivo and in vitro. Our work suggested that PDA NPs may be biocompatible nano-drugs in treating inflammatory depression but their clinical application requires further study.Graphical