Zinc hexacyanoferrate/g-C3N4 nanocomposites with enhanced photothermal and photodynamic properties for rapid sterilization and wound healing.

Photoactivated therapy has gradually emerged as a promising and rapid method for combating bacteria, aimed at overcoming the emergence of drug-resistant strains resulting from the inappropriate use of antibiotics and the subsequent health risks. In this work, we report the facile fabrication of Zn3[Fe(CN)6]/g-C3N4 nanocomposites (denoted as ZHF/g-C3N4) through the in-situ loading of zinc hexacyanoferrate nanospheres onto two-dimensional g-C3N4 sheets using a simple metal-organic frameworks construction method. The ZHF/g-C3N4 nanocomposite exhibits enhanced antibacterial activity through the synergistic combination of the excellent photothermal properties of ZHF and the photodynamic capabilities of g-C3N4. Under dual-light irradiation (420 nm + 808 nm NIR), the nanocomposites achieve remarkable bactericidal efficacy, eliminating 99.98% of Escherichia coli and 99.87% of Staphylococcus aureus within 10 minutes. Furthermore, in vivo animal experiments have demonstrated the outstanding capacity of the composite in promoting infected wound healing, achieving a remarkable wound closure rate of 99.22% after a 10-day treatment period. This study emphasizes the potential of the ZHF/g-C3N4 nanocomposite in effective antimicrobial applications, expanding the scope of synergistic photothermal/photodynamic therapy strategies.

Cobalt doped Prussian blue modified hollow polydopamine for enhanced antibacterial therapy.

Give the emergence of drug resistance in bacteria resulting from antibiotic misuse, there is an urgent need for research and application of novel antibacterial approaches. In recent years, nanoparticles (NPs) have garnered significant attention due to their potential to disrupt bacteria cellular structure through loading drugs and special mechanisms, thus rendering them inactive. In this study, the surface of hollow polydopamine (HPDA) NPs was utilized for the growth of Prussian blue (PB), resulting in the formation of HPDA-PB NPs. Incorporation of Co element during the preparation process led to partial doping of PB with Co2+ions. The performance test results demonstrated that the HPDA-PB NPs exhibited superior photothermal conversion efficiency and peroxidase-like activity compared to PB NPs. HPDA-PB NPs have the ability to catalyze the formation of hydroxyl radicals from H2O2in a weakly acidic environment. Due to the tiny PB particles on the surface and the presence of Co2+doping, they have strong broad-spectrum antibacterial properties. Bothin vitroandin vivoevaluations confirm their efficacy against various bacterial strains, particularlyStaphylococcus aureus, and their potential to promote wound healing, making them a promising candidate for advanced wound care and antimicrobial applications.

Dental Caries Management with Antibacterial Silver-Doped Prussian Blue Hydrogel by the Combined Effects of Photothermal Response and Ion Discharge.

Caries is a destructive condition caused by bacterial infection that affects the hard tissues of the teeth, significantly reducing the quality of life for individuals. Photothermal therapy (PTT) offers a noninvasive and painless treatment for caries, but the use of unsafe laser irradiance limits its application. To address this challenge, we prepared nanoparticles of silver ion-doped Prussian blue (AgPB), which was encased within cationic guar gum (CG) to form the antibacterial PTT hydrogel CG-AgPB with a photothermal conversion efficiency of 34.4%. When exposed to an 808 nm laser at a power density of 0.4 W/cm2, the hydrogel readily reached a temperature of over 50 °C in just 3 min, synchronized by the discharge of Ag+ ions from the interstitial sites of AgPB crystals, resulting in broad-spectrum and synergistic antibacterial activities (>99%) against individual oral pathogens (Streptococcus sanguinis, Streptococcus mutans, and Streptococcus sobrinus) and pathogen-induced biofilms. In vivo, CG-AgPB-mediated PTT demonstrated a capability to profoundly reduce the terminal number of cariogenic bacteria to below 1% in a rat model of caries. Given the outstanding biocompatibility, injectability, and flushability, this CG-AgPB hydrogel may hold promise as a next-generation oral hygiene adjunct for caries management in a clinical setting.

Balancing Bioresponsive Biofilm Eradication and Guided Tissue Repair via Pro-Efferocytosis and Bidirectional Pyroptosis Regulation during Implant Surgery.

There is an increasingly growing demand to balance tissue repair guidance and opportunistic infection (OI) inhibition in clinical implant surgery. Herein, we developed a nanoadjuvant for all-stage tissue repair guidance and biofilm-responsive OI eradication via in situ incorporating Cobaltiprotoporphyrin (CoPP) into Prussian blue (PB) to prepare PB-CoPP nanozymes (PCZs). Released CoPP possesses a pro-efferocytosis effect for eliminating apoptotic and progressing necrotic cells in tissue trauma, thus preventing secondary inflammation. Once OIs occur, PCZs with switchable nanocatalytic capacity can achieve bidirectional pyroptosis regulation. Once reaching the acidic biofilm microenvironment, PCZs possess peroxidase (POD)-like activity that can generate reactive oxygen species (ROS) to eradicate bacterial biofilms, especially when synergized with the photothermal effect. Furthermore, generated ROS can promote macrophage pyroptosis to secrete inflammatory cytokines and antimicrobial proteins for biofilm eradication in vivo. After eradicating the biofilm, PCZs possess catalase (CAT)-like activity in a neutral environment, which can scavenge ROS and inhibit macrophage pyroptosis, thereby improving the inflammatory microenvironment. Briefly, PCZs as nanoadjuvants feature the capability of all-stage tissue repair guidance and biofilm-responsive OI inhibition that can be routinely performed in all implant surgeries, providing a wide range of application prospects and commercial translational value.

Dermal extracellular matrix gelatin delivering Prussian blue nanoparticles to relieve skin flap ischemia.

The survival rate of flap is a crucial factor for determining the success of tissue repair and reconstruction. Flap transplantation surgery often leads to ischemic and reperfusion injury, causing apoptosis and tissue necrosis, which significantly reduces the survival rate of flap. To address this issue, we developed a porcine skin decellularized matrix gel nanocomplex loaded with alprostadil (Alp) in Prussian blue nanoparticles (PB NPs) called Alp@PB-Gel. This gel not only maintained the cell affinity of the extracellular scaffold but also exhibited a high degree of plasticity. In vitro assays demonstrated that Alp@PB-Gel possessed antioxidant activity, scavenging ROS ability, and effectively promoted the angiogenesis and migration of human vascular endothelial cells (HUVECs) by stimulating the proliferation of vascular epithelial cells and fibroblasts. In vivo assays further confirmed that Alp@PB-Gel could effectively alleviate necrosis in the early and late stages after surgery, downregulate the levels of NLRP3 and CD68 to inhibit apoptosis and attenuate inflammation, while upregulate the levels of VEGF and CD31 to promote vascular tissue regeneration. Moreover, Alp@PB-Gel exhibited excellent cell affinity and biocompatibility, highlighting its potential for clinical application.

Artificial nonenzymatic antioxidant Prussian blue/KGM-BSA nanocomposite hydrogel dressing as ROS scavenging for diabetic wound healing.

The process of diabetic wound healing was influenced by the excessive proliferation of reactive oxygen species (ROS). Therefore, in the process of healing diabetic wounds, it was crucial to removing ROS. This study designed composited nanoparticles: KBP, consisted by Konjac glucomannan, bovine serum albumin, and Prussian blue. Then they were embedded in Konjac glucomannan and hydroxypropyl trimethylammonium chloride chitosan composite hydrogel (KH), The KBP@KH hydrogel finally achieved excellent efficacy in diabetic wound healing. The in vitro and in vivo experiments demonstrated that KPB nanoparticles exhibited favorable ROS scavenging capability and biosafety. The KBP@KH hydrogel not only effectively eliminated ROS from diabetic wounds, but also exhibited excellent wound adaptability. The KBP@KH hydrogel facilitated angiogenesis and suppressed the production of inflammatory factors. Overall, the KBP@KH hydrogel dressing was characterized by its user-friendly nature, safety, and high efficiency.

In vitro and in vivo removal efficacy of insoluble Prussian blue in combination with calcium polystyrene sulfonate for thallium.

The similarities between thallium and potassium have suggested the use of calcium polystyrene sulfonate (CPS), an oral ion exchange resin, as a potential agent against thallium intoxication. Therefore, the study was an attempt to evaluate the efficacy of CPS and Prussian blue when given alone or in combination against thallium toxicity. The effect on binding capacity was investigated in terms of contact time, amount of CPS, influence of pH, simulated physiological solutions and interference of potassium ions. Also, rats were given single dose of thallium chloride (20 mg kg-1) and the treatment with PB and CPS was given for 28 days as CPS 30 g kg-1, orally, twice a day, PB 3 g kg-1, orally, twice a day and their combination. The effect of antidotal treatment was evaluated by calculating the thallium levels in various organs, blood, urine and feces. The results of the in vitro study indicated exceedingly quick binding in the combination of CPS and PB as compared to PB alone. Also, it was found that the binding capacity at pH 2.0 was considerably increased for PB with CPS (184.656 mg g-1) as compared to PB (37.771 mg g-1). Furthermore, statistically significant results were obtained in the in vivo study as after 7th day, thallium levels in blood of rats treated with combination were reduced by 64% as compared to control group and 52% as compared to alone PB treated group. Also, Tl retention in liver, kidney, stomach, colon and small intestine of combination treated rats was significantly reduced to 46%, 28%, 41%, 32% and 33% respectively, as compared to alone PB treated group. These findings demonstrate this as a good antidotal option against thallium intoxication.

Dual-inhibition of lactate metabolism and Prussian blue-mediated radical generation for enhanced chemodynamic therapy and antimetastatic effect.

Numerous research studies have proved that lactate is pivotal in tumor proliferation, metastasis, and recurrence, so disrupting the lactate metabolism in the tumor microenvironment (TME) has become one of the effective methods of tumor treatment. Herein, we have developed a versatile nanoparticle (HCLP NP) based on hollow Prussian blue (HPB) as the functional carrier for loading α-cyano-4-hydroxycinnamate (CHC), and lactate oxidase (LOD), followed by coating with polyethylene glycol to enhance chemodynamic therapy (CDT) and the antimetastatic effect of cancer. The obtained HCLP NPs would be degraded under endogenous mild acidity within the TME to simultaneously release CHC and LOD. CHC inhibits the expression of monocarboxylate transporter 1 in tumors, thereby interrupting the uptake of lactate from the outside and alleviating tumor hypoxia by reducing lactate aerobic respiration. Meanwhile, the released LOD can catalyze the decomposition of lactate into hydrogen peroxide, further enhancing the efficacy of CDT by generating plenty of toxic reactive oxygen species through the Fenton reaction. The strong absorbance at about 800 nm endows HCLP NPs with excellent photoacoustic imaging properties. Both in vitro and in vivo studies have demonstrated that HCLP NPs can inhibit tumor growth and metastasis, providing a new possibility for tumor therapy.

Prussian Blue-Derived Nanoplatform for In Situ Amplified Photothermal/Chemodynamic/Starvation Therapy.

Chemodynamic therapy (CDT) is an emerging tumor treatment; however, it is hindered by insufficient endogenous hydrogen peroxide (H2O2) and high glutathione (GSH) concentrations in the tumor microenvironment (TME). Furthermore, CDT has limited therapeutic efficacy as a monotherapy. To overcome these limitations, in this study, a nanoplatform is designed and constructed from Cu-doped mesoporous Prussian blue (CMPB)-encapsulated glucose oxidase (GOx) with a coating of hyaluronic acid (HA) modified with a nitric oxide donor (HN). In the proposed GOx@CMPB-HN nanoparticles, the dopant Cu2+ ions are crucial to combining and mutually promoting multiple therapeutic approaches, namely, CDT, photothermal therapy (PTT), and starvation therapy. The dopant Cu2+ ions in CMPB protect against reactive oxygen species to deplete the intracellular GSH in the TME. Additionally, the byproduct Cu+ ions act as a substrate for a Fenton-like reaction that activates CDT. Moreover, H2O2, which is another important substrate, is produced in large quantities through intracellular glucose depletion caused by the nanoparticle-loaded GOx, and the gluconic acid produced in this reaction further enhances the TME acidity and creates a better catalytic environment for CDT. In addition, Cu2+ doping greatly improves the mesoporous Prussian blue (MPB) photothermal conversion performance, and the resultant increase in temperature accelerates CDT catalysis. Finally, the HN coating enables the nanoparticles to actively target CD44 receptors in cancer cells and also enhances vascular permeability. Therefore, this coating has multiple effects, such as facilitating enhanced permeability and retention and deep laser penetration. In vitro and in vivo experiments demonstrate that the proposed GOx@CMPB-HN nanoplatform significantly inhibits tumor growth with the help of in situ enhanced synergistic therapies based on the properties of the TME. The developed nanoplatform has the potential to be applied to cancer treatment and introduces new avenues for tumor treatment research.

Dual mode antibacterial surfaces based on Prussian blue and silver nanoparticles.

Prussian Blue (PB) is an inexpensive, biocompatible, photothermally active material. In this paper, self-assembled monolayers of PB nanoparticles were grafted on a glass surface, protected with a thin layer of silica and decorated with spherical silver nanoparticles. This combination of a photothermally active nanomaterial, PB, and an intrinsically antibacterial one, silver, leads to a versatile coating that can be used for medical devices and implants. The intrinsic antibacterial action of nanosilver, always active over time, can be enhanced on demand by switching on the photothermal effect of PB using near infrared (NIR) radiation, which has a good penetration depth through tissues and low side effects. Glass surfaces functionalized by this layer-by-layer approach have been characterized for their morphology and composition, and their intrinsic and photothermal antibacterial effect was studied against Gram+ and Gram- planktonic bacteria.

Prussian Blue Nanozyme Promotes the Survival Rate of Skin Flaps by Maintaining a Normal Microenvironment.

Ischemia-reperfusion (I/R) injury leads to a low success rate of skin flap transplantation in reconstruction surgery, thus requiring development of new treatments. Necroptosis and apoptosis pathways, along with overexpression of reactive oxygen species and pro-inflammatory factors in skin flap transplantation, are deemed as potential therapeutic targets. This study provides a paradigm for nanozyme-mediated microenvironment maintenance to improve the survival rate of the transplanted skin flap. Prussian blue nanozyme (PBzyme) with multiple intrinsic biological activities was constructed and selected for this proof-of-concept study. The prepared PBzyme shows anti-inflammatory, antiapoptotic, antinecroptotic, and antioxidant activities in both in vitro and in vivo models of I/R injured skin flaps. The multiple inhibitory effects of PBzyme maintained a normal microenvironment and thus significantly promoted the survival rate of the I/R injured skin flap (from 37.21 ± 8.205% to 79.61 ± 7.5%). Of note, PBzyme regulated the expression of the characteristic signal molecules of necroptosis, including Rip 1, Rip 3, and pMLKL, indicating that PBzyme may be a therapeutic agent for necroptosis-related diseases. This study shows great prospects for clinical application of PBzyme in the treatment of skin flaps via local administration.

Nanoprotection Against Retinal Pigment Epithelium Degeneration via Ferroptosis Inhibition.

Lethal oxidative stress and ferrous ion accumulation-mediated degeneration/death in retinal pigment epithelium (RPE) exert an indispensable impact on retinal degenerative diseases with irreversible visual impairment, especially in age-related macular degeneration (AMD), but corresponding pathogenesis-oriented medical intervention remains controversial. In this study, the potent iron-binding nanoscale Prussian blue analogue KCa[FeIII (CN)6 ] (CaPB) with high biocompatibility is designed to inhibit RPE death and subsequently photoreceptor cell degeneration. In mice, CaPB effectively prevents RPE degeneration and ultimately fulfills superior therapeutic outcomes upon a single intravitreal injection: significant rescue of retinal structures and visual function. Through high-throughput RNA sequencing and sophisticated biochemistry evaluations, the findings initially unveil that CaPB nanoparticles protect against RPE degradation by inhibiting ferroptotic cell fate. Together with the facile, large-scale preparations and in vivo biosafety, it is believed that the synthesized CaPB therapeutic nanoparticles are promising for future clinical treatment of diverse retinal diseases involving pathological iron-dependent ferroptosis, including AMD.

Cancer cell membrane-coated nanoparticles for bimodal imaging-guided photothermal therapy and docetaxel-enhanced immunotherapy against cancer.

BACKGROUND: Mono-therapeutic modality has limitations in combating metastatic lesions with complications. Although emerging immunotherapy exhibits preliminary success, solid tumors are usually immunosuppressive, leading to ineffective antitumor immune responses and immunotherapeutic resistance. The rational combination of several therapeutic modalities may potentially become a new therapeutic strategy to effectively combat cancer. RESULTS: Poly lactic-co-glycolic acid (PLGA, 50 mg) nanospheres were constructed with photothermal transduction agents (PTAs)-Prussian blue (PB, 2.98 mg) encapsulated in the core and chemotherapeutic docetaxel (DTX, 4.18 mg)/ immune adjuvant-imiquimod (R837, 1.57 mg) loaded in the shell. Tumor cell membranes were further coated outside PLGA nanospheres (designated "M@P-PDR"), which acted as "Nano-targeted cells" to actively accumulate in tumor sites, and were guided/monitored by photoacoustic (PA)/ magnetic resonance (MR) imaging. Upon laser irradiation, photothermal effects were triggered. Combined with DTX, PTT induced in situ tumor eradication. Assisted by the immune adjuvant R837, the maturation rate of DCs increased by 4.34-fold compared with that of the control. In addition, DTX polarized M2-phenotype tumor-associated macrophages (TAMs) to M1-phenotype, relieving the immunosuppressive TME. The proportion of M2-TAMs decreased from 68.57% to 32.80%, and the proportion of M1-TAMs increased from 37.02% to 70.81%. Integrating the above processes, the infiltration of cytotoxic T lymphocytes (CTLs) increased from 17.33% (control) to 35.5%. Primary tumors and metastasis were significantly inhibited when treated with "Nano-targeted cells"-based cocktail therapy. CONCLUSION: "Nano-targeted cells"-based therapeutic cocktail therapy is a promising approach to promote tumor regression and counter metastasis/recurrence.

Prussian blue-based theranostics for ameliorating acute kidney injury.

BACKGROUND: Acute kidney injury (AKI) with high mortality rates is associated with an excess of reactive oxygen/nitrogen species (RONS) within kidney tissues. Recently, nanomedicine antioxidant therapy has been used to alleviate AKI. Herein, we synthesized ultrasmall Prussian blue nanozymes (PB NZs, 4.5 nm) as theranostic agents for magnetic resonance (MR)/photoacoustic (PA) dual-modal imaging guided AKI treatment. RESULTS: PB NZs exhibited multi-enzyme mimetic abilities, promoting the effective elimination of RONS both in vitro and in vivo. Moreover, benefiting from their imaging contrast properties, the rapid renal accumulation of PB NZs was verified by in vivo PA/MR dual-modal imaging. Due to their excellent enrichment in the kidney and unique multi-enzyme mimetic abilities, ultrasmall PB NZs displayed superior AKI treatment efficacy compared with that of amifostine in two clinically relevant types of AKI induced murine models (either by rhabdomyolysis or cisplatin). CONCLUSION: Our findings suggested ultrasmall PB NZs, as nanozyme theranostics, have great potential for AKI management.

Self-synergistic effect of Prussian blue nanoparticles for cancer therapy: driving photothermal therapy and reducing hyperthermia-induced side effects.

BACKGROUND: Photothermal therapy (PTT), involving application of localized hyperthermia to kill cancer cells, has attracted wide attention in cancer therapy. The production of reactive oxygen species (ROS) during PTT may cause irreversible damage to healthy tissues around the tumor. Simultaneously, hyperthermia can stimulate inflammatory response, thus promoting tumor recurrence and metastasis. Therefore, it is of paramount importance to reduce the undesired side effects for further development of PTT. RESULTS: Using a hydrothermal method, spherical Prussian blue nanoparticles (PBs) with uniform size were prepared. The PBs exhibited good dispersion and stability in saline with an average hydrodynamic size of 110 nm. The prepared PBs had a high photothermal conversion efficiency and photothermal stability. The PBs showed intrinsic ROS scavenging properties in vitro. Antioxidant and anti-inflammatory effects of PBs were also observed in vivo. Assessment of toxicity and endoplasmic reticulum stress-inducing ability showed that PBs did not induce an inflammatory response. Tissues of major organs of mice stained with hematoxylin-eosin showed no significant damage, indicating good biocompatibility and safety of PBs. CONCLUSION: The designed single-component PBs with intrinsic ROS scavenging and anti-inflammatory properties could avoid inflammatory response and heat stress-induced ROS during PTT. Thus, further research on PBs is worthwhile to achieve their clinical translation and promote the development of PTT.

Finely tuned Prussian blue-based nanoparticles and their application in disease treatment.

The Prussian blue (PB) based nanostructure is a mixed-valence coordination network with excellent biosafety, remarkable photothermal effect and multiple enzyme-mimicking behaviours. Compared with other nanomaterials, PB-based nanoparticles (NPs) exhibit several unparalleled advantages in biomedical applications. This review begins with the chemical composition and physicochemical properties of PB-based NPs. The tuning strategies of PB-based NPs and their biomedical properties are systemically demonstrated. Afterwards, the biomedical applications of PB-based NPs are comprehensively recounted, mainly focusing on treatment of tumors, bacterial infection and inflammatory diseases. Finally, the challenges and future prospects of PB-based NPs and their application in disease treatment are discussed.

A novel theranostic nano-platform (PB@FePt-HA-g-PEG) for tumor chemodynamic-photothermal co-therapy and triple-modal imaging (MR/CT/PI) diagnosis.

The construction of multi-functional oncotherapy nano-platforms combining diagnosis and therapy remains a tough challenge. Prussian blue nano-cubes with optimized particle size were applied as photothermal agents and loaded with FePt NPs, effective ferroptosis agents, on the surface via an in situ reduction strategy. To attain the goal of precise medicine, hyaluronic acid was wrapped around the surface of the nanocomposites (PB@FePt NCs) for highly specific recognition of tumor cells. Finally, we successfully designed and fabricated a nano-agent (PB@FePt-HA-g-PEG NCs) to serve as a versatile nano-platform with both highly specific targeting ability for chemodynamic-photothermal co-therapy and triple-modal imaging (magnetic resonance/computed tomography/photothermal imaging) capability. Via intravenous injection, the as-constructed oncotherapy nano-platform could effectively ablate 4T1 tumor xenografts with excellent biocompatibility for chemodynamic-photothermal co-therapy. In this study we conducted a reasonable exploration to design multi-functional oncotherapy nano-platforms combining multiplexed imaging diagnosis and high therapeutic performance, which provides an innovative paradigm for precision cancer treatment.

Enhancing selective photosensitizer accumulation and oxygen supply for high-efficacy photodynamic therapy toward glioma by 5-aminolevulinic acid loaded nanoplatform.

The complex biology of glioma compromises therapeutic efficacy and results in poor prognosis. Photodynamic therapy (PDT) has emerged as a promising modality for localized tumor ablation with limited damage to healthy brain tissues. However, low photosensitizer concentration and hypoxic microenvironment in glioma tissue hamper the practical applications of PDT. To address the challenges, biocompatible periodic mesoporous organosilica coated Prussian blue nanoparticles (PB@PMOs) are constructed to load a biosafe prodrug 5-aminolevulinic acid (5-ALA), which is pronouncedly converted to protoporphyrin IX (PpIX) in malignant cells. PB@PMO-5-ALA induces a higher accumulation of PpIX in glioma cells compared to free 5-ALA. Meanwhile, the PB@PMOs, with a mean edge length of 81 nm and good biocompatibility, effectively decompose hydrogen peroxide to oxygen in a temperature-responsive manner. Oxygen supply further contributes to the promotion of 5-ALA-PDT. Thus, the photodynamic effect of PB@PMO-5-ALA is significantly improved, imposing augmented cytotoxicity to glioma U87MG cells. Furthermore, ex vivo fluorescence imaging elucidates the tumor PpIX increases by 75% in PB@PMO-5-ALA treated mice than that in 5-ALA treated ones post 12 h injection. Magnetic resonance imaging (MRI) and iron staining strongly demonstrate the accumulation of PB@PMO-5-ALA in glioma tissues with negative contrast enhancement and blue staining deposits, respectively. The nanoparticle accumulation and high PpIX level collaboratively enhance PDT efficacy through PB@PMO-5-ALA, which efficiently suppresses tumor growth, providing a promising option with safety for local glioma ablation.

Monodispersed plasmonic Prussian blue nanoparticles for zero-background SERS/MRI-guided phototherapy.

Surface-enhanced Raman scattering (SERS) and magnetic resonance imaging (MRI)-guided phototherapy are new breakthroughs in cancer therapeutics due to their complementary advantages, such as enhanced imaging spatial resolution and depth. Herein, we synthesized monodispersed Prussian blue-encapsulated gold nanoparticles (Au@PB NPs), in which the plasmonic gold core plus coordination polymer of cyanide (C[triple bond, length as m-dash]N) and iron ions coincidently become a superexcellent contrast agent for both MRI and zero-background SERS imaging. PB, as a signal source for MR and SERS, can be easily assembled onto single Au NPs, of which iron ions possess high relaxation efficiency for in vivo MRI, e.g., the longitudinal and transversal relaxation efficiency values are 0.86 mM-1 s-1 (r1) and 5.42 mM-1 s-1 (r2), respectively. Furthermore, with the help of the plasmonic enhancement of the gold core, the C[triple bond, length as m-dash]N groups exhibit a specific, strong, and stable (3S) SERS emission in the Raman-silent region (1800-2800 cm-1), allowing accurate in vivo imaging at the single or even subcellular level. More importantly, PB has remarkable absorption properties in the near infrared region, and can be used as a photosensitizer for photothermal (PT) and photodynamic (PD) therapy simultaneously. Hence, the ideal integration of a plasmonic Au core and PB shell into a single monodispersed MR-guided NP, with zero-background SERS signals, is an important candidate for both tumor navigation and in situ PT/PD treatment guided by SERS/MR dual-mode imaging.

In Situ Monitoring of the "Point Discharge" Induced Antibacterial Process by the Onsite Formation of a Raman Probe.

Electroporation induced by the "point discharge" effect is an effective technique for bacteria inactivation. Rapidly monitoring the electroporation-induced inactivation process is important for screening nanomaterials with high antimicrobial performance. In this study, we develop a facile strategy to in situ monitor the electroporation induced antimicrobial mechanism based on the surface-enhanced Raman scattering (SERS) effect of the Au-nanotip arrays. Owning to the high local-electric field (∼107 V m-1) generated on the Au nanotips, the bacteria are rapidly electroporated and effectively inactivated with ≥99.9% reduction in bacteria colony counts by only applying an external voltage of +0.8 V for 10 s. The related inactivation mechanism is directly verified by the formation of the Prussian blue (PB) nanocrystals by leaking of the uptaken [Fe(CN)6]3- ions from the cleavage area on the cell membrane. These [Fe(CN)6]3- ions react with Fe2+ to form PB nanocrystals onsite as soon as they leak out. The characteristic peak of PB in the cellular Raman-silent region provides a collective monitoring approach for the destruction of microorganisms. The present strategy not only develops a facial method for future use in evaluating electroporation materials, but also paves a rapid way for offering accurate information on some antibacterial and antitumor processes.