Treating Multi-Drug-Resistant Bacterial Infections by Functionalized Nano-Bismuth Sulfide through the Synergy of Immunotherapy and Bacteria-Sensitive Phototherapy.

Owing to its flexibility and high treatment efficiency, phototherapy is rapidly emerging for treating bacteria-induced diseases, but how to improve the sensitivity of bacteria to reactive oxygen species (ROS) and heat simultaneously to kill bacteria under mild conditions is still a challenge. Herein, we designed a NIR light catalyst (Bi2S3-S-nitrosothiol-acetylcholine (BSNA)) by transforming •O2- into peroxynitrite in situ, which can enhance the bacterial sensibility to ROS and heat and kill bacteria under a mild temperature. The transformed peroxynitrite in situ possessed a stronger ability to penetrate cell membranes and antioxidant capacity. The BSNA nanoparticles (NPs) inhibited the bacterial glucose metabolic process through down-regulated xerC/xerD expression and disrupted the HSP70/HSP90 secondary structure through nitrifying TYR179. Additionally, the synergistic effect of the designed BSNA and clinical antibiotics increased the antibacterial activity. In the case of tetracycline-class antibiotics, BSNA NPs induced phenolic hydroxyl group structure changes and inhibited the interaction between tetracycline and targeted t-RNA recombinant protein. Besides, BSNA stimulated production of more CD8+ T cells and reduced common complications in peritonitis, which provided immunotherapy activity. The targeted and anti-infective effect of BSNA suggested that we propose a nanotherapeutic strategy to achieve more efficient synergistic therapy under mild temperatures.

Microwave assisted antibacterial action of Garcinia nanoparticles on Gram-negative bacteria.

Owing to the existence of the outer membrane barrier, most antibacterial agents cannot penetrate Gram-negative bacteria and are ineffective. Here, we report a general method for narrow-spectrum antibacterial Garcinia nanoparticles that can only be effective to kill Gram-positive bacteria, to effectively eliminate Gram-negative bacteria by creating transient nanopores in bacterial outer membrane to induce drug entry under microwaves assistance. In vitro, under 15 min of microwaves irradiation, the antibacterial efficiency of Garcinia nanoparticles against Escherichia coli can be enhanced from 6.73% to 99.48%. In vivo, MV-assisted GNs can effectively cure mice with bacterial pneumonia. The combination of molecular dynamics simulation and experimental results reveal that the robust anti-E. coli effectiveness of Garcinia nanoparticles is attributed to the synergy of Garcinia nanoparticles and microwaves. This work presents a strategy for effectively treating both Gram-negative and Gram-positive bacteria co-infected pneumonia using herbal medicine nanoparticles with MV assistance as an exogenous antibacterial auxiliary.

Photo-Sono Interfacial Engineering Exciting the Intrinsic Property of Herbal Nanomedicine for Rapid Broad-Spectrum Bacteria Killing.

Large doses and long duration are often required for herbal medicines to kill bacteria effectively. Herein, a photoacoustic interfacial engineering strategy was utilized to endow curcumin (Cur, a kind of herbal medicine) with rapid and highly effective bacteria-killing efficacy, in which Cur was combined with CuS to form a hybrid material of CuS/Cur with tight contact through in situ nucleation and growth on the petaloid CuS surface. Due to the different work functions of CuS and Cur, the interfacial electrons were redistributed, i.e., a large number of electrons gathered on the side of CuS. In contrast, the holes gathered on the side of Cur after contact. An internal electric field was formed to drive the excited electrons to transfer from CuS to Cur, thus enhancing the separation of electron-hole pairs. Besides exerting the drug nature of Cur itself, the CuS/Cur hybrid also had photo-sono responsive ability, which endowed the hybrid with photothermal, photodynamic, and sonodynamic effects. Therefore, this Cur-based hybrid killed 99.56% of Staphylococcus aureus and 99.48% of Escherichia coli under 808 nm near-infrared light irradiation and ultrasound successively for 15 min, which was ascribed to the synergy of ROS, hyperthermia, and released Cu2+ together with the drug properties of Cur. This work provides a strategy to enhance the therapeutic effects of herbal medicines against pathogenic bacterial infections by exciting the intrinsic properties of herbal medicines as materials through a photo-sono interfacial engineering strategy.

The recent progress on metal-organic frameworks for phototherapy.

Some infectious or malignant diseases such as cancers are seriously threatening the health of human beings all over the world. The commonly used antibiotic therapy cannot effectively treat these diseases within a short time, and also bring about adverse effects such as drug resistance and immune system damage during long-term systemic treatment. Phototherapy is an emerging antibiotic-free strategy to treat these diseases. Upon light irradiation, phototherapeutic agents can generate cytotoxic reactive oxygen species (ROS) or induce a temperature increase, which leads to the death of targeted cells. These two kinds of killing strategies are referred to as photodynamic therapy (PDT) and photothermal therapy (PTT), respectively. So far, many photo-responsive agents have been developed. Among them, the metal-organic framework (MOF) is becoming one of the most promising photo-responsive materials because its structure and chemical compositions can be easily modulated to achieve specific functions. MOFs can have intrinsic photodynamic or photothermal ability under the rational design of MOF construction, or serve as the carrier of therapeutic agents, owing to its tunable porosity. MOFs also provide feasibility for various combined therapies and targeting methods, which improves the efficiency of phototherapy. In this review, we firstly investigated the principles of phototherapy, and comprehensively summarized recent advances of MOF in PDT, PTT and synergistic therapy, from construction to modification. We expect that our demonstration will shed light on the future development of this field, and bring it one step closer to clinical trials.

Ultrasonic Interfacial Engineering of Red Phosphorous-Metal for Eradicating MRSA Infection Effectively.

Sonodynamic therapy (SDT) is considered to be a potential treatment for various diseases including cancers and bacterial infections due to its deep penetration ability and biosafety, but its SDT efficiency is limited by the hypoxia environment of deep tissues. This study proposes creating a potential solution, sonothermal therapy, by developing the ultrasonic interfacial engineering of metal-red phosphorus (RP), which has an obviously improved sonothermal ability of more than 20 °C elevation under 25 min of continuous ultrasound (US) excitation as compared to metal alone. The underlying mechanism is that the mechanical energy of the US activates the motion of the interfacial electrons. US-induced electron motion in the RP can efficiently transfer the US energy into phonons in the forms of heat and lattice vibrations, resulting in a stronger US absorption of metal-RP. Unlike the nonspecific heating of the cavitation effect induced by US, titanium-RP can be heated in situ when the US penetrates through 2.5 cm of pork tissue. In addition, through a sonothermal treatment in vivo, bone infection induced by multidrug-resistant Staphylococcus aureus (MRSA) is successfully eliminated in under 20 min of US without tissue damage. This work provides a new strategy for combating MRSA by strong sonothermal therapy through US interfacial engineering.

Ag3PO4 decorated black urchin-like defective TiO2 for rapid and long-term bacteria-killing under visible light.

Both phototherapy via photocatalysts and physical puncture by artificial nanostructures are promising substitutes for antibiotics when treating drug-resistant bacterial infectious diseases. However, the photodynamic therapeutic efficacy of photocatalysts is seriously restricted by the rapid recombination of photogenerated electron-hole pairs. Meanwhile, the nanostructures of physical puncture are limited to two-dimensional (2D) platforms, and they cannot be fully used yet. Thus, this research developed a synergistic system of Ag3PO4 nanoparticles (NPs), decorated with black urchin-like defective TiO2 (BU-TiO2-X/Ag3PO4). These NPs had a decreased bandgap compared to BU-TiO2-X, and BU-TiO2-X/Ag3PO4 (3:1) exhibited the lowest bandgap and the highest separation efficiency for photogenerated electron-hole pairs. After combination with BU-TiO2-X, the photostability of Ag3PO4 improved because the oxygen vacancy of BU-TiO2-X retards the reduction of Ag+ in Ag3PO4 into Ag0, thus reducing its toxicity. In addition, the nanospikes on the surface of BU-TiO2-X can, from all directions, physically puncture bacterial cells, thus assisting the hybrid's photodynamic therapeutic effects, alongside the small amount of Ag+ released from Ag3PO4. This achieves synergy, endowing the hybrid with high antibacterial efficacy of 99.76 ± 0.15% and 99.85 ± 0.09% against Escherichia coli and Staphylococcus aureus, respectively, after light irradiation for 20 min followed by darkness for 12 h. It is anticipated that these findings may bring new insight for developing synergistic treatment strategies against bacterial infectious diseases or pathogenic bacterial polluted environments.

Photoelectrons Mediating Angiogenesis and Immunotherapy through Heterojunction Film for Noninvasive Disinfection.

A light-inspired hydroxyapatite (Hap)/nitrogen-doped carbon dots (NCDs) modified graphene oxide (GO) heterojunction film is developed, which shows a promoted separation of interfacial electrons and holes and an inhibited recombination efficiency via hole depletion. The metabolism of bacteria on this film is significantly inhibited under light irradiation, due to the enhanced photocatalytic and photothermal effects. In addition, the electron transfer from the plasmonic membrane to the GO/NCD/Hap film further inhibits the adenosine triphosphate process of bacteria, thus leading to the synergetic antibacterial efficacy. Meanwhile, the electron transfer between film and cell membrane induces the Ca2+ flow after irradiation, which can promote the migration and proliferation of cells and alkaline phosphatase enhancement, thus favoring the tissue reconstruction. An in vivo test discloses that the vascular injury repair is achieved through the Ca2+-activated PLCγ1/ERK pathway, identified by the enhanced CD31 expression. Moreover, the increased CD4+/CD8+ lymphocytes are ameliorative by activating the PI3K/P-AKT pathway. Consequently, the electron transfer boosts the synergic photodynamic and photothermal therapeutic effects for bacterial infection by Ca2+ flow for immunotherapy. This mild phototherapy approach with GO/NCDs/Hap, which can simultaneously repair injured vessels and relieve inflammation reactions, will increase the clinical application of noninvasive phototherapy in the near future.

Treatment of MRSA-infected osteomyelitis using bacterial capturing, magnetically targeted composites with microwave-assisted bacterial killing.

Owing to the poor penetration depth of light, phototherapy, including photothermal and photodynamic therapies, remains severely ineffective in treating deep tissue infections such as methicillin-resistant Staphylococcus aureus (MRSA)-infected osteomyelitis. Here, we report a microwave-excited antibacterial nanocapturer system for treating deep tissue infections that consists of microwave-responsive Fe3O4/CNT and the chemotherapy agent gentamicin (Gent). This system, Fe3O4/CNT/Gent, is proven to efficiently target and eradicate MRSA-infected rabbit tibia osteomyelitis. Its robust antibacterial effectiveness is attributed to the precise bacteria-capturing ability and magnetic targeting of the nanocapturer, as well as the subsequent synergistic effects of precise microwaveocaloric therapy from Fe3O4/CNT and chemotherapy from the effective release of antibiotics in infection sites. The advanced target-nanocapturer of microwave-excited microwaveocaloric-chemotherapy with effective targeting developed in this study makes a major step forward in microwave therapy for deep tissue infections.

Near-Infrared Light Triggered Phototherapy and Immunotherapy for Elimination of Methicillin-Resistant Staphylococcus aureus Biofilm Infection on Bone Implant.

Clinically, methicillin-resistant Staphylococcus aureus (MRSA) biofilm infection inevitably induces the failure of bone implants. Herein, a hydrophilic and viscous hydrogel of poly(vinyl alcohol) modified with chitosan, polydopamine, and NO release donor was formed on a red phosphorus nanofilm deposited on a titanium implant (Ti-RP/PCP/RSNO). Under the irradiation of near-infrared light (NIR), peroxynitrite (•ONOO-) was formed by the reaction between the released NO and superoxide (•O2-) produced by the RP nanofilm. Specifically, we revealed the antibacterial mechanism of the ONOO- against the MRSA biofilm. In addition, osteogenic differentiation was promoted and inflammatory polarization was regulated by the released NO without NIR irradiation through upregulating the expression of Opn and Ocn genes and TNF-α. The MRSA biofilm was synergistically eradicated by •ONOO-, hyperthermia, and •O2- under NIR irradiation as well as the immunoreaction of the M1 polarization. The in vivo results also confirmed the excellent osteogenesis and biofilm eradication by released NO from the RP/PCP/RSNO system under NIR irradiation, indicating the noninvasive tissue reconstruction of MRSA-infected tissues through phototherapy and immunotherapy.

Zn2+-assisted photothermal therapy for rapid bacteria-killing using biodegradable humic acid encapsulated MOFs.

Bacterial infection is seriously threatening human health all over the world, especially with the emergence of increasing drug-fast bacteria. It is urgent to develop a drug-free strategy to kill bacteria rapidly and efficiently. In this work, humic acid (HuA) encapsulated zeolitic imidazole framework-8 (ZIF-8) (HuA@ZIF-8) nanocomposites are synthesized by the in-situ growth of ZIF-8 on the surface of polyvinylpyrrolidone (PVP)-modified HuA. The synthesized nanocomposites possesses good photothermal effects, i.e., the temperature increased to 59.4 °C under the particle concentration of 1000 µg/mL with 10 min NIR irradiation. In addition, NIR irradiation can also control the release of Zn2+ from the composites. The good photothermal effects originate from HuA that can effectively absorb NIR light. The controlled release of Zn2+ is ascribed to the induced-dissociation of ZIF-8 under NIR light irradiation. The synergistic action of photothermal therapy and release of zinc ions contributes to the excellent antibacterial efficiency of HuA@ZIF-8 within a short time, i.e. 99.59 % and 99.37 % against Staphylococcus aureus and Escherichia coli with 20 min NIR irradiation, respectively. This work provides a promising strategy to develop a light-responsive platform with good biodegradability and low cost for rapid and effective sterilization.

Highly Effective and Noninvasive Near-Infrared Eradication of a Staphylococcus aureus Biofilm on Implants by a Photoresponsive Coating within 20 Min.

Biofilms have been related to the persistence of infections on medical implants, and these cannot be eradicated because of the resistance of biofilm structures. Therefore, a biocompatible phototherapeutic system is developed composed of MoS2, IR780 photosensitizer, and arginine-glycine-aspartic acid-cysteine (RGDC) to safely eradicate biofilms on titanium implants within 20 min. The magnetron-sputtered MoS2 film possesses excellent photothermal properties, and IR780 can produce reactive oxygen species (ROS) with the irradiation of near-infrared (NIR, λ = 700-1100 nm) light. Consequently, the combination of photothermal therapy (PTT) and photodynamic therapy (PDT), assisted by glutathione oxidation accelerated by NIR light, can provide synergistic and rapid killing of bacteria, i.e., 98.99 ± 0.42% eradication ratio against a Staphylococcus aureus biofilm in vivo within 20 min, which is much greater than that of PTT or PDT alone. With the assistance of ROS, the permeability of damaged bacterial membranes increases, and the damaged bacterial membranes become more sensitive to heat, thus accelerating the leakage of proteins from the bacteria. In addition, RGDC can provide excellent biosafety and osteoconductivity, which is confirmed by in vivo animal experiments.

Lysozyme-Assisted Photothermal Eradication of Methicillin-Resistant Staphylococcus aureus Infection and Accelerated Tissue Repair with Natural Melanosome Nanostructures.

Patients often face the challenge of antibiotic-resistant bacterial infections and lengthy tissue reconstruction after surgery. Herein, human hair-melanosome derivatives (HHMs), comprising keratins and melanins, are developed using a simple "low-temperature alkali heat" method for potentially personalized therapy. The mulberry-shaped HHMs have an average width of ∼270 nm and an average length of ∼700 nm, and the negatively charged HHMs can absorb positively charged Lysozyme (Lyso) to form the HHMs-Lyso composites through electrostatic interaction. These naturally derived biodegradable nanostructures act as exogenous killers to eliminate methicillin-resistant Staphylococcus aureus (MRSA) infection with a high antibacterial efficacy (97.19 ± 2.39%) by synergistic action of photothermy and "Lyso-assisted anti-infection" in vivo. Additionally, HHMs also serve as endogenous regulators of collagen alpha chain proteins through the "protein digestion and absorption" signaling pathway to promote tissue reconstruction, which was confirmed by quantitative proteomic analysis in vivo. Notably, the 13 upregulated collagen alpha chain proteins in the extracellular matrix (ECM) after HHMs treatment demonstrated that keratin from HHMs in collagen-dependent regulatory processes serves as a notable contributor to augmented wound closure. The current paradigm of natural material-tissue interaction regulates the cell-ECM interaction by targeting cell signaling pathways to accelerate tissue repair. This work may provide insight into the protein-level pathways and the potential mechanisms involved in tissue repair.

Rapid and Superior Bacteria Killing of Carbon Quantum Dots/ZnO Decorated Injectable Folic Acid-Conjugated PDA Hydrogel through Dual-Light Triggered ROS and Membrane Permeability.

One of the most difficult challenges in the biomedical field is bacterial infection, which causes tremendous harm to human health. In this work, an injectable hydrogel is synthesized through rapid assembly of dopamine (DA) and folic acid (FA) cross-linked by transition metal ions (TMIs, i.e., Zn2+ ), which was named as DFT-hydrogel. Both the two carboxyl groups in the FA molecule and catechol in polydopamine (PDA) easily chelates Zn2+ to form metal-ligand coordination, thereby allowing this injectable hydrogel to match the shapes of wounds. In addition, PDA in the hydrogel coated around carbon quantum dot-decorated ZnO (C/ZnO) nanoparticles (NPs) to rapidly generate reactive oxygen species (ROS) and heat under illumination with 660 and 808 nm light, endows this hybrid hydrogel with great antibacterial efficacy against Staphylococcus aureus (S. aureus, typical Gram-positive bacteria) and Escherichia coli (E. coli, typical Gram-negative bacteria). The antibacterial efficacy of the prepared DFT-C/ZnO-hydrogel against S. aureus and E. coli under dual-light irradiation is 99.9%. Importantly, the hydrogels release zinc ions over 12 days, resulting in a sustained antimicrobial effect and promoted fibroblast growth. Thus, this hybrid hydrogel exhibits great potential for the reconstruction of bacteria-infected tissues, especially exposed wounds.

Peptide-Drug Conjugate-Based Nanocombination Actualizes Breast Cancer Treatment by Maytansinoid and Photothermia with the Assistance of Fluorescent and Photoacoustic Images.

To develop a highly efficient strategy against tumors, here, a nanocombination (PDC/P@HCuS) was designed and constructed to actualize chemo-phototherapy with the assistance of fluorescence (FL) and photoacoustic (PA) images. First, a type of organic-inorganic hybrid nanosystem (P@HCuS) was engineered by coupling the fluorescence-labeled amphiphilic fPEDC copolymer on the surface of hollow mesoporous copper sulfide nanoparticle (HCuS), in which HCuS was used as a photothermal and PA agent; fPEDC as a stabilizer, chromophore, and redox/pH-sensitive gatekeeper; and both of them as drug carriers. Then, a peptide-drug conjugate (cRGD-SMCC-DM1, PDC), as a molecular targeted maytansinoid, was loaded inside of P@HCuS to form PDC/P@HCuS. Next, the PDC/P@HCuS was investigated carefully with or without near-infrared (NIR) laser irradiation. In vitro, the nanocombination exhibited stimuli-responsive drug release, obvious cellular uptake, strong cytotoxicity to tumor cells, significant impact on cell cycle, and cytoskeleton and cellular proteomics as well as evident permeability into the tumor sphere, most of which could be boosted by NIR laser irradiation. In vivo, the nanocombinaiton exerted good FL/PA imaging features and photothermal efficiency, achieved the best antitumor efficacy in the presence of NIR laser irradiation, and showed excellent biosafety. Together, it demonstrated that the PDC/P@HCuS, representing a chemo-phototherapy based on a nanocombination associated with peptide-drug conjugate, could achieve the highly efficient antitumor effect.

Local Photothermal/Photodynamic Synergistic Therapy by Disrupting Bacterial Membrane To Accelerate Reactive Oxygen Species Permeation and Protein Leakage.

Bacterial infection is still a ticklish clinical challenge even though some advanced antibacterial materials and techniques have been put forward. This work reports that rapid and effective antibacterial performance is achieved by the synergistic local photothermal and photodynamic therapy (PTDT). Within 10 min of light irradiation, both Escherichia coli and Staphylococcus aureus are almost completely eliminated by the action of photothermy (52.1 °C) and limited reactive oxygen species (ROS), the corresponding bacterial killing efficiencies are 99.91 and 99.97%, respectively, which are far higher than single modal therapy, i.e., photothermal therapy or photodynamic therapy with antibacterial efficacy of 50 or 70%, respectively. The mechanism is that bacterial membrane permeation is increased by PTDT because photothermy shows more severe impact only on E. coli by destroying the outmost bacterial panniculus, whereas the inner panniculus of the two kinds of bacteria is more sensitive to ROS. Hence, ROS penetrates the bacterial membrane more easily, and meanwhile, the proteins in the bacteria are severely lost after the bacterial membrane disruption, which leads to bacterial death. In vivo results reveal that rapid and effective sterilization is an important process to accelerate wound healing, and the traumas on the rats' backbones heal well within 12 days by PTDT. Furthermore, the PTDT is friendly to major organs of rats during the therapeutic process. Therefore, the synergistic therapy system can be a safe therapeutic system for clinical sterilization with great potential. More importantly, the antibacterial mechanism presented in this work has great guiding significance for the design of other advanced antibacterial systems and techniques.

Enhancing the antibacterial efficacy of low-dose gentamicin with 5 minute assistance of photothermy at 50 °C.

Implant materials are prone to bacterial infections and cause serious consequences, while traditional antibiotic therapy has a long treatment cycle and even causes bacterial resistance. In this work, a photothermal therapy (PTT) assisted drug release system has been developed on the implant surface for in situ rapid disinfection under 808 nm light irradiation within a short time, in which gentamicin (Gent) is loaded by polyethylene glycol (PEG) modified molybdenum disulfide (MoS2) on Ti surface, and then encapsulated with chitosan (CS) (CS/Gent/PEG/MoS2-Ti). The hyperthermia produced by the coatings irradiated by 808 nm near-infrared (NIR) light can not only accelerate the local release of Gent, but also reduce the activity of bacteria, which makes it easy for these locally released drugs to enter the interior of the bacteria to inhibit the protein synthesis and destroy the cell membrane. When maintained at 50 °C for 5 min under NIR irradiation, this system can achieve an antibacterial efficacy of 99.93% and 99.19% against Escherichia coli and Staphylococcus aureus, respectively. By contrast, even after treatment for 120 min, only a 93.79% antibacterial ratio can be obtained for Gent alone. This is because hyperthermia produced from the coatings during irradiation can assist antibiotics in killing bacteria in a short time. Even under a low dose of 2 µg mL-1, the photothermal effect assisted gentamicin can achieve an antibacterial efficacy of 96.86% within 5 min. In vitro cell culture shows that the modified surface can facilitate cell adhesion, spreading and proliferation. The 7 day subcutaneous infection model confirms that the prepared surface system can exhibit a much faster sterilization and tissue reconstruction than the control group with light assistance. Compared with the traditional drug release system, this photothermy controlled drug-loaded implant surface system can not only provide rapid and high-efficiency in situ sterilization, but also offer long-term prevention of local bacterial infection.