Therapeutic gas-releasing nanomedicines with controlled release: Advances and perspectives

Ultrasound-driven radical chain reaction and immunoregulation of piezoelectric-based hybrid coating for treating implant infection

The poor efficiency of US-responsive coatings on implants restricts their practical application. Immunotherapy that stimulates immune cells to enhance their antibacterial activity is expected to synergize with sonodynamic therapy for treating implant infection effectively and safely. Herein, US-responsive hybrid coatings composed of the oxygen-deficient BaTiO3 nanorod arrays and l-arginine (BaTiO3-x/LA) are designed and prepared on titanium implants for sonocatalytic therapy-cooperated immunotherapy to treat Methicillin-resistant Staphylococcus aureus (MRSA) infection. BaTiO3-x/LA can generate more oxidizing reactive oxygen species (ROS, hydroxyl radical (·OH)) and reactive nitrogen species (RNS, peroxynitrite anion (ONOO-)). The construction of nanorod arrays and oxygen defects balances the piezoelectric properties and sonocatalytic capability during US treatment. The generated piezoelectric electric field provides a sufficient driving force to separate electrons and holes, and the oxygen defects attenuate the electron-hole recombination efficiency, consequently increasing the yield of ROS during the US treatment. Moreover, nitric oxide (NO) released by l-arginine reacts with the superoxide radical (·O2-) to produce ONOO-. Since, this radical chain reaction improves the oxidizing ability between bacteria and radicals, the cell membrane (argB, secA2) and DNA (dnaBGXN) are destroyed. The bacterial self-repair mechanism indirectly accelerates bacterial death based on the transcriptome analysis. In addition to participating in the radical chain reaction, NO positively affects macrophage M1 polarization to yield potent phagocytosis to MRSA. As a result, without introducing an extra sonosensitizer, BaTiO3-x/LA exhibits excellent antibacterial activity against MRSA after the US treatment for 15 min. Furthermore, BaTiO3-x/LA facilitates macrophage M2 polarization after implantation and improves osteogenic differentiation. The combined effects of sonodynamic therapy and immunoregulation lead to an effective and safe treatment method for implant-associated infections.

Cobalt-based hybrid nanoparticles loaded with curcumin for ligand-enhanced synergistic nanocatalytic therapy/chemotherapy combined with calcium overload

The therapeutic efficacy of Fenton or Fenton-like nanocatalysts is usually restricted by the inappropriate pH value and limited concentration of hydrogen peroxide (H2O2) at the tumor site. Herein, calcium carbonate (CaCO3)-mineralized cobalt silicate hydroxide hollow nanocatalysts (CSO@CaCO3, CC) were synthesized and loaded with curcumin (CCC). This hybrid system can simultaneously realize nanocatalytic therapy, chemotherapy and calcium overload. With the stabilization of liposomes, CCC is able to reach the tumor site smoothly. The CaCO3 shell first degrades in an acidic tumor environment, releasing Cur and Ca2+, and the pH value of the tumor is increased simultaneously. Then the exposed CSO catalyzes the Fenton-like reaction to convert H2O2 into ˙OH and enhances the cytotoxicity of curcumin (Cur) by catalytically oxidizing it to a ˙Cur radical. Curcumin not only induces the chemotherapy effect but also serves as a nucleophilic ligand and an electron donor in the catalytic system, enhancing the Fenton-like activity of CCC by electron transfer. In addition, calcium overload also amplifies the efficacy of ROS-based therapy. In vitro and in vivo results show that CCC exhibited an excellent synergistic tumor inhibition effect without any clear side effect. This work proposes a novel concept of nanocatalytic therapy/chemotherapy synergistic mechanism by the ligand-induced enhancement of Fenton-like catalytic activity, and inspires the construction of combined therapeutic nanoplatforms and multifunctional nanocarriers for drug and ion delivery in the future.

Photodynamic and nitric oxide therapy-based synergistic antimicrobial nanoplatform: an advanced root canal irrigation system for endodontic bacterial infections

BACKGROUND

The main issues faced during the treatment of apical periodontitis are the management of bacterial infection and the facilitation of the repair of alveolar bone defects to shorten disease duration. Conventional root canal irrigants are limited in their efficacy and are associated with several side effects. This study introduces a synergistic therapy based on nitric oxide (NO) and antimicrobial photodynamic therapy (aPDT) for the treatment of apical periodontitis.

RESULTS

This research developed a multifunctional nanoparticle, CGP, utilizing guanidinylated poly (ethylene glycol)-poly (ε-Caprolactone) polymer as a carrier, internally loaded with the photosensitizer chlorin e6. During root canal irrigation, the guanidino groups on the surface of CGP enabled effective biofilm penetration. These groups undergo oxidation by hydrogen peroxide in the aPDT process, triggering the release of NO without hindering the production of singlet oxygen. The generated NO significantly enhanced the antimicrobial capability and biofilm eradication efficacy of aPDT. Furthermore, CGP not only outperforms conventional aPDT in eradicating biofilms but also effectively promotes the repair of alveolar bone defects post-eradication. Importantly, our findings reveal that CGP exhibits significantly higher biosafety compared to sodium hypochlorite, alongside superior therapeutic efficacy in a rat model of apical periodontitis.

CONCLUSIONS

This study demonstrates that CGP, an effective root irrigation system based on aPDT and NO, has a promising application in root canal therapy.

H2S-Releasing Versatile Montmorillonite Nanoformulation Trilogically Renovates the Gut Microenvironment for Inflammatory Bowel Disease Modulation

Abnormal activation of the intestinal mucosal immune system, resulting from damage to the intestinal mucosal barrier and extensive invasion by pathogens, contributes to the pathogenesis of inflammatory bowel disease (IBD). Current first-line treatments for IBD have limited efficacy and significant side effects. An innovative H2S-releasing montmorillonite nanoformulation (DPs@MMT) capable of remodeling intestinal mucosal immune homeostasis, repairing the mucosal barrier, and modulating gut microbiota is developed by electrostatically adsorbing diallyl trisulfide-loaded peptide dendrimer nanogels (DATS@PDNs, abbreviated as DPs) onto the montmorillonite (MMT) surface. Upon rectal administration, DPs@MMT specifically binds to and covers the damaged mucosa, promoting the accumulation and subsequent internalization of DPs by activated immune cells in the IBD site. DPs release H2S intracellularly in response to glutathione, initiating multiple therapeutic effects. In vitro and in vivo studies have shown that DPs@MMT effectively alleviates colitis by eliminating reactive oxygen species (ROS), inhibiting inflammation, repairing the mucosal barrier, and eradicating pathogens. RNA sequencing revealed that DPs@MMT exerts significant immunoregulatory and mucosal barrier repair effects, by activating pathways such as Nrf2/HO-1, PI3K-AKT, and RAS/MAPK/AP-1, and inhibiting the p38/ERK MAPK, p65 NF-κB, and JAK-STAT3 pathways, as well as glycolysis. 16S rRNA sequencing demonstrated that DPs@MMT remodels the gut microbiota by eliminating pathogens and increasing probiotics. This study develops a promising nanoformulation for IBD management.

Investigating the Combined Toxicity of Cu(II) and Carbon Monoxide (CO); Cellular CO Delivery Using a Cu(II) Flavonolato Complex

Carbon monoxide (CO) delivery molecules are of significant current interest as potential therapeutics, including for anticancer applications. A recent approach toward generating new types of materials-based anticancer agents involves combining the Fenton reactivity of a redox active metal ion with CO delivery. However, small molecule examples of these types of entities have not been systematically studied to evaluate the combined effect on cellular toxicity. Herein we describe a Cu(II) flavonolato complex which produces anticancer effects through a combination of copper-mediated reactive oxygen species (ROS) generation and light-induced flavonol CO release. Confocal microscopy studies provide evidence of enhanced flavonol uptake in the copper flavonolato system relative to the free flavonol, which leads to an increased amount of CO delivery within cells. Importantly, this work demonstrates that a metal flavonolato species can be used to produce enhanced toxicity effects resulting from both metal ion-induced Fenton reactivity and increased cellular uptake of a flavonol CO donor.

Piezoelectric Ba0.85 Sr0.15 TiO3 Nanosonosensitizer with Nitric Oxide Delivery for Boosting Cancer Therapy

The efficacy of sonodynamic therapy (SDT) mainly relies on the sonosensitizers, which generate reactive oxygen species (ROS) upon ultrasound (US) stimulation. However, the limited availability of high-efficiency sonosensitizers hampers the therapeutic effectiveness of SDT as a standalone modality. In this work, a robust sonodynamic and gas cancer therapeutic platform is constructed based on strontium (Sr) doped barium titanate (BST) piezoelectric nanoparticles functionalized with L-arginine (BST@LA). The doping of Sr into A site of the ABO3 piezoelectric nanocrystals not only introduces oxygen vacancies into the nanoparticles and enhance the intrinsic piezoelectricity, but also narrows the semiconductor band gap and enhances charge carrier migration, all of which facilitate the sonodynamic production of superoxide anion (•O2 - ) and hydroxyl radical (•OH). In addition, the generated ROS promotes the decomposition of the surface-tethered LA, enabling the controlled release of nitric oxide (NO) gas at the tumor site, thereby achieving a combination therapeutic effect. In vivo experiments exhibit remarkable tumor suppression rate (89.5%) in 4T1 tumor mice model, demonstrating the effectiveness of this strategy. The ion doping and oxygen vacancy engineering to improve sonosensitizers, along with the synergistic combination of sonodynamic and gas therapy, provides promising avenues for improving cancer therapy.

Simultaneous Light-Triggered Release of Nitric Oxide and Carbon Monoxide from a Lipid-Coated Upconversion Nanosystem Inhibits Colon Tumor Growth

Gas therapy has gained noteworthy attention in biomedical research, with the rise of gas-releasing molecules enhancing their therapeutic potential, especially when integrated into nano-based drug delivery systems. Herein, we present a lipid-coated gas delivery system to simultaneously shuttle two gas-releasing molecules carrying nitric oxide (NO) and carbon monoxide (CO), respectively. Upconversion nanoparticles (UCNPs) are designed to generate photons at 360 nm upon 808 nm of near-infrared (NIR) irradiation. These in situ-generated UV photons trigger simultaneous NO and CO release from S-nitrosoglutathione (GSNO) and the CO-releasing molecule (CORM), respectively, which are coloaded into lipid-coated UCNP/GSNO/CORM/FA nanoparticles (LUGCF). LUGCF with a GSNO/CORM mass ratio of 2:1 is determined to be optimal in terms of synergistically instigating apoptosis in HCT116 and CT26 colon cancer cells, where both NO/CO are released and subsequent production of ROS are detected. This CO/NO combination nanoplatform exhibits a very effective inhibition of colon tumor growth in vivo at relatively low doses upon a mild 808 nm irradiation. Overall, we effectively integrated two therapeutic gas-releasing molecules in one NIR-responsive nanosystem, presenting a promising therapeutic strategy for future biomedical applications in dual-gas cancer therapy.

Mechanisms and Application of Gas-Based Anticancer Therapies

Cancer is still one of the major factors threatening public health, with morbidity and mortality rates at the forefront of the world. Clinical drawbacks, such as high toxicity and side effects of drug therapy, and easy recurrence after surgery affect its therapeutic effect. Gas signaling molecules are essential in maintaining biological homeostasis and physiological functions as specific chemical substances for biological information transfer. In recent years, the physiological regulatory functions of gas molecules in the cancer process have been gradually revealed and have shown broad application prospects in tumor therapy. In this paper, standard gas therapies are classified and introduced. Taking H2, CO2, NO, CO, H2S, and SO2 gases as examples, the research progress and application of gas therapies in malignant tumors are mainly introduced in terms of biological characteristics, anticancer mechanisms, and treatment strategies. Finally, the problems and prospects for developing gases as anticancer drugs are outlined.

Local Drug Delivery Techniques for Triggering Immunogenic Cell Death

Immunogenic cell death (ICD), a dying state of the cells, encompasses the changes in the conformations of cell surface and the release of damage-associated molecular patterns, which could initiate an adaptive immune response by stimulating the dendritic cells to present antigens to T cells. Advancements in biomaterials, nanomedicine, and micro- and nano-technologies have facilitated the development of effective ICD inducers, but the potential toxicity of these vesicles encountered in drug delivery via intravenous administration hampers their further application. As alternatives, the local drug delivery systems have gained emerging attention due to their ability to prolong the retention of high payloads at the lesions, sequester drugs from harsh environments, overcome biological barriers to exert optimal efficacy, and minimize potential side effects to guarantee bio-safety. Herein, a brief overview of the local drug delivery techniques used for ICD inducers is provided, explaining how these techniques broaden, alter, and enhance the therapeutic capability while circumventing systemic toxicity at the same time. The historical context and prominent examples of the local administration of ICD inducers are introduced. The complexities, potential pitfalls, and opportunities for local drug delivery techniques in cancer immunotherapy are also discussed.

Gas-assisted phototherapy for cancer treatment

Phototherapies, mainly including photodynamic and photothermal therapy, have made considerable strides in the field of cancer treatment. With the aid of phototherapeutic agents, reactive oxygen species (ROS) or heat are generated under light irradiation to selectively damage cancer cells. However, sole-modality phototherapy faces certain drawbacks, such as limited penetration of phototherapeutic agents into tumor tissues, inefficient ROS generation due to hypoxia, treatment-induced inflammation and resistance of tumor to treatment (e.g., high levels of antioxidants, expression of heat shock protein). Gas therapy, an emerging therapy approach that damages cancer cells by improving the level of certain gas at the tumor site, shows potential to overcome the challenges associated with phototherapies. In addition, with the rapid development of nanotechnology, gas-assisted phototherapy based on nanomedicines has emerged as a promising strategy to enhance the treatment efficacy. This review summarizes recent advances in gas-assisted phototherapy and discusses the prospects and challenges of this strategy in cancer phototherapy.

Elimination of methicillin-resistant Staphylococcus aureus biofilms on titanium implants via photothermally-triggered nitric oxide and immunotherapy for enhanced osseointegration

BACKGROUND

Treatment of methicillin-resistant Staphylococcus aureus (MRSA) biofilm infections in implant placement surgery is limited by the lack of antimicrobial activity of titanium (Ti) implants. There is a need to explore more effective approaches for the treatment of MRSA biofilm infections.

METHODS

Herein, an interfacial functionalization strategy is proposed by the integration of mesoporous polydopamine nanoparticles (PDA), nitric oxide (NO) release donor sodium nitroprusside (SNP) and osteogenic growth peptide (OGP) onto Ti implants, denoted as Ti-PDA@SNP-OGP. The physical and chemical properties of Ti-PDA@SNP-OGP were assessed by scanning electron microscopy, X-ray photoelectron spectroscope, water contact angle, photothermal property and NO release behavior. The synergistic antibacterial effect and elimination of the MRSA biofilms were evaluated by 2',7'-dichlorofluorescein diacetate probe, 1-N-phenylnaphthylamine assay, adenosine triphosphate intensity, o-nitrophenyl-β-D-galactopyranoside hydrolysis activity, bicinchoninic acid leakage. Fluorescence staining, assays for alkaline phosphatase activity, collagen secretion and extracellular matrix mineralization, quantitative real‑time reverse transcription‑polymerase chain reaction, and enzyme-linked immunosorbent assay (ELISA) were used to evaluate the inflammatory response and osteogenic ability in bone marrow stromal cells (MSCs), RAW264.7 cells and their co-culture system. Giemsa staining, ELISA, micro-CT, hematoxylin and eosin, Masson's trichrome and immunohistochemistry staining were used to evaluate the eradication of MRSA biofilms, inhibition of inflammatory response, and promotion of osseointegration of Ti-PDA@SNP-OGP in vivo.

RESULTS

Ti-PDA@SNP-OGP displayed a synergistic photothermal and NO-dependent antibacterial effect against MRSA following near-infrared light irradiation, and effectively eliminated the formed MRSA biofilms by inducing reactive oxygen species (ROS)-mediated oxidative stress, destroying bacterial membrane integrity and causing leakage of intracellular components (P < 0.01). In vitro experiments revealed that Ti-PDA@SNP-OGP not only facilitated osteogenic differentiation of MSCs, but also promoted the polarization of pro-inflammatory M1 macrophages to the anti-inflammatory M2-phenotype (P < 0.05 or P < 0.01). The favorable osteo-immune microenvironment further facilitated osteogenesis of MSCs and the anti-inflammation of RAW264.7 cells via multiple paracrine signaling pathways (P < 0.01). In vivo evaluation confirmed the aforementioned results and revealed that Ti-PDA@SNP-OGP induced ameliorative osseointegration in an MRSA-infected femoral defect implantation model (P < 0.01).

CONCLUSIONS

These findings suggest that Ti-PDA@SNP-OGP is a promising multi-functional material for the high-efficient treatment of MRSA infections in implant replacement surgeries.

Ultrasound nanomedicine and materdicine

The conventional microbubble-based ultrasound biomedicine clinically plays a vital role in providing the dynamic detection of macro and microvasculature and disease theranostics. However, the intrinsic limitation of particle size severely decreases the treatment effectiveness due to their vascular transport characteristics, which promotes the development and application of multifunctional ultrasound-responsive nanomaterials. Herein, we put forward a research field of "ultrasound nanomedicine and materdicine", referring to the interdiscipline of ultrasound, nanobiotechnology and materials, which seeks to produce specific biological effects for addressing the challenges faced and dilemma of conventional ultrasound medicine. We comprehensively summarize the state-of-the-art scientific advances in the latest progress in constructing ultrasound-based platforms and ultrasound-activated sonosensitizers, ranging from the synthesis strategies, biological functions to ultrasound-triggered therapeutic applications. Ultimately, the unresolved challenges and clinical-translation potentials of ultrasound nanomedicine and materdicine are discussed and prospected in this evolving field.

Injectable thermo-sensitive hydrogel loaded hollow copper sulfide nanoparticles for ROS burst in TME and effective tumor treatment

Introduction: Lung cancer the most prevalent cause of cancer-related deaths, and current therapies lack sufficient specificity and efficacy. This study developed an injectable thermosensitive hydrogel harboring hollow copper sulfide nanoparticles and β-lapachone (Lap) (CLH) for lung tumor treatment. Methods: The hydrogel-encapsulated CLH system can remotely control the release of copper ions (Cu²⁺) and drugs using photothermal effects for non-invasive controlled-release drug delivery in tumor therapy. The released Cu²⁺ consumes the overexpressed GSH in TME and the generated Cu⁺ further exploits the TME characteristics to initiate nanocatalytic reactions for generating highly toxic hydroxyl radicals. In addition, in cancer cells overexpressing Nicotinamide adenine dinucleotide (phosphate): quinone oxidoreductase 1 (NQO1), Lap can catalyze the generation of hydrogen peroxide (H₂O₂) through futile redox cycles. H₂O₂ is further converted into highly toxic hydroxyl radicals via the Fenton-like reaction, leading to a burst of reactive oxygen species in TME, which further enhances the therapeutic effect of chemokines. Results: Analysis of the antitumor efficacy in a subcutaneous A549 lung tumor model mice showed a significant delay in tumor growth and no systemic toxicity was detected. Discussion: In conclusion, we have established a CLH nanodrug platform that enables efficient lung tumor therapy through combined photothermal/chemodynamic therapy (CDT) treatment and self-supplying H₂O₂ to achieve cascade catalysis, leading to explosive amplification of oxidative stress.

Lag Time in Diffusion-Controlled Release Formulations Containing a Drug-Free Outer Layer

Theoretical considerations along with extensive Monte Carlo simulations are used to calculate the lag time before the initiation of diffusion-controlled drug release in multilayer planar devices with an outer layer containing no drug. The presented results are also relevant in formulations coated by a drug-free membrane as well as in other reservoir systems. The diffusion of drug molecules through the outer layer towards the release medium is considered, giving rise to the observed lag time. We have determined the dependence of lag time on the thickness and the diffusion coefficient of the drug-free outer layer, as well as on the initial drug concentration and the surface area of the planar device. A simple expression, obtained through an analytical solution of diffusion equation, provides an approximate estimate for the lag time that describes the numerical results reasonably well; according to this relation, the lag time is proportional to the squared thickness of the outer layer over the corresponding diffusion coefficient and inversely proportional to the logarithm of the linear number density of the drug that is initially loaded in the inner layer.

Self-Powered, Implantable, and Wirelessly Controlled NO Generation System for Intracranial Neuroglioma Therapy

Gas therapy is an emerging technology for improving cancer therapy with high efficiency and low side effects. However, due to the existence of the gatekeeper of the blood-brain barrier (BBB) and the limited availability of current drug delivery systems, there still have been no reports on gas therapy for intracranial neuroglioma. Herein, an integrated, self-powered, and wirelessly controlled gas-therapy system is reported, which is composed of a self-powered triboelectric nanogenerator (TENG) and an implantable nitric oxide (NO) releasing device for intracranial neuroglioma therapy. In the system, the patient self-driven TENG converts the mechanical energy of body movements into electricity as a sustainable and self-controlled power source. When delivering energy to light a light-emitting diode in the implantable NO releasing device via wireless control, the encapsulated NO donor s-nitrosoglutathione (GSNO) can generate NO gas to locally kill the glioma cells. The efficacy of the proof-of-concept system in subcutaneous 4T1 breast cancer model in mice and intracranial glioblastoma multiforme in rats is verified. This self-powered gas-therapy system has great potential to be an effective adjuvant treatment modality to inhibit tumor growth, relapse, and invasion via teletherapy.

Photo-controlled and photo-calibrated nanoparticle enabled nitric oxide release for anti-bacterial and anti-biofilm applications

After numerous efforts to elucidate the biological role of nitric oxide (NO), NO treatments have become a hotspot at the forefront of medicine. NO-releasing substances are constantly needed, while the direct use of NO gas is unattainable in bio-systems. An ideal NO donor should possess controllable and visible NO-release capability. The reported NO donating nanoparticles, prepared via encapsulating a hydrophobic NO-releasing compound into DSPE-PEG₂₀₀₀, meet the criteria mentioned previously. The localization and flux of NO released from these nanoparticles could be manipulated by UV or blue light. Meanwhile, NOD-NPs emit a dose-dependent fluorescence intensity to calibrate the generation of NO. While the good biocompatibility of NOD-NPs has been validated, the NO from our nanoparticles demonstrates efficient anti-bacterial and anti-biofilm effects toward Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). Therefore, the NOD-NPs developed in this work have potential application in evaluating the regulation of microbes by NO.

Reactive Species-Activatable AIEgens for Biomedical Applications

Precision medicine requires highly sensitive and specific diagnostic strategies with high spatiotemporal resolution. Accurate detection and monitoring of endogenously generated biomarkers at the very early disease stage is of extensive importance for precise diagnosis and treatment. Aggregation-induced emission luminogens (AIEgens) have emerged as a new type of excellent optical agents, which show great promise for numerous biomedical applications. In this review, we highlight the recent advances of AIE-based probes for detecting reactive species (including reactive oxygen species (ROS), reactive nitrogen species (RNS), reactive sulfur species (RSS), and reactive carbonyl species (RCS)) and related biomedical applications. The molecular design strategies for increasing the sensitivity, tuning the response wavelength, and realizing afterglow imaging are summarized, and theranostic applications in reactive species-related major diseases such as cancer, inflammation, and vascular diseases are reviewed. The challenges and outlooks for the reactive species-activatable AIE systems for disease diagnostics and therapeutics are also discussed. This review aims to offer guidance for designing AIE-based specifically activatable optical agents for biomedical applications, as well as providing a comprehensive understanding about the structure-property application relationships. We hope it will inspire more interesting researches about reactive species-activatable probes and advance clinical translations.