We have investigated the interaction between long circulating poly(ethylene glycol)-stabilized single-walled carbon nanotubes (SWNTs) and the complement system. Aminopoly(ethylene glycol)(5000)-distearoylphosphatidylethanolamine (aminoPEG(5000)-DSPE) and methoxyPEG(5000)-DSPE coated as-grown HIPco SWNTs activated complement in undiluted normal human serum as reflected in significant rises in C4d and SC5b-9 levels, but not the alternative pathway split-product Bb, thus indicating activation exclusively through C4 cleavage. Studies in C2-depleted serum confirmed that PEGylated nanotube-mediated elevation of SC5b-9 was C4b2a convertase-dependent. With the aid of monoclonal antibodies against C1s and human serum depleted from C1q, nanotube-mediated complement activation in C1q-depleted serum was also shown to be independent of classical pathway. Nanotube-mediated C4d elevation in C1q-depleted serum, however, was inhibited by N-acetylglucosamine, Futhan (a broad-spectrum serine protease inhibitor capable of preventing complement activation through all three pathways) and anti-MASP-2 antibodies; this strongly suggests a role for activation of MASP-2 in subsequent C4 cleavage and assembly of C4b2a covertases. Intravenous injection of PEGylated nanotubes in some rats was associated with a significant rise in plasma thromboxane B2 levels, indicative of in vivo nanotube-mediated complement activation. The clinical implications of these observations are discussed.

Single-walled carbon nanotubes (SWNTs) with various unique properties have attracted great attention in cancer theranostics. Herein, SWNTs are coated with a shell of polydopamine (PDA), which is further modified by polyethylene glycol (PEG). The PDA shell in the obtained SWNT@PDA-PEG could chelate Mn(2+), which together with metallic nanoparticulate impurities anchored on SWNTs offer enhanced both T1 and T2 contrasts under magnetic resonance (MR) imaging. Meanwhile, also utilizing the PDA shell, radionuclide (131)I could be easily labeled onto SWNT@PDA-PEG, enabling nuclear imaging and radioisotope cancer therapy. As revealed by MR & gamma imaging, efficient tumor accumulation of SWNT@PDA-(131)I-PEG is observed after systemic administration into mice. By further utilizing the strong near-infarared (NIR) absorbance of SWNTs, NIR-triggered photothermal therapy in combination with (131)I-based radioisotope therapy is realized in our animal experiments, in which a remarkable synergistic antitumor therapeutic effect is observed compared to monotherapies. Our work not only presents a new type of theranostic nanoplatform based on SWNTs, but also suggests the promise of PDA coating as a general approach to modify nano-agents and endow them with highly integrated functionalities.

Metal hydrides have been rarely used in biomedicine. Herein, we fabricate titanium hydride (TiH1.924) nanodots from its powder form via the liquid-phase exfoliation, and apply these metal hydride nanodots for effective cancer treatment. The liquid-phase exfoliation is an effective method to synthesize these metal hydride nanomaterials, and its efficiency is determined by the matching of surface energy between the solvent and the metal hydrides. The obtained TiH1.924 nanodots can produce reactive oxygen species (ROS) under ultrasound, presenting a highly efficient sono-sensitizing effect. Meanwhile, TiH1.924 nanodots with strong near-infrared (NIR) absorbance can serve as a robust photothermal agent. By using the mild photothermal effect to enhance intra-tumoral blood flow and improve tumor oxygenation, a remarkable synergistic therapeutic effect is achieved in the combined photothermal-sonodynamic therapy. Importantly, most of these TiH1.924 nanodots can be cleared out from the body. This work presents the promises of functional metal hydride nanomaterials for biomedical applications.

Reactive oxygen species (ROS) play vital roles in intestinal inflammation. Therefore, eliminating ROS in the inflammatory site by antioxidant enzymes such as catalase and superoxide dismutase may effectively curb inflammatory bowel disease (IBD). Here, Escherichia coli Nissle 1917 (ECN), a kind of oral probiotic, was genetically engineered to overexpress catalase and superoxide dismutase (ECN-pE) for the treatment of intestinal inflammation. To improve the bioavailability of ECN-pE in the gastrointestinal tract, chitosan and sodium alginate, effective biofilms, were used to coat ECN-pE via a layer-by-layer electrostatic self-assembly strategy. In a mouse IBD model induced by different chemical drugs, chitosan/sodium alginate coating ECN-pE (ECN-pE(C/A)2) effectively relieved inflammation and repaired epithelial barriers in the colon. Unexpectedly, such engineered EcN-pE(C/A)2 could also regulate the intestinal microbial communities and improve the abundance of Lachnospiraceae_NK4A136 and Odoribacter in the intestinal flora, which are important microbes to maintain intestinal homeostasis. Thus, this study lays a foundation for the development of living therapeutic proteins using probiotics to treat intestinal-related diseases.

Wound microenvironment with excess reactive oxygen species (ROS) can significantly inhibit wound healing. Encouraged by hydrogen molecules (H2 ) with effective ROS scavenging and calcium hydride (CaH2 ) with sufficient H2 supply, the authors for the first time employed CaH2 as a therapeutic H2 donor and starch as a diluent to construct CaH2 pulvis dressing for wound healing treatment. It has been found that CaH2 by generating H2 exhibited excellent ROS scavenging performance, favorable for preserving the oxidative-stress-induced cell death. After being applied onto the skin wound, the CaH2 pulvis dressing with the unique ROS-scavenging ability can accelerate skin wound healing in healthy/diabetic mice (small animal models) and Bama mini-pigs (large animal model). Such CaH2 dressing can release H2 to relieve the inflammation levels, decrease the secretion of pro-inflammatory cytokines, increase the infiltration of inflammation-suppressive immune cells, and promote the regeneration of new blood vessels and collagens, thereby accelerating wound healing. This work highlighted that the integration of anti-oxidation and anti-inflammation functions based on CaH2 dressing endowed it with a promising possibility for the treatment of inflammatory diseases.

Tumor ablation therapies provide a minimally invasive approach to treat cancer. However, inhibition of cancer metastasis and recurrence after ablation is still a challenge in clinical trials. Here, we propose a strategy using combinatorial thermal ablation, adjuvants and immune checkpoint blockade (ICB) to inhibit metastatic tumor and recurrence via antitumor immune responses post tumor thermal ablation, which are frequently used in the clinic. Furthermore, a strong immune memory against cancer was observed 80 days after the primary tumor was ablated. Considering that all components in our design are approved by Food and Drug Administration (FDA), we provide a strategy based on clinically used cancer treatment technique that is promising in clinical translation.

Hydrogen can be used as an anti-cancer treatment. However, the continuous generation of H2 molecules within the tumor is challenging. Magnesium (Mg) and its alloys have been extensively used in the clinic as implantable metals. Here we develop, by decorating platinum on the surface of Mg rods, a Mg-based galvanic cell (MgG), which allows the continuous generation of H2 in an aqueous environment due to galvanic-cell-accelerated water etching of Mg. By implanting MgG rods into a tumor, H2 molecules can be generated within the tumor, which induces mitochondrial dysfunction and intracellular redox homeostasis destruction. Meanwhile, the Mg(OH)2 residue can neutralize the acidic tumor microenvironment (TME). Such MgG rods with the micro-galvanic cell structure enable hydrogen therapy to inhibit the growth of tumors, including murine tumor models, patient-derived xenografts (PDX), as well as VX2 tumors in rabbits. Our research suggests that the galvanic cells for hydrogen therapy based on implantable metals may be a safe and effective cancer treatment.

Cancer immunotherapy using cancer vaccines has shown great potential in the prevention and treatment of cancer. Here, we report an implantable autologous blood clot scaffold for enhanced cancer vaccination. It comprises a gel-like fibrin network formed by coagulation of blood to trap a large number of red blood cells. Upon implantation, the cross-linked RBCs in the blood clot can attract and recruit a great number of immune cells, leading to the formation of an "immune niche." Encapsulated with tumor-associated antigen and adjuvant, the blood clot vaccine (BCV) can induce a robust anticancer immune response. The BCV combined with immune checkpoint blockade effectively inhibits tumor growth in B16F10 and 4T1 tumor models. The proposed implantable blood clot cancer vaccine can be readily made by mixing the blood from patients with cancer with immunomodulating agents ex vivo, followed by reimplantation into the same patient for personalized cancer immunotherapy in future clinical translation.

Starvation therapy to slow down the tumor growth by cutting off its energy supply has been proposed to be an alternative therapeutic strategy for cancer treatment. Herein, glucose oxidase (GOx) is loaded into stealth liposomes and act as the glucose and oxygen elimination agent to trigger the conversion of glucose and oxygen into gluconic acid and H2O2. Such liposome-GOx after intravenous injection with effective tumor retention is able to exhaust glucose and oxygen within the tumor, producing cytotoxic H2O2 and enhancing hypoxia, as vividly visualized by non-invasive in vivo photoacoustic imaging. By further combination treatment with stealth liposomes loaded with banoxantrone dihydrochloride (AQ4N), a hypoxia-activated pro-drug, a synergistically enhanced tumor growth inhibition effect is achieved in the mouse model of 4T1 tumor. Hence, by combining starvation therapy and hypoxia-activated therapy tactfully utilizing liposomal nanocarriers to co-deliver both enzymes and prodrugs, an innovative strategy is presented in this study for effective cancer treatment.

Cancer local physical therapy (PT) by using heat, cold, electrical stimulation, irradiation or ultrasound to treat tumor is accepted as alternative choice for cancer patients. However, local recurrence and metastasis after such treatments remains to be the major cause of treatment failure and mortality. Therefore, it is necessary to develop a therapeutic strategy to inhibit local recurrence and metastasis. Inspired by the excellent inflammatory targeting ability of platelets, here we expect that the monoclonal antibody against programmed-death ligand 1 (aPDL1) engineered platelets could inhibit tumor local recurrence effectively, by facilitating transport of anti-PD-L1 antibodies to the ablated area with residue tumors. Using triple-negative breast carcinomas (4T1) bearing mouse model, we proved that antibody-coupled platelets could effectively target incompletely ablated tumor with thermal ablation (TA). We found the release of anti-PD-L1 can be triggered upon the platelets activation, together with many pro-inflammatory cytokines. The release of anti-PD-L1 is likely due to the dissociation of platelets upon the activation. Our findings approved that our platelet-based platform could facilitate the delivery of immune checkpoint antibody to tumor residues and remarkably prevent tumor recurrence after ablation. Moreover, this platelet-based delivery strategy may be extended to the targeted delivery of therapeutics post other types of local therapies including photodynamic therapy, high-intensity-focused-ultrasound ablation therapy, and even radiotherapy.

Herein, an intelligent biodegradable hollow manganese dioxide (H-MnO2) nano-platform is developed for not only tumor microenvironment (TME)-specific imaging and on-demand drug release, but also modulation of hypoxic TME to enhance cancer therapy, resulting in comprehensive effects favoring anti-tumor immune responses. With hollow structures, H-MnO2 nanoshells post modification with polyethylene glycol (PEG) could be co-loaded with a photodynamic agent chlorine e6 (Ce6), and a chemotherapy drug doxorubicin (DOX). The obtained H-MnO2-PEG/C&D would be dissociated under reduced pH within TME to release loaded therapeutic molecules, and in the meantime induce decomposition of tumor endogenous H2O2 to relieve tumor hypoxia. As a result, a remarkable in vivo synergistic therapeutic effect is achieved through the combined chemo-photodynamic therapy, which simultaneously triggers a series of anti-tumor immune responses. Its further combination with checkpoint-blockade therapy would lead to inhibition of tumors at distant sites, promising for tumor metastasis treatment.MnO2 nanostructures are promising TME-responsive theranostic agents in cancer. Here, the authors develop a nano-platform based on hollow H-MnO2 nanoshells able to modulate the tissue microenvironment, release a drug and inhibit tumor growth alone or in combination with check-point blockade therapy.

A therapeutic strategy that can eliminate primary tumours, inhibit metastases, and prevent tumour relapses is developed herein by combining adjuvant nanoparticle-based photothermal therapy with checkpoint-blockade immunotherapy. Indocyanine green (ICG), a photothermal agent, and imiquimod (R837), a Toll-like-receptor-7 agonist, are co-encapsulated by poly(lactic-co-glycolic) acid (PLGA). The formed PLGA-ICG-R837 nanoparticles composed purely by three clinically approved components can be used for near-infrared laser-triggered photothermal ablation of primary tumours, generating tumour-associated antigens, which in the presence of R837-containing nanoparticles as the adjuvant can show vaccine-like functions. In combination with the checkpoint-blockade using anti-cytotoxic T-lymphocyte antigen-4 (CTLA4), the generated immunological responses will be able to attack remaining tumour cells in mice, useful in metastasis inhibition, and may potentially be applicable for various types of tumour models. Furthermore, such strategy offers a strong immunological memory effect, which can provide protection against tumour rechallenging post elimination of their initial tumours.

Rationale: Despite the promises of applying theranostic nanoagents for imaging-guided cancer therapy, the chronic retention of these nanoagents may cause safety concerns that hinder their future clinical applications. The metabolizable nanoagents with rapid renal excretion to avoid long-term toxicity is a possible solution for this issue. Method: Herein, we synthesize ultra-small metal-organic coordination polymer nanodots based on ruthenium ion (Ru3+) / phenanthroline (Phen) (Ru-Phen CPNs) with superior near-infrared (NIR) absorption. The size, photothermal conversion, cytotoxicity, photoacoustic imaging, in vivo & in vitro cancer treatment efficiency and biosafety are tested. Results: The size of the ultra-small Ru-Phen CPNs is 6.5 nm. The photothermal conversion efficiency is measured to be ~ 60.69 %, much higher than that of previously reported photothermal agents. The Ru-Phen CPNs could be employed for photoacoustic (PA, 808 nm) imaging-guided photothermal therapy (PTT, 808 nm, 0.5 W/cm2) with great performance. Notably, the intrinsic PA signals (808 nm) of Ru-Phen CPNs are observed in kidneys of treated mice, illustrating efficient renal clearance of those ultra-small CPNs. Moreover, the clearance of CPNs is further confirmed by detecting Ru levels in urine and feces. Conclusion: Our work presents a new type of ultra-small Ru-based CPNs with a record high photothermal conversion efficiency, efficient tumor retention after systemic administration, and rapid renal excretion to avoid long-term toxicity, promising for imaging-guided photothermal therapy.

Radiofrequency ablation (RFA) is clinically adopted to destruct solid tumors, but is often incapable of completely ablating large tumors and those with multiple metastatic sites. Here we develop a CaCO3-assisted double emulsion method to encapsulate lipoxidase and hemin with poly(lactic-co-glycolic acid) (PLGA) to enhance RFA. We show the HLCaP nanoreactors (NRs) with pH-dependent catalytic capacity can continuously produce cytotoxic lipid radicals via the lipid peroxidation chain reaction using cancer cell debris as the fuel. Upon being fixed inside the residual tumors post RFA, HLCaP NRs exhibit a suppression effect on residual tumors in mice and rabbits by triggering ferroptosis. Moreover, treatment with HLCaP NRs post RFA can prime antitumor immunity to effectively suppress the growth of both residual and metastatic tumors, also in combination with immune checkpoint blockade. This work highlights that tumor-debris-fueled nanoreactors can benefit RFA by inhibiting tumor recurrence and preventing tumor metastasis.

Microwave ablation (MWA) as a local tumor ablation strategy suffers from posttreatment tumor recurrence. Development of adjuvant biomaterials to potentiate MWA is therefore of practical significance. Here, the high concentration of Ca2+ fixed by alginate as Ca2+-surplus alginate hydrogel shows enhanced heating efficiency and restricted heating zone under microwave exposure. The high concentration of extracellular Ca2+ synergizes with mild hyperthermia to induce immunogenic cell death by disrupting intracellular Ca2+ homeostasis. Resultantly, Ca2+-surplus alginate hydrogel plus MWA can ablate different tumors on both mice and rabbits at reduced operation powers. This treatment can also elicit antitumor immunity, especially if synergized with Mn2+, an activator of the stimulation of interferon genes pathway, to suppress the growth of both untreated distant tumors and rechallenged tumors. This work highlights that in situ-formed metallo-alginate hydrogel could act as microwave-susceptible and immunostimulatory biomaterial to reinforce the MWA therapy, promising for clinical translation.

Erythrocytes or red blood cells (RBCs) represent a promising cell-mediated drug delivery platform due to their inherent biocompatibility. Here, we developed an antigen delivery system based on the nanoerythrosomes derived from RBCs, inspired by the splenic antigen-presenting cell targeting capacity of senescent RBCs. Tumor antigens were loaded onto the nanoerythrosomes by fusing tumor cell membrane-associated antigens with nanoerythrosomes. This tumor antigen-loaded nanoerythrosomes (nano-Ag@erythrosome) elicited antigen responses in vivo and, in combination with the anti-programmed death ligand 1 (PD-L1) blockade, inhibited the tumor growth in B16F10 and 4T1 tumor models. We also generated a tumor model showing that "personalized nano-Ag@erythrosomes" could be achieved by fusing RBCs and surgically removed tumors, which effectively reduced tumor recurrence and metastasis after surgery.

The limited penetration depth of external excitation light would remarkably impair the therapeutic efficacy of photodynamic therapy (PDT) and its clinical utilization. Herein, we engineered bioluminescent bacteria by transforming attenuated Salmonella typhimurium strain ΔppGpp (S.T.ΔppGpp) with firefly-luciferase-expressing plasmid (Luc-S.T.ΔppGpp) as an internal light source to evenly illuminate whole tumors. Upon being fixed inside tumors with in-situ formed hydrogel, the colonized Luc-S.T.ΔppGpp together with D-luciferin could continuously generate light to excite photosensitizer chlorin e6 (Ce6), leading to effective suppression of different types of tumors including opaque melanoma and large rabbit tumors. Such bioluminescence-triggered PDT presented significant advantages over conventional PDT excited with an external 660-nm light, which at a much high light energy could only slightly retard the growth of small subcutaneous tumors. Furthermore, we uncovered that Luc-S.T.ΔppGpp boosted PDT could also elicit potent antitumor immunity post the treatment to inhibit tumor metastasis and prevent tumor challenge. Therefore, this work highlights that such bioluminescent bacteria boosted PDT is a general and highly effective therapeutic approach toward diverse cancers with varying light-absorbing capacities and tumor sizes, promising for potential clinical translation because of their acceptable safety profiles.

The global coronavirus disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome (SARS)-like coronavirus (SARS-CoV-2), presents an urgent health crisis. More recently, an increasing number of mutated strains of SARS-CoV-2 have been identified globally. Such mutations, especially those on the spike glycoprotein to render its higher binding affinity to human angiotensin-converting enzyme II (hACE2) receptors, not only resulted in higher transmission of SARS-CoV-2 but also raised serious concerns regarding the efficacies of vaccines against mutated viruses. Since ACE2 is the virus-binding protein on human cells regardless of viral mutations, we design hACE2-containing nanocatchers (NCs) as the competitor with host cells for virus binding to protect cells from SARS-CoV-2 infection. The hACE2-containing NCs, derived from the cellular membrane of genetically engineered cells stably expressing hACE2, exhibited excellent neutralization ability against pseudoviruses of both wild-type SARS-CoV-2 and the D614G variant. To prevent SARS-CoV-2 infections in the lung, the most vulnerable organ for COVID-19, we develop an inhalable formulation by mixing hACE2-containing NCs with mucoadhesive excipient hyaluronic acid, the latter of which could significantly prolong the retention of NCs in the lung after inhalation. Excitingly, inhalation of our formulation could lead to potent pseudovirus inhibition ability in hACE2-expressing mouse model, without imposing any appreciable side effects. Importantly, our inhalable hACE2-containing NCs in the lyophilized formulation would allow long-term storage, facilitating their future clinical use. Thus, this work may provide an alternative tactic to inhibit SARS-CoV-2 infections even with different mutations, exhibiting great potential for treatment of the ongoing COVID-19 epidemic.

Ferroptosis is a recently identified regulated cell death pathway featured in iron prompted lipid peroxidation inside cells and found to be an effective approach to suppress tumor growth. Motived by the high efficacy of ferrous ions (Fe2+) in initiating intracellular lipid peroxidation via the Fenton reaction, this study herein prepares a pH-responsive Fe2+ delivery nanocarrier by coating calcium carbonate (CaCO3) nanoparticles with a metal-polyphenol coordination polymer composed of gallic acid (GA) and Fe2+. Together with simultaneous encapsulation of succinic acid conjugated cisplatin prodrugs (Pt(IV)-SA) and Fe2+, the yielded nanoparticles, coined as PGFCaCO3, are synthesized and exhibit uniform hollow structure. After PEGylation, the resulted PGFCaCO3-PEG shows increased physiological stability and pH-dependent decomposition, drug release and catalytic capability in initiating lipid peroxidation. After being endocytosed, PGFCaCO3-PEG effectively promoted intracellular generation of cytotoxic reactive oxygen species including lipid peroxide, thereby exhibited superior inhibition effect towards both murine 4T1 and CT26 cancer cells over Pt(IV)-SA and GFCaCO3-PEG. As a result, treatment with systemic administration of PGFCaCO3-PEG effectively suppressed 4T1 tumor growth via combined Fe2+ initiated ferroptosis and Pt(IV)-SA mediated chemotherapy. This work highlights that intracellular delivery of Fe2+ is a robust approach to enhance tumor chemotherapy by inducing ferroptosis.

Overexpression of P-glycoprotein (P-gp), which is responsible for pumping chemotherapeutic drugs out of tumor cells, has been recognized as an important cause of drug resistance in conventional chemotherapy. Herein, porous platinum nanoparticles (pPt NPs) are developed to enable the combined electrodynamic therapy (EDT) with chemotherapy. With polyethylene glycol (PEG) coating, the obtained pPt-PEG NPs could be loaded with anticancer drug doxorubicin (DOX) by utilizing the porous structure of pPt NPs. Those pPt-PEG NPs are able to produce reactive oxygen species (ROS) by triggering water decomposition under electric field, independent of O2 and H2O2 contents in the tumor. Furthermore, the ROS generated during EDT could induce the inhibition of P-glycoprotein (P-gp), in turn enhancing the efficacy of chemotherapeutic agents by facilitating intracellular accumulation of drugs. As the results, excellent synergetic therapeutic effects were observed by combining chemotherapy with EDT using DOX-loaded pPt (DOX@pPt-PEG) NPs, as demonstrated by both in vitro and in vivo experiments. This study demonstrates a new concept of combinational cancer therapy with superior therapeutic efficacy.