Catalytic Nanoparticles in Biomedical Applications: Exploiting Advanced Nanozymes for Therapeutics and Diagnostics

Catalytic nanoparticles (CNPs) as heterogeneous catalyst reveals superior activity due to their physio-chemical features, such as high surface-to-volume ratio and unique optical, electric, and magnetic properties. The CNPs, based on their physio-chemical nature, can either increase the reactive oxygen species (ROS) level for tumor and antibacterial therapy or eliminate the ROS for cytoprotection, anti-inflammation, and anti-aging. In addition, the catalytic activity of nanozymes could specifically trigger a specific reaction accompanied by the optical feature change, presenting the feasibility of biosensor and bioimaging applications. Undoubtedly, CNPs play a pivotal role in pushing the evolution of technologies in medical and clinical fields, and advanced strategies and nanomaterials rely on the input of chemical experts to develop. Herein, we present a systematic and comprehensive review of the challenges and recent development of catalytic NPs for biomedical applications from the viewpoint of advanced nanomaterial with unique catalytic activity and additional functions. Furthermore, we critically discuss the biosafety issue of applying biodegradable and non-biodegradable nanozymes and future perspectives to guide a promising direction in developing span-new nanozymes and more intelligent strategies for overcoming the current clinical limitations. This article is protected by copyright. All rights reserved.

Electroactive membrane fusion-liposome for increased electron transfer to enhance radiodynamic therapy

Dynamic therapies have potential in cancer treatments but have limitations in efficiency and penetration depth. Here a membrane-integrated liposome (MIL) is created to coat titanium dioxide (TiO2) nanoparticles to enhance electron transfer and increase radical production under low-dose X-ray irradiation. The exoelectrogenic Shewanella oneidensis MR-1 microorganism presents an innate capability for extracellular electron transfer (EET). An EET-mimicking photocatalytic system is created by coating the TiO2 nanoparticles with the MIL, which significantly enhances superoxide anions generation under low-dose (1 Gy) X-ray activation. The c-type cytochromes-constructed electron channel in the membrane mimics electron transfer to surrounding oxygen. Moreover, the hole transport in the valence band is also observed for water oxidation to produce hydroxyl radicals. The TiO2@MIL system is demonstrated against orthotopic liver tumours in vivo.

Prussian blue analog with separated active sites to catalyze water driven enhanced catalytic treatments

Chemodynamic therapy (CDT) uses the Fenton or Fenton-like reaction to yield toxic ‧OH following H2O2 → ‧OH for tumoral therapy. Unfortunately, H2O2 is often taken from the limited endogenous supply of H2O2 in cancer cells. A water oxidation CoFe Prussian blue (CFPB) nanoframes is presented to provide sustained, external energy-free self-supply of ‧OH from H2O to process CDT and/or photothermal therapy (PTT). Unexpectedly, the as-prepared CFPB nanocubes with no near-infrared (NIR) absorption is transformed into CFPB nanoframes with NIR absorption due to the increased Fe3+-N ≡ C-Fe2+ composition through the proposed proton-induced metal replacement reactions. Surprisingly, both the CFPB nanocubes and nanoframes provide for the self-supply of O2, H2O2, and ‧OH from H2O, with the nanoframe outperforming in the production of ‧OH. Simulation analysis indicates separated active sites in catalyzation of water oxidation, oxygen reduction, and Fenton-like reactions from CFPB. The liposome-covered CFPB nanoframes prepared for controllable water-driven CDT for male tumoral mice treatments.

Atomically dispersed golds on degradable zero-valent copper nanocubes augment oxygen driven Fenton-like reaction for effective orthotopic tumor therapy

Herein, we employ a galvanic replacement approach to create atomically dispersed Au on degradable zero-valent Cu nanocubes for tumor treatments on female mice. Controlling the addition of precursor HAuCl₄ allows for the fabrication of different atomic ratios of Au_xCu_y. X-ray absorption near edge spectra indicates that Au and Cu are the predominant oxidation states of zero valence. This suggests that the charges of Au and Cu remain unchanged after galvanic replacement. Specifically, Au_0.02Cu_0.98 composition reveals the enhanced •OH generation following O₂ → H₂O₂ → •OH. The degradable Au_0.02Cu_0.98 released Cu⁺ and Cu²⁺ resulting in oxygen reduction and Fenton-like reactions. Simulation studies indicate that Au single atoms boot zero-valent copper to reveal the catalytic capability of Au_0.02Cu_0.98 for O₂ → H₂O₂ → •OH as well. Instead of using endogenous H₂O₂, H₂O₂ can be sourced from the O₂ in the air through the use of nanocubes. Notably, the Au_0.02Cu_0.98 structure is degradable and renal-clearable.

Engineering H2 O2 and O2 Self-Supplying Nanoreactor to Conduct Synergistic Chemiexcited Photodynamic and Calcium-Overloaded Therapy in Orthotopic Hepatic Tumors

Photodynamic therapy (PDT) is traditionally ineffective for deeply embedded tumors due to the poor penetration depth of the excitation light. Chemiluminescence resonance energy transfer (CRET) has emerged as a promising mode of PDT without external light. To date, related research has frequently used endogenous hydrogen peroxide (H₂ O₂ ) and oxygen (O₂ ) inside the solid tumor microenvironment to trigger CRET-mediated PDT. Unfortunately, this significantly restricts treatment efficacy and the development of further biomedical applications because of the limited amounts of endogenous H₂ O₂ and O₂ . Herein, a nanohybrid (mSiO₂ /CaO₂ /CPPO/Ce6: mSCCC) nanoparticle (NP) is designed to achieve synergistic CRET-mediated PDT and calcium (Ca²⁺ )-overload-mediated therapy. The calcium peroxide (CaO₂ ) formed inside mesoporous SiO₂ (mSC) with the inclusion of the chemiluminescent agent (CPPO) and photosensitizer (Ce6) self-supplies H₂ O₂ , O₂ , and Ca²⁺ allowing for the subsequent treatments. The Ce6 in mSCCC NPs is excited by chemical energy in situ following the supply of H₂ O₂ and O₂ to produce singlet oxygen (¹ O₂ ). The nanohybrid NPs are coated with stearic acid to avoid decomposition during blood circulation through contact with aqueous environment. This nanohybrid shows promising performance in the generation of ¹ O₂ for external light-free PDT and the release of Ca²⁺ ions for Ca²⁺ -overloaded therapy against orthotopic hepatocellular carcinoma.

Polyaniline-Based Glyco-Condensation on Au Nanoparticles Enhances Immunotherapy in Lung Cancer

Lung cancer is considered among the deadliest cancers with a poor prognosis. Au@PG nanoparticles (NPs) are gold (Au)-based NPs featuring a polyaniline-based glyco structure (PG) generated from the polymerization of ortho-nitrophenyl-β-d-galactopyranoside (ONPG) with promising M1 macrophage polarization activity, resulting in tumor remodeling and from a cold to a hot microenvironment, which promotes the cytotoxic T cell response and tumor inhibition. The combination of Au@PG NPs and anti-programmed cell death protein 1 (PD-1) therapy improved tumor inhibition and immunosuppression, accompanied by the secretion of immunogenic cytokines. A one-pot synthetic method was developed to achieve glyco-condensation during the formation of Au@PG NPs, which induced macrophage polarization more efficiently than Au@glucose, Au@mannose, and Au@galactose NPs. The switch from M2 to M1 macrophages was dependent on NP size, with smaller Au@PG NPs performing better than larger ones, with effectiveness ranked as follows: 32.2 nm ≈ 29.8 nm < 26.4 nm < 18.3 nm. Cellular uptake by endocytosis induced size-dependent endoplasmic reticulum (ER) stress, which resulted in the activation of spleen tyrosine kinase (SYK), leading to immune modulations and macrophage polarization. Our results suggested the promising potential of Au@PG NPs in lung cancer immunotherapy.

Chemical Structure and Shape Enhance MR Imaging-Guided X-ray Therapy Following Marginative Delivery

Ineffective site-specific delivery has seriously impeded the efficacy of nanoparticle-based drugs to a disease site. Here, we report the preparation of three different shapes (sphere, scroll, and oblate) to systematically evaluate the impact of the marginative delivery on the efficacy of magnetic resonance (MR) imaging-guided X-ray irradiation at a low dose of 1 Gy. In addition to the shape effect, the therapeutic efficacy is investigated for the first time to be strongly related to the structure effect that is associated with the chemical activity. The enhanced particle-vessel wall interaction of both the flat scroll and oblate following margination dynamics leads to greater accumulation in the lungs, resulting in superior performance over the sphere against lung tumor growth and suppression of lung metastasis. Furthermore, the impact of the structural discrepancy in nanoparticles on therapeutic efficacy is considered. The tetragonal oblate reveals that the feasibility of the charge-transfer process outperforms the orthorhombic scroll and cubic sphere to suppress tumors. Finally, surface area is also a crucial factor affecting the efficacy of X-ray treatments from the as-prepared particles.

Synchronization of Nanoparticle Sensitization and Radiosensitizing Chemotherapy through Cell Cycle Arrest Achieving Ultralow X-ray Dose Delivery to Pancreatic Tumors

Pancreatic cancer is among the leading causes of cancer-related death and remains a formidable therapeutic challenge. To date, surgical resection and chemotherapy have been the standards of care. Methotrexate (MTX), which is recognized as a refractory drug for pancreatic cells, was conjugated to the surface of LiYF₄:Ce³⁺ nanoparticles (NP-MTX) through a photocleavable linker molecule. When LiYF₄:Ce³⁺ NPs are stimulated by X-rays, they emit light, which induces the photocleavage of the photolabile linker molecule to release MTX. MTX can target pancreatic tumors, which overexpress folic acid (FA) receptors and are internalized into the cell through receptor-mediated endocytosis. The synergistic effect of the NP-MTX treatment initiated by X-ray irradiation occurs due to the combination of nanoparticle sensitization and the radiosensitizing chemotherapy of the photocleaved MTX molecule. This dual sensitization effect mediated by NP-MTX enabled 40% dose enhancement, which corresponded with an increase in the generation of cytotoxic cellular reactive oxygen species (ROS) and enhanced S phase arrest within the cell cycle. The delivery of an ultralow radiation dose of 0.1 Gy resulted in the photocleavage of MTX from NP-MTX, and this strategy demonstrated in vivo efficacy against AsPC-1 and PANC-1 xenografted pancreatic tumors.

Phage Digestion of a Bacterial Capsule Imparts Resistance to Two Antibiotic Agents

Bacteriophages are viruses that infect bacteria, replicating and multiplying using host resources. For specific infections, bacteriophages have developed extraordinary proteins for recognizing and degrading their host. Inspired by the remarkable development of viral proteins, we used the tail fiber protein to treat multiple drug-resistant Acinetobacter baumannii. The tail fiber protein exhibits polysaccharide depolymerases activity which specifically degrades exopolysaccharide (EPS) during the phage–host interaction. However, EPS-degraded cells are observed altering host susceptibility to bacterial lysis peptide, the endolysin-derived peptide. Notably, endolysin is necessary in the process of progeny liberation by breaking the bacterial cell wall. Surprisingly, peeling the EPS animated host to resist colistin, the last-resort antibiotic used in multidrug-resistant Gram-negative bacteria infection. Tail fiber-modified cell wall reduces colistin attachment, causing temporary antibiotic-resistance and possibly raising clinical risks in treating multiple drug-resistant A. baumannii.

1550 nm excitation-responsive upconversion nanoparticles to establish dual-photodynamic therapy against pancreatic tumors

The second near-infrared biological window b (NIR-IIb, 1500-1700 nm) is recently considered as the promising region for deeper tissue penetration. Herein, a nanocarrier for 1550 nm light-responsive dual-photodynamic therapy (PDT) is developed to efficiently boost singlet oxygen (1O2) generation. The dual-photosensitizers (PSs), rose bengal (RB) and chlorin e6 (Ce6), are carried by the silica-coated core-shell LiYbF4:Er@LiGdF4 upconversion nanoparticles (UCNPs), forming UCNP/RB,Ce6. Following 1550 nm laser irradiation, the upconversion emission of UCNP/RB,Ce6 in both green (∼550 nm) and red (∼670 nm) colors is fully utilized to activate RB and Ce6, respectively. The simultaneous triggering of dual-PS generates an abundant amount of 1O2 resulting in boosted PDT efficacy. This dual-PDT nanocarrier presents an enhanced anticancer effect under single dose treatment in comparison with the single-PS ones from in vitro and in vivo treatments. The marriage between the boosted dual-PDT and 1550 nm light excitation is anticipated to provide a new avenue for non-invasive therapy.

Upconversion Nanodevice-Assisted Healthy Molecular Photocorrection

Mushrooms are rich in ergosterol, a precursor of ergocalciferol, which is a type of vitamin D₂. The conversion of ergosterol to ergocalciferol takes place in the presence of UV radiation by the cleavage of the "B-ring" in the ergosterol. As the UV radiation cannot penetrate deep into the tissue, only minimal increase occurs in sunlight. In this study, upconversion nanoparticles with the property to convert deep-penetrating near-infrared radiation to UV radiation have been cast into a disk to use sunlight and emit UV radiation for vitamin D conversion. An engineered upconversion nanoparticle (UCNP) disk with maximum particles and limited clusters demonstrates ∼2.5 times enhanced vitamin D₂ conversion.

Light triggering goldsomes enable local NO-generation and alleviate pathological vasoconstriction

While nitric oxide (NO) can remedy vasoconstriction, inhalation of NO may cause systematic toxicity. We report a goldsome, which comprises a hollowed poly(lactic-co-glycolic acid) (PLGA) polymersome with S-nitrosoglutathione (GSNO, a NO donor) molecules and gold nanoparticles (Au NPs) incorporated in its hydrophilic core and hydrophobic membrane, respectively. Photothermal heating caused breakdown of polymersomes and enabled NO generation through reaction between GSNO and Au NPs. Photo-illumination at the zebrafish head led to local NO generation and selective cerebral vasodilation while it had little effects in regions away from the illumination site, and effectively mitigated hypoxia induced cerebral vasoconstriction. We demonstrate a translational potential by showing photo-stimulated NO generation with a clinical intravascular optical catheter. In conclusion, the goldsome, which enables light stimulated local NO generation and can be delivered with clinical intravascular optical catheters, should extend applications of NO therapies while surmounting limitations associated with systemic administration.

Aspect Ratio-Dependent Charge Carrier Dynamics in Matchstick-like Ag2S-ZnS Nanorods for Solar Hydrogen Generation

Matchstick-like Ag₂S-ZnS nanorods (NRs) with a tunable aspect ratio (AR) were synthesized using one-pot thermal decomposition. The ultraviolet photoelectron spectra and time-resolved photoluminescence spectra of the Ag₂S-ZnS NRs were collected to study their electronic band structures and charge carrier dynamics. The energy difference (ΔE) at the interface between the ZnS stem and Ag₂S tip was altered as the AR of Ag₂S-ZnS NRs increased from 11.9 to 18.4, resulting in an enlarged driving force for the delocalized electrons along the conduction band of ZnS being injected into that of Ag₂S. The interfacial electron transfer rate constant (k_et) from ZnS to Ag₂S could be enhanced by ∼2 orders of magnitude from 5.27 × 10⁶ to 3.24 × 10⁸ s^-1, leading to a significant improvement in the efficiency of solar hydrogen generation. This investigation provides new physical insights into the manipulation of charge carrier dynamics by means of AR adjustment in semiconductor nanoheterostructures for photoelectric conversions.

Low Dose of X-Ray-Excited Long-Lasting Luminescent Concave Nanocubes in Highly Passive Targeting Deep-Seated Hepatic Tumors

Chromium-doped zinc gallate, ZnGa₂ O₄ :Cr³⁺ (ZGC), is viewed as a long-lasting luminescence (LLL) phosphor that can avoid tissue autofluorescence interference for in vivo imaging detection. ZGC is a cubic spinel structure, a typical agglomerative or clustered morphology lacking a defined cubic shape, but a sphere-like feature is commonly obtained for the nanometric ZGC. The substantial challenge remains achieving a well-defined cubic feature in nanoscale. The process by which dispersed and well-defined concave cubic ZGC is obtained is described, exhibiting much stronger LLL in UV and X-ray excitation for the dispersed cubic ZGC compared with the agglomerative form that cannot be excited using X-rays with a low dose of 0.5 Gy. The cubic ZGC reveals a specific accumulation in liver and 0.5 Gy used at the end of X-ray excitation is sufficient for imaging of deep-seated hepatic tumors. The ZGC nanocubes show highly passive targeting of orthotopic hepatic tumors.

Enhancing Microcirculation on Multitriggering Manner Facilitates Angiogenesis and Collagen Deposition on Wound Healing by Photoreleased NO from Hemin-Derivatized Colloids

A deficiency of nitric oxide (NO) supply has been found to impair wound healing. The exogenous topical delivery of NO is a promising approach to enhance vasodilation and stimulate angiogenesis and collagen deposition. In this study, the CN groups on the surface of Prussian blue (PB) nanocubes were carefully reduced to -CH₂-NH₂ to conjugate with COOH group of hemin consisting of a Fe-porphyrin structure with strong affinity toward NO. Accordingly, the NO gas was able to coordinate to hemin-modified PB nanocubes. The hemin-modified PB carrying NO (PB-NO) can be responsible to near-infrared (NIR) light (808 nm) exposure to induce the thermo-induced liberation of NO based on the light-to-heat transformation property of PB nanocubes. The NO supply on the incisional wound sites can be readily topically dropped the colloidal solution of PB-NO for receiving NIR light irradiation. The enhanced blood flow was in a controllable manner whenever the wound sites containing PB-NO received NIR light irradiation. The promotion of blood perfusion following the on-demand multidelivery of NO has effectively facilitated the process of wound closure to enhance angiogensis and collagen deposition.

Abstract WMP27: Selective Cerebral Vasodilatation and Anti-Apoptotic Therapy With Shockwave-Induced Release of Nitric Oxide Using Nano Au-polymersomes/S-nitrosoglutathione

Introduction: Cerebral vasoconstriction is often encountered in the post-CPR phase, which inevitably worsens neurological prognosis. Nitric oxide (NO) confers vasodilatation and anti-apoptotic protective effect, but may cause systemic hypotension. We designed an Au-polymersomes/S-nitrosoglutathione (Au-PLGA/GSNO) nanoparticle that can be selectively triggered by shockwave (SW) to release NO, and investigated its role in mitigating post-CPR cerebral vasoconstriction and apoptotic neuronal injury.

Methods: Using an established rat model of asphyxia cardiac arrest and CPR, Au-PLGA/GSNO (7500 PPM, 3.33 mg/kg Au and 42 ug/kg GSNO) was infused into carotid artery together with the same volume of SonoVue 10 min after CPR, with simultaneous stimulation by SW (PiezoWave, 134 mJ/mm 2 ) distal to the infusion site. The blood pressure (BP) was continuously monitored and brain tissue perfusion recorded by OxyFLO probe. Cerebral vasculature was video-taped by CytoCam. The blood was sampled 2 h post-CPR for measurement of nitrate/nitrite. The brain was harvested for measurement of casepase-3, endothelial NO synthase (eNOS) and protein kinase B (Akt). In a subgroup the brain was harvested at 24 h for TUNEL stain.

Results: Marked cerebral vasoconstriction was noted after CPR with brain perfusion reduced to about half that of baseline. With infusion of Au-PLGA/GSNO + SonoVue and SW stimulation, the cerebral vasoconstriction was ameliorated and brain perfusion improved to baseline level ( P < 0.05 vs. CPR control), while BP showed no significant difference. The plasma nitrate/nitrite 2 h post-CPR was significantly increased ( P < 0.05). The cleaved caspase-3 of the brain was reduced ( P < 0.001) and TUNEL stain of the CA1 and CA3 regions of hippocampus significantly abrogated. Interestingly, the phosphorylated (P)-eNOS and P-Akt were also increased (both P < 0.001), suggesting reciprocating activation of the upstream Akt-eNOS signaling.

Conclusion: Nano Au-PLGA/GSNO with SW-induced release of NO selectively mitigates post-CPR cerebral vasoconstriction and apoptotic neuronal death without systemic hypotension. Being effective and safe, such therapeutic strategy can be applied not only in post-CPR care but in other diseases such as subarachnoid hemorrhage.

Tuning the Distance of Rattle-Shaped IONP@Shell-in-Shell Nanoparticles for Magnetically-Targeted Photothermal Therapy in the Second Near-Infrared Window

Construction of multifunctional nanoparticles (NPs) with near-infrared (NIR) plasmonic responses is considered a versatile and multifaceted platform for several biomedical applications. Herein, a double layer of Au/Ag alloy on the surface of truncated octahedral iron oxide NPs (IONPs) was prepared and the distance between the layers was controlled to exhibit broad and strong NIR absorption. The rattle-shaped IONP@shell-in-shell nanostructure showed light-response to the NIR biological window from 650 to 1300 nm for photothermal therapy (PTT) and magnetic guidance for hyperthermia and magnetic resonance imaging (MRI) diagnosis. Exposing the aqueous solution of IONP@shell-in-shell to a 1064 nm diode laser, its heat conversion efficiency was ∼28.3%. The in vitro cell viability at a gold concentration of 100 ppm was ∼85%, and decreased to ∼16% when the cells were treated with the NIR irradiation and magnetic attraction. T₂-weighted MRI images showed a clear accumulation of IONP@shell-in-shell at the tumor site with magnetic attraction. In vivo luminescence tumor images explained that the IONP@shell-in-shell could reduce the U87MG-luc2 cancer cell proliferation in mice with the NIR irradiation and magnetic attraction. These results indicate the IONP@shell-in-shell as a promising nanomedicine for PTT, magnetic targeting, and magnetic resonance imaging (MRI).

Octahedron Iron Oxide Nanocrystals Prohibited Clostridium difficile Spore Germination and Attenuated Local and Systemic Inflammation

Clinical management of Clostridium difficile infection is still far from satisfactory as bacterial spores are resistant to many chemical agents and physical treatments. Certain types of nanoparticles have been demonstrated to exhibit anti-microbial efficacy even in multi-drug resistance bacteria. However, most of these studies failed to show biocompatibility to the mammalian host cells and no study has revealed in vivo efficacy in C. difficile infection animal models. The spores treated with 500 µg/mL Fe_3-δO₄ nanoparticles for 20 minutes, 64% of the spores were inhibited from transforming into vegetative cells, which was close to the results of the sodium hypochlorite-treated positive control. By cryo-electron micro-tomography, we demonstrated that Fe_3-δO₄ nanoparticles bind on spore surfaces and reduce the dipicolinic acid (DPA) released by the spores. In a C. difficile infection animal model, the inflammatory level triple decreased in mice with colonic C. difficile spores treated with Fe_3-δO₄ nanoparticles. Histopathological analysis showed a decreased intense neutrophil accumulation in the colon tissue of the Fe_3-δO₄ nanoparticle-treated mice. Fe_3-δO₄ nanoparticles, which had no influence on gut microbiota and apparent side effects in vivo, were efficacious inhibitors of C. difficile spore germination by attacking its surface and might become clinically feasible for prophylaxis and therapy.

CO2 Delivery To Accelerate Incisional Wound Healing Following Single Irradiation of Near-Infrared Lamp on the Coordinated Colloids

Traditional wound care methods include wound infection control, adequate nutritional supplements, education of changing position every 2-3 h to avoid tissue hypoxia, vacuum assistant closure, debridement, skin graft, and tissue flap. Electric current stimulation, ultrasound, laser, and hydrotherapy have emerged as adjuvant therapies. However, most, if not all, of these therapies are expensive, and the treatment results are variable. The development of the active methods to improve wound healing is mandatory. CO₂ administration has been known to improve microcirculation and local oxygen supply that are beneficial to wound healing. Here, the metal ion-ligand coordination nanoarchitecture was designed to reveal NIR light-induced CO₂ generation for wound healing. The administration simply topically dropped the colloidal solution on the incisional wound, followed by exposure of near-infrared (NIR) lamp to yield CO₂, resulting in the observation of the accelerated wound healing.

Hollow mesoporous silica nanosphere-supported FePt nanoparticles for potential theranostic applications

A nanocomposite comprising FePt nanoparticles and hollow mesoporous silica nanospheres has been fabricated for MRI, NIR photothermal therapy and combined chemo-/thermotherapy.

Controllable CO Release Following Near-Infrared Light-Induced Cleavage of Iron Carbonyl Derivatized Prussian Blue Nanoparticles for CO-Assisted Synergistic Treatment

Carbon monoxide (CO) causes the dysfunction of mitochondria to induce the apoptosis of cancer cells giving a promising choice as an emerging treatment. The currently reported CO-based complexes still suffer from many limitations. Synthesis of CO-release carriers in the manner of on-demand control is highly anticipated. In this study, we present a near-infrared (NIR) light-responsive CO-delivery nanocarrier, a PEGylated iron carbonyl derivatized Prussian blue (PB) nanoparticle (NP). Taking the structural characteristic containing Fe³⁺-N≡C-Fe²⁺ unit, the -CN^- served as the active sites for the coordination of iron carbonyl, while the surface Fe sites chelated with the amine-functionalized polyethylene glycol (NH₂-PEG₆₀₀₀-NH₂) to yield PEGylated PB NPs carrying CO. The control of light intensity and exposure period is important to release the amount of CO as well as to deliver the hyperthermia effect. The combination therapy including CO and photothermal treatments displayed a synergistic effect against cancer cells. Importantly, the release of CO is inert in the blood circulation without NIR irradiation. The blood oxygen saturation measured by the pulse oximeter and the HCO₃, tCO₂, and pH values analyzed by the blood assay revealed the steady status from the mice studies, showing no acute CO poisoning.

Controllable NO release from Cu1.6S nanoparticle decomposition of S-nitrosoglutathiones following photothermal disintegration of polymersomes to elicit cerebral vasodilatory activity

Since the discovery of nitric oxide (NO) as a vasodilator, numerous NO therapies have been attempted to remedy disorders related to pathological vasoconstriction such as coronary artery disease. Despite the advances, clinical applications of NO therapies remain limited mainly because of the low stability of molecular NO donors (and NO molecules), and concerns about the increased oxidative stress and reduced arterial pressure associated with the systemic administration of NO. Here we design a photo-responsive polymersome with nitrosothiols and Cu_1.6S nanoparticles in its core and shell, respectively, and demonstrate the photo-triggered release of NO and its vasodilatory activity on zebrafish. Unlike conventional approaches, our design enhances the stability of NO donors and prospectively enables spatiotemporal regulation of NO release, thus minimizing the harmful effects associated with conventional NO therapies. We anticipate that such a strategy will open up new clinical applications of NO and help reveal the complex biological effects of NO in vivo.

Fabrication of Silica-Coated Hollow Carbon Nanospheres Encapsulating Fe3O4 Cluster for Magnetical and MR Imaging Guided NIR Light Triggering Hyperthermia and Ultrasound Imaging

Iron oxide nanoparticles (IONPs)-carbon (C) hybrid zero-dimensional nanostructures normally can be categorized into core-shell and yolk-shell architectures. Although IONP-C is a promising theranostic nanoagent, the in vivo study has surprisingly been less described. In addition, little effort has strived toward the fabrication of yolk-shell compared to the core-shell structures. In this context, we synthesized a yolk-shell type of the silica-coated hollow carbon nanospheres encapsulating IONPs cluster, which can be dispersed in aqueous solution for systemic studies in vivo, via the preparation involving the mixed micellization, polymerization/hollowing, sol-gel (hydration-condensation), and pyrolysis processes. Through a surface modification of the polyethylenimine followed by the sol-gel process, the silica shell coating was able to escape from condensing and sintering courses resulting in aggregation, due to the annealing. Not limited to the well-known functionalities in magnetical targeting and magnetic resonance (MR) imaging for IONP-C hybrid structures, we expanded this yolk-shell NPs as a near-infrared (NIR) light-responsive echogenic nanoagent giving an enhanced ultrasound imaging. Overall, we fabricated the NIR sensitive yolk-shell IONP-C to activate ultrasound imaging and photothermal ablation under magnetically and MR imaging guided therapy.

Bacteria-Mediated Hypoxia-Specific Delivery of Nanoparticles for Tumors Imaging and Therapy

The hypoxia region in a solid tumor has been recognized as a complex microenvironment revealing very low oxygen concentration and deficient nutrients. The hypoxic environment reduces the susceptibility of the cancer cells to anticancer drugs, low response of free radicals, and less proliferation of cancer cells in the center of the solid tumors. However, the reduced oxygen surroundings provide an appreciable habitat for anaerobic bacteria to colonize. Here, we present the bacteria-mediated targeting hypoxia to offer the expandable spectra for diagnosis and therapy in cancer diseases. Two delivery approaches involving a cargo-carrying method and an antibody-directed method were designed to deliver upconversion nanorods for imaging and Au nanorods for photothermal ablation upon near-infrared light excitation for two forms of the anaerobic Bifidobacterium breve and Clostridium difficile. The antibody-directed strategy shows the most effective treatment giving stronger imaging and longer retention period and effective therapy to completely remove tumors.

Ultrasound-Induced Reactive Oxygen Species Mediated Therapy and Imaging Using a Fenton Reaction Activable Polymersome

Ultrasound techniques have been extensively employed for diagnostic purposes. Because of its features of low cost, easy access, and noninvasive real-time imaging, toward clinical practice it is highly anticipated to simply use diagnostic ultrasound to concurrently perform imaging and therapy. We report a H2O2-filled polymersome to display echogenic reflectivity and reactive oxygen species-mediated cancer therapy simply triggered by the microultrasound diagnostic system accompanied by MR imaging. Instead of filling common perfluorocarbons, the encapsulation of H2O2 in H2O2/Fe3O4-PLGA polymersome provides O2 as the echogenic source and (•)OH as the therapeutic element. On exposure to ultrasound, the polymersome can be easily disrupted to yield (•)OH through the Fenton reaction by reaction of H2O2 and Fe3O4. We showed that malignant tumors can be completely removed in a nonthermal process.

Syntheses of Platinum-Sulindac Complexes and Their Nanoparticles as Targeted Anticancer Drugs

Platinum(II)-sulindac complexes [{η² -C₅ H₄ SN(O)}Pt(DMSO){O(C=O)Sulindac}], [{η² -C₅ H₄ SN(O)}PtCl{(S=O)Sulindac}], [{η² -C₅ H₄ SN(O)}PtCl{(S=O)Sulindac-succinimide}], and [{η² -C₅ H₄ SN(O)}PtCl{(S=O)Sulindac-thymidine}] were synthesized that exhibited IC₅₀ values of 2.9-4.8 μm against human oral cancer cells OECM1. The poly(lactic-co-glycolic acid) (PLGA) encapsulated [{η² -C₅ H₄ SN(O)}PtCl{(S=O)Sulindac}] also showed cytotoxic activity although less potent than the pristine species.

Gold over Branched Palladium Nanostructures for Photothermal Cancer Therapy

Bimetallic nanostructures show exciting potential as materials for effective photothermal hyperthermia therapy. We report the seed-mediated synthesis of palladium-gold (Pd-Au) nanostructures containing multiple gold nanocrystals on highly branched palladium seeds. The nanostructures were synthesized via the addition of a gold precursor to a palladium seed solution in the presence of oleylamine, which acts as both a reducing and a stabilizing agent. The interaction and the electronic coupling between gold nanocrystals and between palladium and gold broadened and red-shifted the localized surface plasmon resonance absorption maximum of the gold nanocrystals into the near-infrared region, to give enhanced suitability for photothermal hyperthermia therapy. Pd-Au heterostructures irradiated with an 808 nm laser light caused destruction of HeLa cancer cells in vitro, as well as complete destruction of tumor xenographs in mouse models in vivo for effective photothermal hyperthermia.

Charge collection enhancement by incorporation of gold-silica core-shell nanoparticles into P3HT:PCBM/ZnO nanorod array hybrid solar cells

In this work, gold-silica core-shell (Au@silica) nanoparticles (NPs) with various silica-shell thicknesses are incorporated into P3HT:PCBM/ZnO nanorod (NR) hybrid solar cells. Enhancement in the short-circuit current density and the efficiency of the hybrid solar cells is attained with the appropriate addition of Au@silica NPs regardless of the silica-shell thickness. Compared to the P3HT:PCBM/ZnO NR hybrid solar cell, a 63% enhancement in the efficiency is achieved by the P3HT:PCBM/Au@silica NP/ZnO NR hybrid solar cell. The finite difference time domain simulations indicate that the strength of the Fano resonance, i.e., the electric field of the quasi-static asymmetric quadrupole, on the surface of Au@silica NPs in the P3HT:PCBM/ZnO NR hybrid significantly decreases with increasing thickness of the silica shell. Raman characterization reveals that the degree of P3HT order increases when Au@silica NPs are incorporated into the P3HT:PCBM/ZnO NR hybrid. The charge separation at the interface between P3HT and PCBM as well as the electron transport in the active layer are retarded by the electric field of the Fano resonance. Nevertheless, the prolongation of the electron lifetime and the reduction of the electron transit time in the P3HT:PCBM/ZnO NR hybrid solar cells, which result in an enhancement of electron collection, are achieved by the addition of Au@silica NPs. This may be attributed to the improvement in the degree of P3HT order and connectivity of PCBM when Au@silica NPs are incorporated into the P3HT:PCBM active layer.

Antimicrobial applications of water-dispersible magnetic nanoparticles in biomedicine

The increasing morbidity and mortality of infectious diseases is an increasing concern. Despite the continuous development and synthesis of new antimicrobial drugs, microbial pathogens are exhibiting increased multi-drug resistance. Nanomaterials display unique and well-defined physical and chemical properties including a very high surface area to volume ratio, and new approaches for antimicrobial therapies have attempted to combine nanomaterials and current antimicrobial drugs. Magnetic nanoparticles (MNPs) are characterized by biocompatibility, biodegradation, and safety for human ingestion. Iron oxide nanoparticles have been approved for human use by the US Food and Drug Administration (FDA). For biomedicine applications, MNPs require surface modification to become water-soluble and be stable enough to resist the effects of proteins and salts in the physiological environment. MNPs can combine various substrata, such as biomolecules and nanomaterials to generate new antimicrobial agents which combine antibacterial, antiviral, and antifungal properties. This can be accomplished through a series of surface modification methods. Because MNPs have unique superparamagnetic characteristics, they can be controlled and recycled by an external magnetic field.In addition, the antimicrobial activity of MNPs-based nanocomposites is superior to that of metallic nanoparticles. This paper reviews the recent literature on the use of MNP-based nanomaterials in antimicrobial applications in biomedicine. Antimicrobial applications mainly focus on inhibiting and killing bacteria and fungi and viruses inactivation. The synthesis, surface modification, and characteristics related to MNPs will also be briefly addressed.

P3HT-based nanoarchitectural Fano solar cells

The finite difference time domain simulation shows the existence of an asymmetric quadrupole of Fano resonance on the surface of a gold-silica core-shell (Au@silica) nanoparticle (NP) as being incorporated into the metal oxide nanoarchitecture/P3HT hybrid. Compared to the metal oxide nanoarchitecture/P3HT hybrid solar cell, a 30% enrichment of the short-circuit current density (Jsc) is attained in the P3HT-based nanoarchitectural Fano solar cell with the Au@silica NPs. The enhancement of charge separation in the cell by the electric field of the Fano resonance is directly evidenced by time-resolved photoluminescence measurements. The increase of the degree of P3HT order in the hybrid by the incorporation of Au@silica NPs into the hybrid active layer may also contribute to the enhancement in the Jsc. Charge carrier dynamic measurements show that an electron collection efficiency of ∼97% can be maintained in the P3HT-based nanoarchitectural Fano solar cell. Significant improvement of the efficiency of the inverted metal oxide/P3HT hybrid solar cell is therefore achieved.

Formation of oligonucleotide-gated silica shell-coated Fe₃O₄-Au core-shell nanotrisoctahedra for magnetically targeted and near-infrared light-responsive theranostic platform

A new multifunctional nanoparticle to perform a near-infrared (NIR)-responsive remote control drug release behavior was designed for applications in the biomedical field. Different from the previous studies in formation of Fe3O4-Au core-shell nanoparticles resulting in a spherical morphology, the heterostructure with polyhedral core and shell was presented with the truncated octahedral Fe3O4 nanoparticle as the core over a layer of trisoctahedral Au shell. The strategy of Fe3O4@polymer@Au was adopted using poly-l-lysine as the mediate layer, followed by the subsequent seeded growth of Au nanoparticles to form a Au trisoctahedral shell. Fe3O4@Au trisoctahedra possess high-index facets of {441}. To combine photothermal and chemotherapy in a remote-control manner, the trisoctahedral core-shell Fe3O4@Au nanoparticles were further covered with a mesoporous silica shell, yielding Fe3O4@Au@mSiO2. The bondable oligonucleotides (referred as dsDNA) were used as pore blockers of the mesoporous silica shell that allowed the controlled release, resulting in a NIR-responsive DNA-gated Fe3O4@Au@mSiO2 nanocarrier. Taking advantage of the magnetism, remotely triggered drug release was facilitated by magnetic attraction accompanied by the introduction of NIR radiation. DNA-gated Fe3O4@Au@mSiO2 serves as a drug control and release carrier that features functions of magnetic target, MRI diagnosis, and combination therapy through the manipulation of a magnet and a NIR laser. The results verified the significant therapeutic effects on tumors with the assistance of combination therapy consisting of magnetic guidance and remote NIR control.

Oligonucleotides--assembled Au nanorod-assisted cancer photothermal ablation and combination chemotherapy with targeted dual-drug delivery of Doxorubicin and Cisplatin prodrug

External stimuli responsive dual drugs carrier was synthesized with Au nanorods (NRs) as the platform. On Au NRs, single stranded DNAs were assembled using 5' thiol end. Following this, complementary DNA (cDNA) strands were hybridized. This hybridized double stranded DNA facilitated doxorubicin (Dox) intercalation into the duplexes. The cDNA designed with the 5' amine functional group assisted to tether platinum [Pt(IV)] prodrugs by establishing amide bond with the acid group at the axial ligand. The other axial acid group in Pt(IV) prodrugs was conjugated with the folic acid (FA) to target folate receptors overexpressed in the cancer cells. This targeting vehicle provided remote-controlled delivery of this high toxic cargo cocktail at the tumor site, ensuring extra specificity that can avoid acute toxicity, where release of Dox and Pt(IV) was achieved upon NIR 808 nm diode laser irradiation. The dehybridization set the Dox free to bind the cell nucleus and cellular reductants reduced Pt(IV) to yield toxic Pt(II), becoming an active drug. The in vitro and in vivo studies revealed that this external stimulus responsive combination drug delivery was significantly effective.

Near-infrared light-responsive nanomaterials in cancer therapeutics

Near-infrared light sensitive nanomaterials provide ideal nanoplatforms in site specific noninvasive cancer therapy.

Near-infrared light photocontrolled targeting, bioimaging, and chemotherapy with caged upconversion nanoparticles in vitro and in vivo

The major challenge in current chemotherapy is to increase local effective therapeutic concentration of drugs as well as to minimize toxicity and side effects for patients. The targeted delivery of drugs to their desired site of action in a controlled manner plays an essential role in the development of drug formulations. A photocage refers to a caged molecule rendered biologically inert by a photolabile protecting group. Molecules are illuminated with light to liberate the caged group and then become active forms. In this study, we formulate upconversion nanoparticles (UCNPs) as the NIR-triggered targeting and drug delivery vehicles that successfully deliver in vitro and in vivo for near-infrared light photocontrolled targeting, bioimaging, and chemotherapy. It is noted that there has been no report on the systemic administration UCNP-based drug delivery agents for evaluation of bioimaging and chemotherapy. To achieve phototargeting, the tumor-homing agent (i.e., folic acid) has been constructed as a photoresponsive molecule. For the chemotherapeutic effect, the antitumor drug doxorubicin is thiolated on the surface of UCNPs, forming a disulfide bond that can be cleaved by lysosomal enzymes within the cells. The caged UNCPs can serve as a platform for the improvement of selective targeting and possible reduction of adverse side effects from chemotherapy.

Preparation of superparamagnetic Mn(x)Fe(1-x)O nanoparticles from low-index-facet cubes to high-index-facet concave structures and their catalytic performance in aqueous solution

We report the synthesis of concave magnetic Mn(x)Fe(1-x)O nanoparticles with high-index facet structures by a thermal decomposition approach. The particle morphology varies from cubic shape under pure Ar, to star-like shapes with exposure to air during the reaction. The oxidative etching in the presence of air (O2) strongly affects the exposed facets on the surface. These concave nanoparticles are transferred from the organic phase to aqueous solution and show distinct catalytic activity toward the degradation of xylenol orange in aqueous solution.

Pronounced induction of endoplasmic reticulum stress and tumor suppression by surfactant-free poly(lactic-co-glycolic acid) nanoparticles via modulation of the PI3K signaling pathway

Background

Y294002 (LY) is a potent inhibitor of phosphatidylinositol 3-kinases (PI3Ks); however, biological applications of LY are limited by its poor solubility and pharmacokinetic profile. This study aimed at developing LY-loaded surfactant-free poly(lactic-co-glycolic acid) (PLGA) nanoparticles (SF-LY NPs) to improve the therapeutic efficacy of LY.

Materials and methods

Cellular viability was measured by MTT assay. The subcellular distribution of NPs was studied using an ultraviolet-visible spectrophotometer and confocal microscope. The expression of cell-death-associated proteins was determined using Western blotting and the in vivo activity of SF-LY NPs was tested in a xenograft animal model.

Results

SF-LY NPs enhanced the intracellular level of LY, induced sustained suppression of AKT, and induced marked cancer cell death. In addition, SF-LY NPs tended to accumulate in the endoplasmic reticulum (ER) and induce pronounced ER stress. Finally, SF-LY NPs exhibited a prominent antitumor effect in vivo.

Conclusion

The surfactant-free formulation of PLGA is critical to the promising anticancer activity of SF-LY NPs.

Au nanorod design as light-absorber in the first and second biological near-infrared windows for in vivo photothermal therapy

Photothermal cancer therapy using near-infrared (NIR) laser radiation is an emerging treatment. In the NIR region, two biological transparency windows are located in 650-950 nm (first NIR window) and 1000-1350 nm (second NIR window) with optimal tissue transmission obtained from low scattering and energy absorption, thus providing maximum radiation penetration through tissue and minimizing autofluorescence. To date, intensive effort has resulted in the generation of various methods that can be used to shift the absorbance of nanomaterials to the 650-950 nm NIR regions for studying photoinduced therapy. However, NIR light absorbers smaller than 100 nm in the second NIR region have been scant. We report that a Au nanorod (NR) can be designed with a rod-in-shell (rattle-like) structure smaller than 100 nm that is tailored to be responsive to the first and second NIR windows, in which we can perform hyperthermia-based therapy. In vitro performance clearly displays high efficacy in the NIR photothermal destruction of cancer cells, showing large cell-damaged area beyond the laser-irradiated area. This marked phenomenon has made the rod-in-shell structure a promising hyperthermia agent for the in vivo photothermal ablation of solid tumors when activated using a continuous-wave 808 m (first NIR window) or a 1064 nm (second NIR window) diode laser. We tailored the UV-vis-NIR spectrum of the rod-in-shell structure by changing the gap distance between the Au NR core and the AuAg nanoshell, to evaluate the therapeutic effect of using a 1064 nm diode laser. Regarding the first NIR window with the use of an 808 nm diode laser, rod-in-shell particles exhibit a more effective anticancer efficacy in the laser ablation of solid tumors compared to Au NRs.

Escape from the destruction of the galvanic replacement reaction for solid → hollow → solid conversion process in one pot reaction

Based on the difference in the redox potentials between two metal species, the galvanic replacement reaction is known to create an irreversible process to generate hollow nanostructures in a wide range of shapes. In the context of galvanic replacement reaction, continuing etching leads to the general collapse of the hollow structures because of the excess amount of oxidizing agent. We demonstrate the growth of solid nanostructures from a hollow frame-like architecture in the course of a galvanic replacement reaction without any morphology destruction. We report the successful composition transformation of solid Ag with a wide range of shapes, such as plate, decahedron, rod, prism, sphere, and foil, from as thin as <10 nm up to 5 μm and with an area of ∼4 mm(2), to their solid Au counterparts using straightforward chemical reactions. The successful conversion process relies on a decrease in the reduction rate of the metallic precursor to initiate dissolution of Ag in the first stage (a galvanic replacement reaction), then a subsequent backfilling of Au into the hollowed-out structures. Cetyltrimethylammonium bromide (CTAB) surfactant, a key parameter, interacts with metal salt precursor to form a complex species that retards metal reduction. In addition, we demonstrate conversion of solid nano-Ag to solid nano-Pd as well as of Cu foil (10 μm thick) to shiny Au foil.

Electrostatic droplets assisted in situ synthesis of superparamagnetic chitosan microparticles for magnetic-responsive controlled drug release and copper ion removal

This paper demonstrates a facile approach for the in situ synthesis of size-controllable superparamagnetic chitosan micro-beads with a saturation magnetization value as high as ca. 35.3 emu g^-1 at room temperature. The proposed process utilized the electrostatic droplets (ESD) technique, which is quite effective in producing uniform-sized polymer beads. A sodium hydroxide solution was employed for both the solidification of chitosan and the co-precipitation of ferro-gels containing both ferrous and ferric cations. The diameter of the beads was very uniform (each relative standard deviation was below 3.4%) and adjustable from 84 μm to ca. 555 μm by varying the electrostatic field. Cell viability tests indicated that the superparamagnetic chitosan particles were eco-friendly and had a high potential for biological applications. The results show that the superparamagnetic chitosan particles achieved superior results in magnetic-responsive drug release as well as heavy metal removal (e.g. copper ions). This study demonstrated that the appropriate magnetic field intensity for different release patterns is predictable, which allows for better application of microcapsules as a smart drug carrier. In addition, the proposed chitosan particles serve as an alternative material for the adsorption of heavy metal ions from contaminated industrial effluents, while their superparamagnetic properties are advantageous in that they make the chitosan particles guidable by an external magnetic field.