Synergistic Lysozyme‐Photodynamic Therapy Against Resistant Bacteria based on an Intelligent Upconversion Nanoplatform

Water soluble AIEgen-based thermosensitive and antibacterial hydroxypropyl chitin hydrogels for non-invasive visualization and wound healing

Antimicrobial hydrogels containing antibacterial agents have been extensively studied for postoperative infections, wound repair and tissue engineering. However, the abuse of antibiotics has led to the enhancement of bacterial resistance and traditional antibacterial agents are losing their effect. Therefore, fabricating novel and efficient antibacterial hydrogels with enhanced photodynamic antimicrobial activity, good biocompatibility, biodegradability and injectability are highly desirable for clinical application. Herein, a fluorescent and sunlight-triggered synergetic antibacterial thermosensitive hydrogel (red fluorescent hydroxypropyl chitin, redFHPCH) is constructed based on a new water-soluble AIEgen (aggregation-induced emission fluorogen) covalently introduced in hydroxypropyl chitin for non-invasive visualization and wound healing. The thermosensitive redFHPCH solution showing good injectability with fluidity at low temperature was completely transformed into hydrogel under body temperature. The in vitro and in vivo visualization and reactive oxygen species (ROS) generation of the redFHPCH hydrogel are demonstrated clearly because of its excellent AIE fluorescence imaging quality in the red/near-infrared region and superefficient ROS production by sunlight. Moreover, the redFHPCH hydrogel with positively charged quaternary ammonium groups displays a strong synergistic antibacterial effect for healing of infected wound under sunlight irradiation. We believe that this novel strategy can open a new door to explore diversified and multifunctional hydrogels for clinical application.

Construction of palladium porphyrins and triptycene photo-activated nanomaterial for enhanced colorimetric detection and inactivation of bacteria

In the face of increasing bacterial resistance, design of high-performing and dual-functional nanomaterials to satisfy the requirements for both detecting and eradicating bacteria is of immense importance, but still remains a great challenge. Herein, a hierarchically three-dimensional (3D) porous organic frameworks (PdPPOP_HBTT) was rationally designed and fabricated for the first time to realize ideal simultaneous detection and eradication of bacteria. PdPPOP_HBTT covalently integrated palladium 5,10,15,20-tetrakis-(4'-bromophenyl) porphyrin (PdTBrPP, an excellent photosensitizer) with 2,3,6,7,12,13-hexabromotriptycene (HBTT, a 3D building module). The resulting material had outstanding NIR absorption, narrow bad gap and robust singlet oxygen (¹O₂) production capacity, which is responsible for the sensitive detection and effective removal of bacteria. We successfully realized the colorimetric detection of S. aureus and the efficient removal of S. aureus and E. coli. The first-principles calculations found at the highly activated ¹O₂ derived from the 3D conjugated periodic structures and ample palladium adsorption site in PdPPOP_HBTT. The bacterial infection wound model revealed that PdPPOP_HBTT possesses good disinfection ability and negligible side effect to normal tissue in vivo. This finding provides an innovative strategy for designing individual porous organic polymer (POPs) with multi-function and also broaden the applications of POPs as powerful nonantibiotic type of antimicrobials.

Size-Controllable Nanosystem with Double Responsive for Deep Photodynamic Therapy

Photodynamic therapy (PDT) is a promising strategy for cancer treatment. However, a poor tissue penetration of activation light and low target specificity seriously hindered the clinical application of PDT. Here, we designed and constructed a size-controllable nanosystem (UPH) with inside-out responsive for deep PDT with enhanced biosafety. To obtain nanoparticles with the best quantum yield, a series of core-shell nanoparticles (UCNP@nPCN) with different thicknesses were synthesized by a layer-by-layer self-assembly method to incorporate a porphyritic porous coordination network (PCN) onto the surface of upconverting nanoparticles (UCNPs), followed by coating with hyaluronic acid (HA) on the surface of nanoparticles with optimized thickness to form the UPH nanoparticles. With the aid of HA, the UPH nanoparticles were capable of preferentially enriching in tumor sites and specific endocytosis by CD44 receptors as well as responsive degradation by hyaluronidase in cancer cells after intravenous administration. Subsequently, after being activated by strong penetrating 980 nm near-infrared light (NIR), the UPH nanoparticles efficiently converted oxygen into strongly oxidizing reactive oxygen species based on the fluorescence resonance energy transfer (FRET) effect, thereby significantly inhibiting tumor growth. Experimental results in vitro and in vivo indicated that such dual-responsive nanoparticles successfully realize the photodynamic therapy of deep-seated cancer with negligible side effects, which showed great potential for potential clinical translational research.

Oxygen-vacancy-rich molybdenum carbide MXene nanonetworks for ultrasound-triggered and capturing-enhanced sonocatalytic bacteria eradication

Incurable bacterial infection and intractable multidrug resistance remain critical challenges in public health. A prevalent approach against bacterial infection is phototherapy including photothermal and photodynamic therapy, which is unfortunately limited by low penetration depth of light accompanied with inevitable hyperthermia and phototoxicity damaging healthy tissues. Thus, eco-friendly strategy with biocompatibility and high antimicrobial efficacy against bacteria is urgently desired. Herein, we propose and develop an oxygen-vacancy-rich MoO_xin situ on fluorine-free Mo₂C MXene with unique neural-network-like structure, namely MoO_x@Mo₂C nanonetworks, in which their desirable antibacterial effectiveness originates from bacteria-capturing ability and robust reactive oxygen species (ROS) generation under precise ultrasound (US) irradiation. The high-performance, broad-spectrum microbicidal activity of MoO_x@Mo₂C nanonetworks without damaging normal tissues is validated based on systematic in vitro and in vivo assessments. Additionally, RNA sequencing analysis illuminates that the underlying bactericidal mechanism is attributed to the chaotic homeostasis and disruptive peptide metabolisms on bacteria instigated by MoO_x@Mo₂C nanonetworks under US stimulation. Considering antibacterial efficiency and a high degree of biosafety, we envision that the MoO_x@Mo₂C nanonetworks can serve as a distinct antimicrobial nanosystem to fight against diverse pathogenic bacteria, especially eradicating multidrug-resistant bacteria-induced deep tissue infection.

Highly biocompatible Ag nanocluster-reinforced wound dressing with long-term and synergistic bactericidal activity

Clinical application of antibiotic-free agents like silver nanoparticle-derived materials remains a critical challenge due to their limited long-term antibacterial activity and potential system toxicity. Herein, a highly biocompatible Ag nanocluster-reinforced hydrogel with enhanced synergistic antibacterial ability has been developed. Specifically, bioactive curcumin was incorporated into lysozyme-protected ultrasmall Ag nanoclusters (LC-AgNCs) and further integrated with sodium alginate (Sa) hydrogel (LC-AgNCs@Sa) through multiple interaction forces. Due to the synergistic antibacterial activity, LC-AgNCs could effectively kill both S. aureus and E. coli bacteria with a concentration down to 2.5 μg mL^-1. In-depth mechanism investigations revealed that the bactericidal effect of LC-AgNCs lies in their bacterial membrane destruction, reactive oxygen species (ROS) production, glutathione depletion and prooxidant-antioxidant system disruption ability. Curcumin can mediate the intracellular ROS balance to protect NIH 3T3 cells from oxidative stress and improve the biocompatibility of LC-AgNCs@Sa. LC-AgNCs@Sa with long-term antibacterial ability can effectively protect the wound from bacterial invasion in vivo, and significantly accelerate the wound healing process due to their distinctive functions of inhibiting inflammatory factor (TNF-α) production, promoting collagen deposit and facilitating re-epithelization. This study provides a new, versatile strategy for the design of high-performance antibacterial dressing for broad infectious disease therapy.

Lima K, Alves de Matos P, Tsubone TM, Gonçalves RR, Ferrari JL. Upconversion rare Earths nanomaterials applied to photodynamic therapy and bioimaging

Light-based therapies and diagnoses including photodynamic therapy (PDT) have been used in many fields of medicine, including the treatment of non-oncological diseases and many types of cancer. PDT require a light source and a light-sensitive compound, called photosensitizer (PS), to detect and destroy cancer cells. After absorption of the photon, PS molecule gets excited from its singlet ground state to a higher electronically excited state which, among several photophysical processes, can emit light (fluorescence) and/or generate reactive oxygen species (ROS). Moreover, the biological responses are activated only in specific areas of the tissue that have been submitted to exposure to light. The success of the PDT depends on many parameters, such as deep light penetration on tissue, higher PS uptake by undesired cells as well as its photophysical and photochemical characteristics. One of the challenges of PDT is the depth of penetration of light into biological tissues. Because photon absorption and scattering occur simultaneously, these processes depend directly on the light wavelength. Using PS that absorbs photons on "optical transparency windows" of biological tissues promises deeper penetration and less attenuation during the irradiation process. The traditional PS normally is excited by a higher energy photon (UV-Vis light) which has become the Achilles' heel in photodiagnosis and phototreatment of deep-seated tumors below the skin. Thus, the need to have an effective upconverter sensitizer agent is the property in which it absorbs light in the near-infrared (NIR) region and emits in the visible and NIR spectral regions. The red emission can contribute to the therapy and the green and NIR emission to obtain the image, for example. The absorption of NIR light by the material is very interesting because it allows greater penetration depth for in vivo bioimaging and can efficiently suppress autofluorescence and light scattering. Consequently, the penetration of NIR radiation is greater, activating the biophotoluminescent material within the cell. Thus, materials containing Rare Earth (RE) elements have a great advantage for these applications due to their attractive optical and physicochemical properties, such as several possibilities of excitation wavelengths - from UV to NIR, strong photoluminescence emissions, relatively long luminescence decay lifetimes (µs to ms), and high sensitivity and easy preparation. In resume, the relentless search for new systems continues. The contribution and understanding of the mechanisms of the various physicochemical properties presented by this system is critical to finding a suitable system for cancer treatment via PDT.

AIEgen Intercalated Nanoclay-Based Photodynamic/Chemodynamic Theranostic Platform for Ultra-Efficient Bacterial Eradication and Fast Wound Healing

With the emergence and global spread of bacterial resistance, pathogenic bacterial infections have become a serious threat to human health. Thus, therapeutic strategies with highly antibacterial efficacy and a low tendency to induce drug resistance are strongly desired to combat bacterial infections. Here, an ultra-efficient photodynamic/chemodynamic theranostics platform is developed by intercalating an aggregation-induced emission (AIE) photosensitizer, TPCI, into the nanolayers of iron-bearing montmorillonite (MMT). The formed TPCI/MMT composite can not only perform efficient photodynamic therapy (PDT) through a burst generation of singlet oxygen (¹O₂) upon white light illumination but also continuously implement chemodynamic therapy (CDT) by converting endogenous hydrogen peroxide into highly toxic hydroxyl radicals (^•OH) due to iron release. In addition, the fluorescence of TPCI/MMT can be activated due to the AIE feature of TPCI, which helps guide the location of the antimicrobials. The combination of such powerful bombs (PDT) and unremitting ambushes (CDT) in TPCI/MMT can synergistically and effectively eliminate bacteria and promote faster wound healing in vivo with good biocompatibility and low side effects. The smart and simple design of TPCI/MMT provides a representative paradigm for achieving efficient antimicrobials to combat the coming resistance crisis.

Upconversion nanomaterials and delivery systems for smart photonic medicines and healthcare devices

In the past decade, upconversion (UC) nanomaterials have been extensively investigated for the applications to photomedicines with their unique features including biocompatibility, near-infrared (NIR) to visible conversion, photostability, controllable emission bands, and facile multi-functionality. These characteristics of UC nanomaterials enable versatile light delivery for deep tissue biophotonic applications. Among various stimuli-responsive delivery systems, the light-responsive delivery process has been greatly advantageous to develop spatiotemporally controllable on-demand "smart" photonic medicines. UC nanomaterials are classified largely to two groups depending on the photon UC pathway and compositions: inorganic lanthanide-doped UC nanoparticles and organic triplet-triplet annihilation UC (TTA-UC) nanomaterials. Here, we review the current-state-of-art inorganic and organic UC nanomaterials for photo-medicinal applications including photothermal therapy (PTT), photodynamic therapy (PDT), photo-triggered chemo and gene therapy, multimodal immunotherapy, NIR mediated neuromodulations, and photochemical tissue bonding (PTB). We also discuss the future research direction of this field and the challenges for further clinical development.

808 nm NIR-triggered Camellia sapogein/curcumin based antibacterial upconversion nanoparticles for synergistic photodynamic-chemical combined therapy

Antibacterial upconversion nanoparticles (UCNP) based photodynamic-chemical combined therapy (UCNP-aPCCT) provides an ideal method to solve the antibiotic-resistant bacteria in deep-tissue infection. Saponin is a kind natural product exhibiting promising antibacterial...