Nm Near-infrared Light Research Articles

Ca-doping interfacial engineering and glycolysis enable rapid charge separation for efficient phototherapy of MRSA-infected wounds

Methicillin-resistant Staphylococcus aureus (MRSA) is the primary pathogenic agent responsible for epidermal wound infection and suppuration, seriously threatening the life and health of human beings. To address this fundamental challenge, we propose a heterojunction nanocomposite (Ca-CN/MnS) comprised of Ca-doped g-C3N4 and MnS for the therapy of MRSA-accompanied wounds. The Ca doping leads to a reduction in both the bandgap and the singlet state S1–triplet state T2 energy gap (ΔEST). The Ca doping also facilitates the two-photon excitation, thus remarkably promoting the separation and transfer of 808 nm near-infrared (NIR) light–triggered electron–hole pairs together with the built-in electric field. Thereby, the production of reactive oxygen species and heat are substantially augmented nearby the nanocomposite under 808 nm NIR light irradiation. Consequently, an impressive photocatalytic MRSA bactericidal efficiency of 99.98 ± 0.02 % is achieved following exposure to NIR light for 20 min. The introduction of biologically functional elements (Ca and Mn) can up-regulate proteins such as pyruvate kinase (PKM), L-lactate dehydrogenase (LDHA), and calcium/calmodulin-dependent protein kinase (CAMKII), trigger the glycolysis and calcium signaling pathway, promote cell proliferation, cellular metabolism, and angiogenesis, thereby expediting the wound-healing process. This heterojunction nanocomposite, with its precise charge-transfer pathway, represents a highly effective bactericidal and bioactive system for treating multidrug-resistant bacterial infections and accelerating tissue repair. Statement of significanceDue to the bacterial resistance, developing an antibiotic-free and highly effective bactericidal strategy to treat bacteria-infected wounds is critical. We have designed a heterojunction consisting of calcium doped g-C3N4 and MnS (Ca-CN/MnS) that can rapidly kill methicillin-resistant Staphylococcus aureus (MRSA) without damaging normal tissue through a synergistic effect of two-photon stimulated photothermal and photodynamic therapy. In addition, the release of trace amounts of biofunctional elements Mn and Ca triggers glycolysis and calcium signaling pathways that promote cellular metabolism and cell proliferation, contributing to tissue repair and wound healing.

Multiple therapeutic mechanisms of pyrrolic N-rich g-C3N4 nanosheets with enzyme-like function in the tumor microenvironment

Nanozyme-based synergistic catalytic therapies for tumors have attracted extensive research attention. However, the unsatisfactory efficiency and negative impact of the tumor microenvironment (TME) hinder its clinical applications. In this study, we provide an easy method to prepare transition metals loaded onto pyrrolic nitrogen-rich g-C3N4 (PN-g-C3N4) for forming metal-N4 sites. This N-rich material effectively transfers electrons from g-C3N4 to metal-N4 sites, promotes the oxidation–reduction reaction of metals with different valence states, and improves material reusability. Under TME conditions, copper ions loaded onto PN-g-C3N4 (Cu-PN-g-C3N4, CPC) can produce ·OH through a Fenton-like reaction for tumor inhibition. This Fenton-like reaction and tumor cell inhibition can be improved further by a photodynamic effect caused by light irradiation. We introduced upconversion nanoparticles (UCNPs) into CPC to obtain nano-enzymes (UCNPs@Cu-PN-g-C3N4, UCPC) for effectively penetrating the tissue, which emits light corresponding to the UV absorption region of CPC when excited with 980 nm near-infrared (NIR) light. The nanoplatform can reduce H2O2 concentration upon exposure to NIR light; this induces an increase in dissolved oxygen content and produces a higher supply of reactive oxygen species (ROS) for destroying tumor cells. Owing to the narrow bandgap (1.92 eV) of UCPC under 980 light irradiation, even under the condition of hypoxia, the excited electrons in the conduction band can reduce insoluble O2 through a single electron transfer process, thus effectively generating O2•–. Nanoenzyme materials with catalase properties produce three types of ROS (·OH, O2•– and 1O2) when realizing chemodynamic and photodynamic therapies. An excellent therapeutic effect was established by killing cells in vitro and the tumor-inhibiting effect in vivo, proving that the prepared nanoenzymes have an effective therapeutic effect and that the endogenous synergistic treatment of multiple treatment technologies can be realized.

A wettability-transformable superhydrophobic composite coating of hydroxyapatite/bismuth sulfide/lauric acid on AZ31B Mg alloy with dual-function of antibacterial and osteogenic properties

Recently, superhydrophobic magnesium (Mg)-based implants are attracting extensive interest due to their superior corrosion resistance and specific anti-bacterial adhesion characteristics. Nevertheless, the superhydrophobic surface is not conducive to cell adhesion and proliferation, which limits the application of superhydrophobic medical Mg alloys. Herein, the superhydrophobic composite coating of hydroxyapatite (HA)/bismuth sulfide (Bi2S3)/lauric acid (LA) was prepared on AZ31B Mg alloys via hydrothermal and impregnation methods, and the water contact angle of the composite coating was up to 156°, endowing Mg alloys with excellent corrosion resistance and antibacterial properties. Furthermore, the surface of the superhydrophobic coating can be transformed to hydrophilicity upon 808 nm near-infrared (NIR) light irradiation, due to the photothermal effect of Bi2S3 that led to the phase transition of the lauric acid on the surface of the composite coating. After 5 min NIR light irradiation, the contact angle decreased from 156° to 60.6°, and the electrochemical tests showed that the superhydrophobic composite coating with wettability-transformable could provide effective protection for Mg alloy substrate. The antibacterial efficiency of the coated Mg alloy reached 99.9% against Staphylococcus aureus and 95.8% against Escherichia coli, respectively. Meanwhile, the superhydrophobic composite coating with wettability-transformable had good biocompatibility with over 81.2% cell viability on MC3T3-E1 cells and good early cell growth and adhesion. This work provides a strategy for preparing wettability-transformable superhydrophobic hydroxyapatite coatings on Mg-based implants with dual-function of antibacterial ability and osteogenic activity.

Photobiomodulation-Based Synergic Effects of Pt-Coated TiO2 Nanotubes and 850 nm Near-Infrared Irradiation on the Osseointegration Enhancement: In Vitro and In Vivo Evaluation.

Photobiomodulation (PBM) therapy is known to have the potential to improve bone regeneration after implant surgery. However, the combinatory effect of the nanotextured implant and PBM therapy on osseointegration has not yet been proved. This study evaluated the photobiomodulation-based synergistic effects of Pt-coated titania nanotubes (Pt-TiO2 NT) and 850 nm near-infrared (NIR) light on osteogenic performance in vitro and in vivo. The FE-SEM and the diffuse UV-Vis-NIR spectrophotometer were used to perform the surface characterization. The live-dead, MTT, ALP, and AR assays were tested to perform in vitro tests. The removal torque testing, the 3D-micro CT, and the histological analysis were used to conduct in vivo tests. The live-dead and MTT assay resulted in Pt-TiO2 NTs being biocompatible. The ALP activity and AR assays demonstrated that the combination of Pt-TiO2 NT and NIR irradiation significantly enhanced osteogenic functionality (p < 0.05). The results of in vivo test, employing the removal torque testing, the 3D-micro CT, and histological analysis, showed overall improved outcomes; however, no significant difference was observed between the control and experimental groups (p > 0.05). Therefore, we confirmed the possibility of the combination of Pt-TiO2 NT and NIR light as a promising technology for implant surgery in dentistry.

Using host-guest interactions at the interface of quantum dots to load drug molecules for biocompatible, safe, and effective chemo-photodynamic therapy against cancer.

Combining photodynamic therapy (PDT) and chemotherapy (CHT) by loading an anti-cancer drug and a photosensitizer (PS) into the same delivery nanosystem has been proposed as an effective approach to achieve synergistic effects for a safe cancer treatment. However, exploring an ideal delivery nanosystem has been challenging, because the noncovalent interactions must be maintained between the multiple components to produce a stable yet responsive nanostructure that takes into account the encapsulation of drug molecules. We addressed this issue by engineering the interfacial interaction between Ag2S quantum dots (QDs) using a pillararene derivative to direct the co-self-assembly of the entire system. The high surface area-to-volume ratio of the Ag2S QDs provided ample hydrophobic space to accommodate the anti-drug molecule doxrubicine. Moreover, Ag2S QDs served as PSs triggered by 808 nm near-infrared (NIR) light and also as carriers for high-efficiency delivery of drug molecules to the tumor site. Drug release experiments showed smart drug release under the acidic microenvironments (pH 5.5) in tumor cells. Additionally, the Ag2S QDs demonstrated outstanding PDT ability under NIR light, as confirmed by extracellular and intracellular reactive oxygen species generation. Significant treatment efficacy of the chemo-photodynamic synergistic therapy for cancer using the co-delivery system was demonstrated via in vitro and in vivo studies. These findings suggest that our system offers intelligent control of CHT and PDT, which will provide a promising strategy for constructing hybrid systems with synergistic effects for advanced applications in biomedicine, catalysis, and optoelectronics.

S-Cu-FC/CuS modified GO carboxymethyl cellulose hydrogel for enhanced photocatalytic sterilization through homo-heterojunction interface accelerated charge transfer.

Charge transfer and separation play a critical role in the photocatalytic efficiency of photoresponsive materials and their subsequent applications. Herein, for the first time, we constructed a homo-heterostructured S-Cu-FC/CuS modified carboxymethyl cellulose (CMC) hydrogel doped with graphene oxide (GO) (S-Cu-FC/CuS/GO@CMC) through an in situ ionic complexation reaction, which exhibited enhanced photocatalytic performance under 808 nm near-infrared (NIR) light irradiation. On the one hand, photo-excited charges can rapidly transfer across the homo-heterojunction interface with copper atoms in S-Cu-FC/CuS as both donors and acceptors. On the other hand, the interface between GO and S-Cu-FC/CuS also favors the fast transfer of photogenerated charges. Hence, with the assistance of a photothermal effect, the enhanced photocatalytic performance of S-Cu-FC/CuS/GO endowed the hydrogel with robust sterilization ability for killing 99.5% S. aureus and 100.0% E. coli under 10 min NIR light irradiation. An in vivo test disclosed that this hydrogel could also accelerate the healing of bacteria-infected wounds.

Liposome‐Mediated Biomimetic Delivery of PLK3 Inhibitor with NIR II‐Triggered Release Prevents Renal Ischemia‐Reperfusion Injury

AbstractAs one of the leading causes of acute kidney injury (AKI), ischemia‐reperfusion injury (IRI) results in tubular necrosis and renal inflammation. Here, from gene screening, it is found that Polo‐like kinase 3 (PLK3), but not other PLKs, is highly up‐regulated during mouse IRI. In vivo administration of PLK3 inhibitor alleviates IRI‐induced AKI, but induces myelosuppression. Thus, a novel liposome‐mediated biomimetic delivery system with 1080 nm near infrared (NIR)‐triggered release to specifically and efficiently delivering the inhibitor to the kidney is developed. NIR light irradiation to kidney results in an excellent effect for reduced immune cell infiltration and renal inflammation. Mechanistically, PLK3 inhibition suppresses the degradation of hypoxia‐inducible factor‐1α (HIF‐1α) and reactive oxygen species (ROS)‐mediated oxidative stress, thus protecting the renal tubular epithelial cells from cell death and preventing macrophage activation and renal inflammation. Thus, the NIR light‐triggered liposome system provides an efficient candidate treatment for AKI without systemic side effect.

Gold-based nanoparticles realize photothermal and photodynamic synergistic treatment of liver cancer and improve the anaerobic tumor microenvironment under near-infrared light.

In order to solve the different pains caused by traditional cancer treatment methods such as surgical treatment, the nano-drug delivery system provides new ideas for cancer treatment. In this paper, a novel anti-tumor therapy nanoparticle, P(AAm-co-AN)-AuNRs@CeO2-Ce6(PA/Ce6), is prepared, which provides a novel idea for liver cancer treatment. The CeO2-coated gold nanorods were grafted onto the surface of the temperature-sensitive polymer P(AAm-co-AN)-CTPD. The photosensitizer Ce6 is loaded on the surface of the nanoparticles and the polymer layer. CeO2 can effectively alleviate the tumor anaerobic microenvironment, and under 808 nm near-infrared (NIR) excitation, the gold nanorods achieve photothermal conversion to induce local heating, which leads to the phase transition of the polymer layer and realizes a controllable release mechanism. In addition, 660 nm NIR light can effectively induce Ce6 to produce singlet oxygen, thereby effectively killing cancer cells. Under the 808 nm laser irradiation within 600 s, the PA/Ce6 solution can heat up to about 60°C, which was enough to ablate both cancer cells and tumor tissues. When the temperature was 50°C, the cumulative release rate of Ce6 was 95.31%. Under the 808 nm laser irradiation, oxygen production capacity of PA/Ce6 was higher and can effectively reduce the content of hydrogen peroxide in cancer cells. Compared to free Ce6, the reactive oxygen species-mediated fluorescence of PA/Ce6 nanoparticles was greater. The cell viability and migration of HepG2 cells were decreased after the 660 and 880 nm lasers were irradiated at the same time. The cancer cells were further inhibited, showing a good in vitro anti-tumor effect. PA-DOX showed the best tumor growth inhibitory effect under NIR laser irradiation and had no acute toxicity in vivo. Due to the existence of AuNRs, nanoparticles had high-efficiency photothermal conversion ability to achieve photothermal therapy. Ce6 can generate singlet oxygen under the excitation of 660 nm laser to realize photodynamic therapy. The experimental results also showed that PA/Ce6 can effectively decompose hydrogen peroxide under laser irradiation, aiming to effectively alleviate the anaerobic microenvironment of tumors. These indicate that PA/Ce6 plays a promising role for hepatocellular carcinoma treatment.

Rational Design of Multifunctional CuS Nanoparticle‐PEG Composite Soft Hydrogel‐Coated 3D Hard Polycaprolactone Scaffolds for Efficient Bone Regeneration

Abstract3D‐printed polycaprolactone (PCL) scaffolds have been extensively studied for application in bone tissue engineering. However, PCL‐based scaffolds with enhanced bioactivity and intelligent delivery capability for bone repair remains challenging. Herein, CuS nanoparticle‐PEG soft hydrogel‐coated 3D hard polycaprolactone scaffolds (denoted as CuS‐PEG‐PCL scaffold) are rationally designed for efficient bone regeneration. CuS nanoparticles cross‐linked PEG hydrogel (CuS‐PEG‐hydrogel) endows the PCL‐based scaffold with excellent photothermal properties and stable soft elasticity, while the PCL scaffold provides excellent mechanical performance. Upon exposure to 1064 nm near‐infrared (NIR) light irradiation, dexamethasone sodium phosphate (Dexp), stored in the CuS‐PEG‐PCL scaffold, can be controllably released, which efficiently promotes osteogenic differentiation of bone mesenchymal stem cells (BMSCs). In addition, the combination of mild heating at 42 ± 0.5 °C further promoted osteogenic differentiation of BMSCs. Subsequently, this Dexp‐loaded CuS‐PEG‐PCL scaffold (D‐CuS‐PEG‐PCL scaffold) with NIR light treatment at the tibial defect of rats presented the highest bone regeneration capacity. These findings demonstrate that the Dexp‐loaded CuS‐PEG‐hydrogel can effectively modify the 3D printed PCL scaffold. Therefore, this multifunctional scaffold with a soft‐hard hybrid structure has the potential to become an advanced drug delivery vehicle in the treatment of large bone defects.

NIR-activated multi-hit therapeutic Ag2S quantum dot-based hydrogel for healing of bacteria-infected wounds

Hydrogel dressings are highly biocompatible and can maintain a moist wound environment, suggesting constructing an efficient multi-modal antibacterial hydrogel platform is a promising strategy for treating bacterial wound infections. In this work, a composite Ag2S quantum dot/mSiO2 NPs hydrogel (NP hydrogel) with antibacterial ability was constructed by incorporating Ag2S quantum dots (QDs) modified by mesoporous silica (mSiO2) into the network structure of 3-(trimethoxylmethosilyl) propyl methacrylate based on free radical polymerization. The NP hydrogel showed outstanding controllable photothermal and photodynamic characteristics under 808 nm near infrared (NIR) light irradiation, with a photothermal conversion efficiency of 57.3%. Additionally, the release of Ag+ could be controlled by the inherent volume change of the NP hydrogel made of N-isopropylacrylamide (NIPAAm) and acrylamide (AAm) during NIR laser exposure, with the embedded Ag2S QDs working as a reservoir to release Ag+ continuously from the hydrogel matrix to achieve bactericidal activity. The synergetic effects between hyperthermia, radical oxygen species, and Ag+ released under NIR radiation endowed the NP hydrogel with prominent antibacterial properties against Escherichia coli (E. coli) and methicillin-resistant Staphylococcus aureus (MRSA), with an inhibition rate of 99.7% and 99.8%, respectively. In vivo wound healing experiments indicated that the NP hydrogel could enhance bacterial clearance, increase collagen coverage area and up-regulate VEGF expression, exhibiting high biocompatibility. Overall, this study proposed an efficient and highly biocompatible multi-modal therapeutic nanohydrogel, opening up a new way for developing broad-spectrum antibacterial wound dressings to treat bacterial wound infections. Statement of significanceBacterial wound infection is still one of the most difficult medical problems. In this work, a stimulating NIR-responsive hydrogel encapsulating functional Ag2S QDs was prepared, which showed high photothermal conversion efficiency (57.3%) and outstanding antibacterial ability under 808 nm NIR laser, killing 99.7% and 99.8% of E. coli and MRSA in 4 min, respectively. During NIR light irradiation, the release rate of Ag+ could be regulated by the intrinsic volume transition of the hydrogel, leading to remarkable antibacterial properties in vitro and in vivo under the combined action of hyperthermia, radical oxygen species and Ag+ released. This study proposed a novel multi-modal therapeutic nanohydrogel, opening up a new way for developing broad-spectrum antibacterial wound dressings to treat bacterial wound infections.

Optically Programmable Plasmon Enhanced Fluorescence-Catalytic Hairpin Assembly Signal Amplification Strategy for Spatiotemporally Precise Imaging.

Signal amplification strategies with spatiotemporally high sensitivity can provide more accurate information and hold great promise for improving the accuracy of disease diagnosis. Herein, a 808 nm near-infrared (NIR) light-activated plasmon enhanced fluorescence-catalytic hairpin assembly (PEF-CHA) signal amplification strategy was proposed for spatiotemporally controllable precise imaging of miRNA in vitro and in vivo with ultrasensitivity. The proposed 808 nm NIR light-activated PEF-CHA signal amplification strategy is constructed through combining up-conversion photocontrol and PEF technologies with CHA. It is worth noting that the laser irradiation-induced overheating effect could be effectively alleviated by using Nd3+-sensitized upconversion nanoparticles (UCNPs) to convert 808 nm NIR light to ultraviolet (UV) light, which is almost nondestructive to cells or tissues. In addition, nonspecific activation as well as false positive signals can be effectively avoided. Moreover, the detection limit can be reduced by approximate 38 times thanks to the high sensitivity of the proposed strategy. Furthermore, we demonstrate that the 808 nm NIR light-activated PEF-CHA signal amplification strategy can be expanded to sensitive and activatable imaging of intratumoral miRNAs in living mice, showing feasible prospects for precise biological and medical analysis.

Kinetics-Controlled Super-Assembly of Asymmetric Porous and Hollow Carbon Nanoparticles as Light-Sensitive Smart Nanovehicles.

The rational design and controllable synthesis of hollow nanoparticles with both a mesoporous shell and an asymmetric architecture are crucially desired yet still significant challenges. In this work, a kinetics-controlled interfacial super-assembly strategy is developed, which is capable of preparing asymmetric porous and hollow carbon (APHC) nanoparticles through the precise regulation of polymerization and assembly rates of two kinds of precursors. In this method, Janus resin and silica hybrid (RSH) nanoparticles are first fabricated through the kinetics-controlled competitive nucleation and assembly of two precursors. Specifically, silica nanoparticles are initially formed, and the resin nanoparticles are subsequently formed on one side of the silica nanoparticles, followed by the co-assembly of silica and resin on the other side of the silica nanoparticles. The APHC nanoparticles are finally obtained via high-temperature carbonization of RSH nanoparticles and elimination of silica. The erratic asymmetrical, hierarchical porous and hollow structure and excellent photothermal performance under 980 nm near-infrared (NIR) light endow the APHC nanoparticles with the ability to serve as fuel-free nanomotors with NIR-light-driven propulsion. Upon illumination by NIR light, the photothermal effect of the APHC shell causes both self-thermophoresis and jet driving forces, which propel the APHC nanomotor. Furthermore, with the assistance of phase change materials, such APHC nanoparticles can be employed as smart vehicles that can achieve on-demand release of drugs with a 980 nm NIR laser. As a proof of concept, we apply this APHC-based therapeutic system in cancer treatment, which shows improved anticancer performance due to the synergy of photothermal therapy and chemotherapy. In brief, this kinetics-controlled approach may put forward new insight into the design and synthesis of functional materials with unique structures, properties, and applications by adjusting the assembly rates of multiple precursors in a reaction system.

Shape effects of gold nanoparticles in photothermal cancer therapy

Gold Nanoparticles based Plasmonic Photothermal Therapy (PPTT) has recently been extensively studied in cancer treatment, based on the local hyperthermia induced by their plasmonic photothermal effect on cancer cells or tissues. Although AuNPs with various morphologies have shown photothermal conversion capabilities, their performance in photothermal therapy is still in debate. To reveal the AuNPs with the most promising PPTT performance, three commonly established gold nanostructures: gold nanospheres (AuNSs), gold nanorods (AuNRs), gold nanostars (AuNSTs), were synthesized in this study with identical mPEG-SH surface modification. The corresponding PTT performance and antitumor effect were evaluated and compared. It was found that all AuNPs can convert 808 nm Near-Infrared (NIR) laser light energy into heat through the Localized Surface Plasmon Resonance effect, and AuNSTs showed the highest photothermal conversion efficiency. In vitro cell experiments demonstrated that all PEGylated AuNPs had low cytotoxicity and AuNSTs were the most capable ones in inducing local hyperthermia under an identical condition of 10 min 300 mW/cm2 NIR light irradiation. Therefore, with the same surface modification, AuNSTs should be the most promising agent for PTT therapy among their counterparts.

Using Gd-Enhanced β-NaYF4:Yb,Er Fluorescent Nanorods Coupled to Reduced TiO2 for the NIR-Triggered Photocatalytic Inactivation of Escherichia coli

β-NaYF4:Yb,Er,Gd fluorescent nanorods were successfully coupled to a reduced TiO2 (UCNPs@R-TiO2) nanocomposite and applied to visible-light catalytic sterilization under 980 nm near-infrared (NIR) light illumination. The UCNPs (β-NaYF4:Yb,Er,Gd) absorb the NIR light and emit red and green light. The visible light can be absorbed by the R-TiO2 (Eg = 2.8 eV) for the photocatalytic reaction. About 98.1% of Escherichia coli were effectively killed upon 12 min of NIR light irradiation at a minimum inhibitory concentration (MIC) of 40 μg/mL UCNPs@R-TiO2 nanocomposite. The bactericidal properties were further evaluated by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) analysis. We found that the high bactericidal activity was due to the synergistic effect between the UCNPs and R-TiO2. Moreover, the UCNPs show excellent upconversion luminance properties, and the introduction of visible-light-absorbed R-TiO2 nanoparticles (2.8 eV) was conducive to the efficient separation and utilization of photogenerated electron-hole pairs.

Ball-milling fabrication of BiAgOS nanoparticles for 808 nm light mediated photodynamic/photothermal treatment

Photodynamic therapy (PDT) and photothermal therapy (PTT) combined treatment guided by imaging diagnosis has brought the cancer treatment into a new stage. But simple nanoplatforms with multifunctional therapeutic performance are rarely designed. Herein, we adopt ball-milling method to fabricate spherical BiAgOS nanoparticles as photosensitizer to apply for 808 nm near-infrared (NIR) light triggered PDT and PTT co-therapy. The polyethylene glycol (PEG) modified BiAgOS NPs show a great absorption in the range of visible light to near-infrared region. Under 808 nm laser irradiation, BiAgOS-PEG NPs have obvious photothermal and photosensitive effects together with excellent X-ray computed tomography (CT) imaging function. The in vitro and in vivo experiments exhibit that the BiAgOS-PEG NPs have good biocompatibility, excellent tumor cells inhibition effects simultaneously. Our finding described the first use of BiAgOS-PEG NPs as a semiconductor photosensitizer for anti-cancer treatment, providing a promising strategy to fabricate this kind of material for imaging guided NIR light induced combined tumor treatment.

Bright Blue, Green, and Red Luminescence from Dye-Sensitized Core@Shell Upconversion Nanophosphors under 800 nm Near-Infrared Light.

In this study, Li-based blue- and green-emitting core@shell (C@S) upconversion nanophosphors (UCNPs) and NaGdF4-based red-emitting C@S UCNPs were synthesized, and IR-808 dyes were conjugated with the C@S UCNPs to enhance upconversion (UC) luminescence. The surface of the as-synthesized C@S UCNPs, which was originally capped with oleic acid, was modified with BF4− to conjugate the IR-808 dye having a carboxyl functional group to the surface of the UCNPs. After the conjugation with IR-808 dyes, absorbance of the UCNPs was significantly increased. As a result, dye-sensitized blue (B)-, green (G)-, and red (R)-emitting UCNPs exhibited 87-fold, 10.8-fold, and 110-fold enhanced UC luminescence compared with B-, G-, and R-emitting Nd3+-doped C@S UCNPs under 800 nm near-infrared (NIR) light excitation, respectively. Consequently, dye-sensitized UCNPs exhibiting strong UC luminescence under 800 nm NIR light excitation have high applicability in a variety of biological applications.

Rapid bacteria trapping and killing of metal-organic frameworks strengthened photo-responsive hydrogel for rapid tissue repair of bacterial infected wounds

During the wound healing process, it is necessary to protect the tissue from bacterial infections and other external damage in environment. Functional artificial hydrogels as suitable wound dressings to act as barriers have attracted more and more attention. In the study described herein, quaternary ammonium and double-bond modified chitosan and metal–organic framework (MOF) particles (Prussian blue nanoparticles [PBNPs]) were used to synthesize photosensitive hydrogels through free radical polymerization. The synthesized hydrogels exhibited excellent photothermal properties under 808 nm near-infrared (NIR) light irradiation due to the existence of PBNPs, which could absorb NIR light and produce light due to the charge transfer between Fe3+ and Fe2+ in the structure. The hydrogels can capture the bacteria tightly by electrostatic absorption. During this course, the normal metabolism of bacteria was inhibited due to the perturbation of the surface potential of the bacterial membrane and the subsequent inhibition of bacterial respiration, which led to the highly effective, rapid killing of bacteria together with the synergistic action of photothermal effects. The antibacterial ratio of the hydrogels could reach up to 99.97% and 99.93% against Staphylococcus aureus and Escherichia coli, respectively. Furthermore, PBNPs particles were also able to strengthen the mechanical property of the hydrogel through the interfacial interaction between the chitosan polymer and the PBNPs. The synthesized hydrogels also showed good in vitro biocompatibility and excellent in vivo antibacterial properties with no damage to the major organs. Thus, the synthesized hydrogels have great potential as a safe and efficient wound dressing.

Photobiomodulation Mediates Neuroprotection against Blue Light Induced Retinal Photoreceptor Degeneration.

Potent neuroprotective effects of photobiomodulation with 670 nm red light (RL) have been demonstrated in several models of retinal disease. RL improves mitochondrial metabolism, reduces retinal inflammation and oxidative cell stress, showing its ability to enhance visual function. However, the current knowledge is limited to the main hypothesis that the respiratory chain complex IV, cytochrome c oxidase, serves as the primary target of RL. Here, we demonstrate a comprehensive cellular, molecular, and functional characterization of neuroprotective effects of 670 nm RL and 810 nm near-infrared light (NIRL) on blue light damaged murine primary photoreceptors. We show that respiratory chain complexes I and II are additional PBM targets, besides complex IV, leading to enhanced mitochondrial energy metabolism. Accordingly, our study identified mitochondria related RL- and NIRL-triggered defense mechanisms promoting photoreceptor neuroprotection. The observed improvement of mitochondrial and extramitochondrial respiration in both inner and outer segments is linked with reduced oxidative stress including its cellular consequences and reduced mitochondria-induced apoptosis. Analysis of regulatory mechanisms using gene expression analysis identified upregulation α-crystallins that indicate enhanced production of proteins with protective functions that point to the rescued mitochondrial function. The results support the hypothesis that energy metabolism is a major target for retinal light therapy.

Gold Nanoshell-Linear Tetrapyrrole Conjugates for Near Infrared-Activated Dual Photodynamic and Photothermal Therapies.

Photodynamic therapy (PDT) is a treatment in which photoactive compounds delivered to cancerous tissues are excited with light and then transfer the absorbed energy to adjacent tissue oxygen molecules to generate toxic singlet oxygen (1O2). As 1O2 is produced only where light and photosensitizers (PSs) are combined, PDT holds promise as a minimally invasive, highly selective treatment for certain cancers. The practical application of PDT requires easily synthesized, water-soluble PSs that have low dark toxicities, high 1O2 quantum yields, and efficient absorption of 650–850 nm near-infrared (NIR) light, which deeply penetrates tissue. We recently developed a linear tetrapyrrole metal complex, Pd[DMBil1]–PEG750, that meets most of these criteria. This complex is remarkably effective as a PS for PDT against triple-negative breast cancer (TNBC) cells but, critically, it does not absorb NIR light, which is necessary to treat deeper tumors. To enable NIR activation, we synthesized a new derivative, Pd[DMBil1]–PEG5000–SH, which bears a thiol functionality that facilitates conjugation to NIR-absorbing gold nanoshells (NSs). Upon excitation with pulsed 800 nm light, NSs emit two-photon-induced photoluminescence spanning 500–700 nm, which can sensitize the attached PSs to initiate PDT. Additionally, NSs produce heat upon 800 nm irradiation, endowing the NS–PS conjugates with an auxiliary photothermal therapeutic (PTT) capability. Here, we demonstrate that NS–PS conjugates are potent mediators of NIR-activated tandem PDT/PTT against TNBC cells in vitro. We show that Pd[DMBil1]–PEG5000–SH retains the photophysical properties of the parent Pd[DMBil1] complex, and that NS–PS generate 1O2 under pulsed 800 nm irradiation, confirming activation of the PSs by photoluminescence emitted from NSs. TNBC cells readily internalize NS PS conjugates, which generate reactive oxygen species in the cells upon pulsed NIR irradiation to damage DNA and induce apoptosis. Together, these findings demonstrate that exploiting photoluminescent NSs as carriers of efficient Pd[DMBil1] PSs is an effective strategy to enable NIR light-activated tandem PDT/PTT.

Highly bright Li(Gd,Y)F4:Yb,Er upconverting nanocrystals incorporated hole transport layer for efficient perovskite solar cells

We report synthesis of highly bright Li(Gd,Y)F4:Yb,Er upconversion (UC) nanophosphors and integrate them into the hole transport layers (HTLs) to examine their optical and electrical effects in perovskite solar cells (PSCs). Mono-disperse, single tetragonal-phase Li(Gd,Y)F4:Yb,Er upconversion nanocrystals (UCNCs) were prepared by a thermal decomposition method. The grown Li(Gd,Y)F4:Yb,Er UCNCs displayed tetragonal bipyramidal morphologies and intense UC green luminescence. The octahedral UCNCs were blended into the Spiro-OMeTAD-based HTL with different weight ratios. At an optimal weight ratio of UCNCs, the PSCs based on the upconverting transport hole layer achieved an average power conversion efficiency of 18.34% under AM1.5G illumination, an increase over 25% compared with conventional HTL based PSCs (14.69%). We systematically explore the optical and electrical enhancement effects of Li(Gd,Y)F4:Yb,Er UCNCs via UV–visible absorption, diffused reflectance, external quantum efficiency (EQE), steady-state and time-resolved photoluminescence, photocurrent property and the space-charge-limited-current (SCLC) measurements. It was found that with the addition of the octahedral UCNCs in a proper proportion the composite HTL exhibits high charge carrier mobility and charge carrier transfer/collection capability. Besides, the embedded UCNCs boost the light harvesting of the PSCs over a large range of wavelengths from 400 nm to 800 nm. Furthermore, with a 980 nm near-infrared (NIR) laser irradiation, the embedded UCNCs acted as efficient upconverting centers to up-convert the NIR light for promisingly expanding the effective absorption spectrum for PSCs.