Near-infrared light-induced homogeneous photoelectrochemical biosensor based on 3D walking nanomotor-assisted CRISPR/Cas12a for ultrasensitive microRNA-155 detection

The dysregulation of microRNA (miRNA) expression levels is intricately linked to a myriad of human diseases, and the precise and delicate detection thereof holds paramount significance in the realm of clinical diagnosis and therapy. Herein, a near-infrared (NIR) light-mediated homogeneous photoelectrochemical (PEC) biosensor was constructed for miRNA-155 detection based on NaYF4: Yb, Tm@ZnIn2S4 (NYF@ ZIS) coupled with a three-dimensional (3D) walking nanomotor-assisted CRISPR/Cas12a strategy. The upconverted light emitted by the NYF in the visible and UV region upon NIR light excitation could be utilized to excite ZIS to produce a photocurrent response. The presence of target miRNA-155 initiated an amplification reaction within the 3D walking nanomotor, resulting in the production of multiple nucleic acid fragments. These fragments could activate the collateral cleavage capability of CRISPR/Cas12a, leading to the indiscriminate cleavage of single-stranded DNA (ssDNA) on ALP-ssDNA-modified magnetic beads and the subsequent liberation of alkaline phosphatase (ALP). The released ALP facilitated the catalysis of ascorbic acid 2-phosphate to generate ascorbic acid as the electron donor to capture the photogenerated holes on the NYF@ZIS surface, resulting in a positively correlated alteration in the photocurrent response. Under optimal conditions, the NIR light-initiated homogeneous PEC biosensor had the merits of good linear range (0.1 fM to 100 pM), an acceptable limit of detection (65.77 aM) for miRNA-155 detection. Considering the pronounced sensitivity, light stability, and low photodamage, this strategy presents a promising platform for detecting various other miRNA biomarkers in molecular diagnostic practice.

Significantly enhanced uranium extraction by intelligent light-driven nanorobot catchers with precise controllable moving trajectory

Uranium, as the most essential resource for nuclear power production, provides 13% of global electricity demand, has attracted considerable attention. However, it is still a great challenge for uranium extraction from natural water like salt lakes as the background of high salinity and low concentration (3.3 ∼ 330 ppb). Meanwhile, current uranium extraction strategies are generally focus on extraction capacity or selectivity but neglect to enhance extraction rate. In this work, we designed a novel kind of NIR-driven intelligent nanorobots catchers (MSSA-AO) with amidoxime as claws for uranium capture, which showed almost 100% extraction rate and an ultrafast extraction rate. Importantly, high extraction capacity (221.5 mg g-1) and selectivity were taken into consideration as well as good regeneration performance. Furthermore, amidoxime NRCs boosted in extraction amount about 16.7% during the first 5 min with self-driving performance. Overall, this work suggests a new strategy for ultrafast extraction of uranium from natural water with low abundance selectively by self-propelled NRCs, showing great possibility in outdoor application and promising for meeting huge energy needs globally.

NIR light-facilitated bone tissue engineering

In the last decades, near-infrared (NIR) light has attracted considerable attention due to its unique properties and numerous potential applications in bioimaging and disease treatment. Bone tissue engineering for bone regeneration with the help of biomaterials is currently an effective means of treating bone defects. As a controlled light source with deeper tissue penetration, NIR light can provide real-time feedback of key information on bone regeneration in vivo utilizing fluorescence imaging and be used for bone disease treatment. This review provides a comprehensive overview of NIR light-facilitated bone tissue engineering, from the introduction of NIR probes as well as NIR light-responsive materials, and the visualization of bone regeneration to the treatment of bone-related diseases. Furthermore, the existing challenges and future development directions of NIR light-based bone tissue engineering are also discussed. This article is categorized under: Diagnostic Tools > In Vivo Nanodiagnostics and Imaging Implantable Materials and Surgical Technologies > Nanotechnology in Tissue Repair and Replacement.

Integrating Hybrid Perovskite Nanocrystals into Metal-Organic Framework as Efficient S-Scheme Heterojunction Photocatalyst for Synergistically Boosting Controlled Radical Photopolymerization under 980 nm NIR Light

S-scheme heterojunction photocatalyst MAPbI3@PCN-222 with light absorption extending to the NIR region is constructed by embedding organic-inorganic hybrid perovskite (MAPbI3) into porphyrinic Zr-MOF (PCN-222). Both in situ X-ray photoelectron spectroscopy, ultraviolet photoelectron spectral characterization, and photocatalytic polymerization experiment prove the formation of S-scheme heterojunction. MAPbI3@PCN-222 with a low dosage (90 ppm) displays an impressive photocatalytic ability for 980 nm light-mediated photoinduced electron/energy-transfer-reversible addition-fragmentation chain-transfer (PET-RAFT) polymerization in air. The well-defined controllable-molecular weight polymers including block copolymers and ultrahigh-molecular weight polymers can be achieved with narrow distributions (Mw/Mn < 1.20) via rapid photopolymerization. The industrial application potential of the photocatalyst also has been proved by scale-up synthesis of polymers with low polydispersity under NIR light-induced photopolymerization in a large-volume reaction system (200 mL) with high monomer conversion up to 99%. The penetration photopolymerization through the 5 mm polytetrafluoroethylene plate and excellent photocontrollable behavior illustrate the existence of long-term photogenerated electron transfer of heterojunction and abundant free radicals in photopolymerization. The photocatalyst still retains high catalytic activity after 10 cycles of photopolymerization in air. It is revealed for the first time that the special PET-RAFT polymerization pathway is initiated by the aldehyde-bearing α-aminoalkyl radical derived from the oxidization of triethanolamine (TEOA) by the heterojunction photocatalyst. This research offers a new insight into understanding the NIR-light-activated PET-RAFT polymerization mechanism in the presence of TEOA.

Recent Advances in NIR or X-ray Excited Persistent Luminescent Materials for Deep Bioimaging

Due to their persistent luminescence, persistent luminescent (PersL) materials have attracted great interest. In the biomedical field, the use of persistent luminescent nanoparticles (PLNPs) eliminates the need for continuous in situ excitation, thereby avoiding interference from tissue autofluorescence and significantly improving the signal-to-noise ratio (SNR). Although persistent luminescence materials can emit light continuously, the luminescence intensity of small-sized nanoparticles in vivo decays quickly. Early persistent luminescent nanoparticles were mostly excited by ultraviolet (UV) or visible light and were administered for imaging purposes through ex vivo charging followed by injection into the body. Limited by the low in vivo penetration depth, UV light cannot secondary charge PLNPs that have decayed in vivo, and visible light does not penetrate deep enough to reach deep tissues, which greatly limits the imaging time of persistent luminescent materials. In order to address this issue, the development of PLNPs that can be activated by light sources with superior tissue penetration capabilities is essential. Near-infrared (NIR) light and X-rays are widely recognized as ideal excitation sources, making persistent luminescent materials stimulated by these two sources a prominent area of research in recent years. This review describes NIR and X-ray excitable persistent luminescence materials and their recent advances in bioimaging.

Second-Generation Soft Actuators Driven by NIR Light Based on Croconaine Dye-Doped Vitrimers

Soft actuators with photo-response can be selectively driven by the light source, but it is challenging to achieve a selective response of multiple components under a uniform light field, which is actually of great importance for the development of soft robots. In this work, a series of near-infrared light (NIR)-responsive vitrimers (CR-vitrimers) are synthesized by carboxylate transesterification using carboxyl-bearing croconaine dye (CR-800) as a photothermal agent (PTA). NIR-responsive liquid crystalline elastomers (CR-vitrimer-LCEs) under NIR laser (λmax = 808 nm) without the template can be further prepared. More importantly, the dynamic covalent bonding properties of vitrimer allow for the fabrication of a hand-shaped actuator by hot pressing, consisting of "fingers" with different NIR-response threshold values. After programming as needed, the hand-shaped actuator successfully achieves local and sequential control under a uniform NIR light field.

Near-Infrared Light-Activated Ruthenium Complex-based Photocage for Cancer Phototherapy

Conventional photocages only respond to short wavelength light, which is a significant obstacle to developing efficient phototherapy in vivo. The development of photocages activated by near-infrared (NIR) light at wavelengths from 700 to 950 nm is important for in vivo studies but remains challenging. Herein, we describe the synthesis of a photocage based on a ruthenium (Ru) complex with NIR light-triggered photocleavage reaction. The commercial anticancer drug, tetrahydrocurcumin (THC), was coordinated to the Ru(II) center to create the Ru-based photocage that is readily responsive to NIR light at 760 nm. The photocage inherited the anticancer properties of THC. As a proof-of-concept, we further engineered a self-assembled photocage-based nanoparticle system with amphiphilic block copolymers. Upon exposure to NIR light at 760 nm, the Ru complex-based photocages were released from the polymeric nanoparticles and efficiently inhibited tumor proliferation in vivo.

Ag-enhanced CeF3-O: highly enhanced photocatalytic performance under NIR light irradiation

CeF₃-O with intermediate band showed improved synergic photodegradation activity toward HCl-TC and RhB under NIR light irradiation when enhanced by Ag as a cocatalyst. Ag⁺ ions take electrons from the second transition in CeF₃-O's intermediate band, which are then reduced to Ag as cocatalyst. The photodegradation efficiencies of HCl-TC by various Ag/CeF₃-O nanoparticles in 180-min increase from 26.5 to 73.1%. The optimal Ag/CeF₃-O-100 is about 2.76 times that of pure CeF₃-O. Ag/CeF₃-O-100 has an apparent rate constant of 4.5 × 10^-3 min^-1, which is 3.0 times that of pure CeF₃-O. Similarly, Ag/CeF₃-O-10 achieves a superior photodegradation efficiency of RhB at 96.7% under NIR light within 120 min. Its apparent rate constant of 27.7 × 10^-3 min^-1 is 12.0 times that of pure CeF₃-O (2.3 × 10^-3 min^-1). Further, the turnover frequencies of Ag/CeF₃-O nanoparticles are greatly higher than that of the corresponding pure CeF₃-O nanoparticles. Ag-enhanced CeF₃-O has a unique metal-semiconductor interface where Ag acts as a bridge for facilitating charge transfer and the separation efficiency of photogenerated carries. The synergic effect between CeF₃-O and Ag provides a practical technique for enhancing the wastewater treatment with NIR light irradiation.

Quantum Dot-Based Micromotors with NIR-I Light Photocatalytic Propulsion and NIR-II Fluorescence

Here, we report the first PbS quantum dot (QD)-based micromotors with NIR-I light-driven photocatalytic propulsion and NIR-II fluorescence. Under the irradiation of NIR-I light (808 nm), PbS QD-doped cuprous oxide (Cu₂O@PbS) micromotors can display efficient propulsion in a variety of biocompatible fuels such as malic acid, glucose, and urea. Among them, the Cu₂O@PbS micromotors exhibit the best propulsion performance in a very low concentration of malic acid, with an average speed as high as 11.86 μm/s. The enhanced NIR-I photocatalytic activity of Cu₂O@PbS micromotors benefits from the doping of NIR-I PbS QDs that can be excited by NIR-I light and exhibit high electron transport efficiency. The doped PbS QDs can effectively increase the absorption efficiency of the micromotors in the NIR-I region while also inhibiting the recombination of photogenerated electron-hole pairs. Interestingly, due to the presence of NIR PbS QDs, the Cu₂O@PbS micromotors demonstrate prominent and stable NIR-II fluorescence (emission wavelength: 1100 nm), which offer promising potential for visualization of their position in vivo. In comparison to other photocatalytic micromotors, the simple fabrication strategy, excellent NIR-II fluorescence, together with the NIR-I light-dependent propulsion behavior of the current Cu₂O@PbS micromotors, thus pave the way for further development of advanced smart "robots" for intelligent biomedical applications.

Efficient photothermal-assisted photocatalytic hydrogen production over a plasmonic CuNi bimetal cocatalyst

It is challenging to maximize the utilization of solar energy using photocatalysis or photothermal catalysis alone. Herein, we report a full spectrum solar energy driven photothermal-assisted photocatalytic hydrogen production over CuNi bimetallic nanoparticles co-loaded with graphitized carbon nitride nanosheet layers (Cu_xNi_y/CN) which are prepared by a facile in-situ reduction method. Cu₅Ni₅/CN shows a high hydrogen production rate of 267.8 μmol g^-1 h^-1 at room temperature, which is 70.5 and 1.34 times of that for pure CN (3.8 μmol g^-1 h^-1) and 0.5 wt% Pt/CN (216 μmol g^-1 h^-1), respectively. The photothermal catalytic hydrogen activity can be further increased by 3.7 times when reaction solution is external heated to 100 °C. For the photothermal catalytic system, the local surface plasmon resonance (LSPR) effect over active Cu nanoparticles can absorb near-infrared light to generate hot electrons, which are partially quenched to generate heat for heating of the reaction system and partially transported to the active sites, where the Ni nanoparticles as another functional component couple the electrons and heat to finally promote the photothermal catalytic activity. Our result suggests that a rational design of the catalyst with bifunctional atomic components can photothermocatalysis-assisted photocatalysis to maximize utilization solar energy for efficient full spectrum conversion.

Modulation of Local Cellular Activities using a Photothermal Dye-Based Subcellular-Sized Heat Spot

Thermal engineering at the microscale, such as the regulation and precise evaluation of the temperature within cellular environments, is a major challenge for basic biological research and biomaterials development. We engineered a polymeric nanoparticle having a fluorescent temperature sensory dye and a photothermal dye embedded in the polymer matrix, named nanoheater-thermometer (nanoHT). When nanoHT is illuminated with a near-infrared laser at 808 nm, a subcellular-sized heat spot is generated in a live cell. Fluorescence thermometry allows the temperature increment to be read out concurrently at individual heat spots. Within a few seconds of an increase in temperature by approximately 11.4 °C from the base temperature (37 °C), we observed the death of HeLa cells. The cell death was observed to be triggered from the exact local heat spot at the subcellular level under the fluorescence microscope. Furthermore, we demonstrate the application of nanoHT for the induction of muscle contraction in C2C12 myotubes by heat release. We successfully showed heat-induced contraction to occur in a limited area of a single myotube based on the alteration of protein-protein interactions related to the contraction event. These results demonstrate that even a single heat spot provided by a photothermal material can be extremely effective in altering cellular functions.

RAFT Polymerization of Semifluorinated Monomers Mediated by a NIR Fluorinated Photocatalyst

Near-infrared (NIR) light plays an increasingly important role in the field of photoinduced electron/energy transfer-reversible addition-fragmentation chain transfer (PET-RAFT) polymerization due to its unique properties. Yet, the NIR photocatalyst with good stability for PET-RAFT polymerization remains promising. Here, a strategy of NIR PET-RAFT polymerization of semifluorinated monomers using fluorophenyl bacteriochlorin as a photocatalyst with strong absorption at the NIR light region (710-780 nm) is reported. In which, the F atoms are used to modify reduced tetraphenylporphyrin structure with enhanced photostability of photocatalyst. Under the irradiation of NIR light (λ_max = 740 nm), the PET-RAFT polymerization of semifluorinated methylacrylic monomers presents living/control characteristics and temporal modulation. By the PET-RAFT polymerization-induced self-assembly (PISA) strategy, stable fluorine-containing micelles are constructed in various solvents. In addition, the fluorinated hydrophobic surface is fabricated via a surface-initiated PET-RAFT (SI-PET-RAFT) polymerization using silicon wafer bearing RAFT agents with tunable surface hydrophobicity. This strategy not only enlightens the application of further modified compounds based on porphyrin structure in photopolymerization, but also shows promising potential for the construction of well-defined functional fluoropolymers.

NIR Light-Triggered Quantitative Pulsed Drug Release

Quantitative drug release is important for improving therapeutic efficiency and avoiding side effects. While using long-term delivery system for repeated therapies, it is indispensable but challenging to accurately control the drug dosing. Here, a photocleavable prodrug loaded hydrogel is proposed for near infrared (NIR) light-triggered quantitative pulsed drug release. IR783, a commercially available NIR fluorescent dye, is conjugated with methyl honokiol (mHNK) to give a photocleavable IR783-mHNK prodrug. Injectable glycol chitosan (GC) hydrogel is chosen as a reservoir, in which IR783-mHNK can be efficiently loaded via electrostatic and hydrophobic interactions. Upon 680 nm light-emitting diode (LED) light irradiation, IR783-mHNK cleaves and mHNK is released. Notably, it is found that IR783-mHNK presents synchronous photocleavage-fluorescence bleaching phenomenon. The released amount of mHNK is visible by measuring the residual fluorescent intensity of hydrogel. Quantitative drug release is achieved by controlling irradiation duration and the drug release process is visible by fluorescence imaging. The prodrug-loaded hydrogel shows good stability, minimum leakage and efficient light responsibility both in vitro and in vivo. After light triggering, monitorable quantitative mHNK release and on-demand sleep-promotiing effect are verified in mice without toxicities.

Photobiomodulation at 830 nm Stimulates Migration, Survival and Proliferation of Fibroblast Cells

PURPOSE

Photobiomodulation (PBM) promotes diabetic wound healing by favoring cell survival and proliferation. This study aimed to investigate the potential of PBM in stimulating cellular migration, viability, and proliferation using the transforming growth factor-β1 (TGF-β1)/Smad signaling pathway.

METHODS

The study explored the in vitro effects of near infrared (NIR) light on cell viability (survival) and proliferation as well as the presence of TGF-β1, phosphorylated TGF-β receptor type I (pTGF-βR1) and phosphorylated mothers against decapentaplegic-homolog (Smad)-2/3 (p-Smad2/3) in different fibroblast cell models.

RESULTS

Results show a significant increase in cellular migration in wounded models, and increased viability and proliferation in irradiated cells compared to their respective controls. An increase in the presence of TGF-β1 in the culture media, a reduction in pTGF-βR1 and a slight presence of p-Smad2/3 was observed in the cells.

CONCLUSION

These findings show that PBM at 830 nm using a fluence of 5 J/cm² could induce cell viability, migration and proliferation to favor successful healing of diabetic wounds. This study contributes to the growing body of knowledge on the molecular and cellular effect of PBM and showcases the suitability of PBM at 830 nm in managing diabetic wounds.

Direct Near Infrared Light-Activatable Phthalocyanine Catalysts

The high penetration of near-infrared (NIR) light makes it effective for use in selective reactions under light-shielded conditions, such as in sealed reactors and deep tissues. Herein, we report the development of phthalocyanine catalysts directly activated by NIR light to transform small organic molecules. The desired photocatalytic properties were achieved in the phthalocyanines by introducing the appropriate peripheral substituents and central metal. These phthalocyanine photocatalysts promote cross-dehydrogenative-coupling (CDC) under irradiation with 810 nm NIR light. The choice of solvent is important, and a mixture of a reaction-accelerating (pyridine) and -decelerating (methanol) solvents was particularly effective. Moreover, we demonstrate photoreactions under visible-light-shielded conditions through the transmission of NIR light. A combined experimental and computational mechanistic analysis revealed that this NIR reaction does not involve a photoredox-type mechanism with electron transfer, but instead a singlet-oxygen-mediated mechanism with energy transfer.

Near-Infrared-Light-Modulated Lubricating Coating Enabled by Photothermal Microgels

As a micro-/nano-sized hydrogel, polymeric microgel not only has three-dimensional (3D) molecular networks but also displays the small-size effect, which has been widely used in various fields, such as drug nanocarrier, photonic crystal, functional coating, and aqueous lubrication. In this work, a photothermal lubricating coating was prepared using polymeric/inorganic hybrid microgels and its surficial friction was deliberately modulated by the remote irradiation of near-infrared (NIR) light. Specifically, a photothermal hybrid microgel, Fe₃O₄@poly(N-isopropylacrylamide-co-polyacrylic acid) (Fe₃O₄@PNA), was first fabricated and then sprayed onto poly(ethyleneimine) (PEI)-modified substrate to form a lubricating microgel coating. At room temperature, this microgel coating was hydrophilic and achieved good hydration lubrication with relatively low friction. After the introduction of NIR light, the photothermal microgel coating converted light energy into heat energy for increasing its own temperature rapidly. Due to the thermosensitive PNA shell, the wettability of the coating was transformed to hydrophobicity above the lower critical solution temperature (LCST), resulting in a remarkable increase in friction. In other words, the surficial friction of this microgel coating could be reversibly modulated using NIR light. This work expands the application scope of microgels in the field of aqueous lubrication and introduces the functional microgels into making the smart lubricating coating for the first time. This basic research in the field of friction control may provide an efficient strategy for the design of interfacial sensing, controlled transmission, and intelligent manipulator.

Near-infrared light responsive dendrimers facilitate the extraction of bicalutamide from human plasma and urine

BACKGROUND

Today, it is well accepted that the quantitative measurement of anti-cancer drugs in human biological samples requires the development and validation of efficient bioanalytical methods. This study attempts to provide a high-capacity and thermo-sensitive nano-adsorbent for bicalutamide extraction from human biological fluids.

MAIN METHODS AND MAJOR RESULTS

In this study, five generations of thermo-sensitive dendrimers were synthesized onto the surface of WS₂ nano-sheets. After drug-loading process from body fluids, the near-infrared (NIR) light (at 808 nm) was applied and light-to-heat conversion by the WS₂ nano-sheets led to shrinkage in polymer chains, resulting the release of the entrapped drug. Finally, the extracted drug was analyzed via HPLC-UV system (at 270 nm). The final nano-adsorbent was described via FE-SEM, XRD, FT-IR, and TGA techniques. The adsorption isotherm data were well fitted by Langmuier isotherm model (R²  = 0.9978). The mean recoveries for spiking bicalutamide at three different concentrations in plasma and urine samples were 92.12% and 94.54% under the NIR light irradiation.

CONCLUSIONS AND IMPLICATIONS

We have developed a smart strategy to analyze bicalutamide in biological samples using near-infrared light irradiation in a controlled manner. All the results indicate the promising application of the proposed method for the extraction and determination of bicalutamide.

Towards new NIR dyes for free radical photopolymerization processes

The use of cheap and safe near-infrared (NIR) light is still the subject of intense research efforts but remains a huge challenge due to the associated low photon energy (wavelength from 0.78 to 2.5 µm). In this study, a series of 17 NIR dyes mainly based on a well-established cyanine scaffold is proposed. Remarkably, 11 of them were never synthesized before. Markedly, noncharged structures, negatively charged cyanine bearing Na⁺ as counter cation, and positively charged cyanines bearing (B(Ph)₄⁻) or (I⁻) as counter anions were examined as promising NIR light photoinitiating systems. Excellent photoinitiating abilities were found for some reported dyes when used in combination with iodonium salt and amine. Markedly, photothermal effects with a huge heater behavior were also observed for different NIR dye structures. Interestingly, the synthesis of interpenetrating polymer networks (IPNs, e.g., for the polymerization of acrylate/epoxy monomer blends) can also be carried out upon NIR light with the proposed systems.

Graft hyper-branched dendrimer onto WS2 nanosheets modified Poly (N-Vinylcaprolactam) as a thermosensitive nanocarrier for Pioglitazone delivery using near-infrared radiation

In this paper, graft-copolymerization of N-vinylcaprolactam and allylamine onto tungsten disulfide (WS₂) in the presence of AIBN as initiator has been carried out to prepare the WS₂@ (NVCL-co-AAm). Subsequent fifth-generation dendrimer was attached to their surface, and used as a nanocarrier for the pioglitazone (PG) drug delivery. The resulting polymer was characterized by FTIR, XRD, TEM, EDX, and TGA. We loaded PG onto polymer and evaluated the drug loading and release patterns in simulated human blood fluid (pH 7.4) for the treatment of diabetes in vitro. The thermosensitive nanocarrier indicated a maximum of 98 % PG release in the simulated human blood fluid at 50 °C within 6 h, and about 18 % of total PG was released from the nanocarrier within 6 h at 37 °C. Herein, we studied near-infrared (NIR) radiation as an irritant for inducing PG release from nanocarrier. Also, PG releasing was 100 % under NIR laser irradiation within 15 min, which was roughly four times of that without laser irradiation. NIR laser light heated the nanocarrier, causing shrinkage of the polymer, which increased the penetrability of the membrane and resulted in PG release. Following four adsorption isotherm models, the Langmuir model excellently explained the adsorption isotherm.

Lanthanide-Doped Nanoparticles for Near-Infrared Light Activation of Photopolymerization: Fundamentals, Optimization and Applications

Photopolymerization refers to a type of polymerization process in which light is utilized as excitation source to initiate polymerization of monomers and oligomers. Despite great progress, photopolymerization is typically induced by ultraviolet or visible light, which still greatly restrains its applications. Upconversion nanoparticles (UCNPs) represent a class of optical nanomaterials that are able to convert low-energy near-infrared (NIR) light into high-energy ultraviolet (or visible light) emissions. In this context, UCNP-assisted photopolymerization has recently attracted extensive attentions due to its unique advantages. In this account, recent advances in the fundamentals, optimization and emerging applications of UCNP-based photopolymerization are reviewed. Fundamental theories of upconversion luminescence and photopolymerization will be introduced first. Various optimization approaches to improve UCNP-assisted photopolymerization are then summarized, followed by diverse emerging applications. Challenges and future perspectives in this area will be provided as a conclusion.

WN Coupled with Bi Nanoparticles to Enhance the Localized Surface Plasmon Resonance Effect for Photocatalytic Hydrogen Evolution

Conversion of light energy and chemical energy in a wide spectrum region, especially in the near-infrared (NIR) light region, is still a challenge in the field of photocatalysis. In this work, a layered Bi-WN photocatalyst with a heterojunction was prepared by reducing flake-shaped WN and flower-shaped Bi₂O₃ in an ammonia atmosphere. Under the process of NIR light (λ > 700 nm)-driven water splitting, the optimal hydrogen (H₂) generation rates based on the Bi-WN photocatalyst can reach to 7.49 μmol g^-1 h^-1, which is 2.47 times higher than that of WN of 3.03 μmol g^-1 h^-1. The result indicates that the Bi-WN photocatalyst can be effective under NIR light. Through ultraviolet-visible-NIR diffuse reflectance spectrum analysis, it can be seen that the light absorption edge of Bi-WN is obviously redshifted. Combining the results of electrochemical characterizations, we have found that the addition of the Bi metal plays an important role in NIR light-driven water splitting. Under irradiation of NIR light, the electrons on the Bi-WN substrate are stronger due to local surface plasmon resonance, which reduces the possibility of recombination of photogenerated electrons and holes on WN. In addition, after the Bi metal absorbs the photon energy, the electron-hole pairs are separated, and the H₂ production rate increases significantly under the combined action of the charge transfer mechanism and the local electric field enhancement mechanism.

Near-Infrared Photo-controlled Permeability of a Biomimetic Polymersome with Sustained Drug Release and Efficient Tumor Therapy

Synthetic polymersomes have structure similarity to bio-vesicles and could disassemble in response to stimuli for "on-demand" release of encapsulated cargos. Though widely applied as a drug delivery carrier, the burst release mode with structure complete destruction is usually taken for most responsive polymersomes, which would shorten the effective drug reaction time and impair the therapeutic effect. Inspired by the cell organelles' communication mode via regulating membrane permeability for transportation control, we highlight here a biomimetic polymersome with sustained drug release over a specific period of time via near-infrared (NIR) pre-activation. The polymersome is prepared by the self-assembling amphiphilic diblock copolymer P(OEGMA-co-EoS)-b-PNBOC and encapsulates the hypoxia-activated prodrug AQ4N and upconversion nanoparticle (PEG-UCNP) in its hydrophilic centric cavity. Thirty minutes of NIR pre-activation triggers cross-linking of NBOC and converts the permeability of the polymersome with sustained AQ4N release until 24 h after the NIR pre-activation. The photosensitizer EoS is activated and aggravates environmental hypoxic conditions during a sustained drug release period to boost the AQ4N therapeutic effect. The combination of sustained drug release with concurrent hypoxia intensification results in a highly efficient tumor therapeutic effect both intracellularly and in vivo. This biomimetic polymersome will provide an effective and universal tumor therapeutic approach.

A CRISPR-Cas9-Based Near-Infrared Upconversion-Activated DNA Methylation Editing System

DNA methylation is a kind of a crucial epigenetic marker orchestrating gene expression, molecular function, and cellular phenotype. However, manipulating the methylation status of specific genes remains challenging. Here, a clustered regularly interspaced palindromic repeats-Cas9-based near-infrared upconversion-activated DNA methylation editing system (CNAMS) was designed for the optogenetic editing of DNA methylation. The fusion proteins of photosensitive CRY2PHR, the catalytic domain of DNMT3A or TET1, and the fusion proteins for CIBN and catalytically inactive Cas9 (dCas9) were engineered. The CNAMS could control DNA methylation editing in response to blue light, thus allowing methylation editing in a spatiotemporal manner. Furthermore, after combination with upconversion nanoparticles, the spectral sensitivity of DNA methylation editing was extended from the blue light to near-infrared (NIR) light, providing the possibility for remote DNA methylation editing. These results demonstrated a meaningful step forward toward realizing the specific editing of DNA methylation, suggesting the wide utility of our CNAMS for functional studies on epigenetic regulation and potential therapeutic strategies for related diseases.

NIR-Light-Activated Ratiometric Fluorescent Hybrid Micelles for High Spatiotemporally Controlled Biological Imaging and Chemotherapy

Intelligent-responsive imaging-therapy strategy has shown great significance for biomedicine. However, it is still a challenge to construct spatiotemporally controlled imaging-therapy systems triggered by near infrared (NIR) light. In this work, NIR-light-activated ratiometric fluorescent hybrid micelles (RFHM) are prepared via the co-assembly of upconversion nanoparticles (UCNPs), doxorubicin (DOX), and UV-light-responsive amphiphilic block copolymer for the spatiotemporally controlled imaging and chemotherapy. Upon NIR light irradiation, UCNPs can convert NIR light to UV light. The emitted UV light induces the photoreaction of copolymer to further trigger ratiometric fluorescence imaging and degradation of hybrid micelles, resulting in rapid DOX release from hybrid micelles for antitumor therapy. The animal experiments reveal that NIR light can not only remotely regulate the ratiometric fluorescence imaging of RFHM in tumor tissue, but also trigger DOX release from RFHM to inhibit tumor growth. Therefore, this study provides a new strategy to achieve high spatial-temporal-controlled biological imaging and chemotherapy.

A dual mode nanophotonics concept for in situ activation of brain immune cells using a photoswitchable yolk-shell upconversion nanoformulation

Here, we introduce a nanophotonics concept for optically triggered activation of microglia. Specifically, we synthesized a yolk-shell structured mesoporous silica coated core-shell upconverting nanoparticles (UCNP@ysSiO₂). The nanoparticles are loaded with microglia activators-bacterial lipopolysaccharide (LPS) together with indocyanine green (ICG), and then capped with β-cyclodextrin (CD) via selective affinity of this compound to photoswitchable azobenzene (Azo). Upon exposure to NIR light, and subsequent trans- to cis photoisomerization of the Azo group induced by the upconversion light, dissociation of β-CD produces the release of LPS. The released LPS activates microglia through a toll-like receptor 4 mediated pathway, while ICG excited by its absorption of the 800 nm upconversion light, produces local heating, thus synergistically activating microglia through heat shock proteins. We propose that the controlled activation of microglia with deep tissue penetrating NIR triggered drug release, may provide a new strategy for in situ treatment of many brain diseases.

Extraspecific Manifestation of Nanoheater's Position Effect on Distinctive Cellular Photothermal Responses

Subcellular localization of nanoparticles plays critical roles in precision medicine that can facilitate an in-depth understanding of disease etiology and achieve accurate theranostic regulation via responding to the aiding stimuli. The photothermal effect is an extensively employed strategy that converts light into heat stimulation to induce localized disease ablation. Despite diverse manipulations that have been investigated in photothermal nanotheranostics, influences of nanoheaters' subcellular distribution and their molecular mechanism on cellular heat response remain elusive. Herein, we disclose the biological basis of distinguishable thermal effects at subcellular resolution by localizing photothermal upconversion nanoparticles into specific locations of cell compartments. Upon 808 nm light excitation, the lysosomal cellular uptake initialized by poly(ethylenimine)-modified nanoheaters promoted mitochondria apoptosis through the activation of Bid protein, whereas the cell surface nanoheaters anchored via metabolic glycol biosynthesis triggered necrosis by direct perturbation of the membrane structure. Intriguingly, these two different thermolyses revealed similar levels of heat shock protein expression in live cells. This study stipulates insights underlying the different subcellular positions of nanoparticles for the selective thermal response, which provides valuable perspectives on optimal precision nanomedicine.

NIR Light-Driving Barrier-Free Group Rotation in Nanoparticles with an 88.3% Photothermal Conversion Efficiency for Photothermal Therapy

Traditional photothermal therapy requires high-intensity laser excitation for cancer treatments due to the low photothermal conversion efficiency (PCE) of photothermal agents (PTAs). PTAs with ultra-high PCEs can decrease the required excited light intensity, which allows safe and efficient therapy in deep tissues. In this work, a PTA is synthesized with high PCE of 88.3% based on a BODIPY scaffold, by introducing a CF₃ "barrier-free" rotor on the meso-position (tfm-BDP). In both the ground and excited state, the CF₃ moiety in tfm-BDP has no energy barrier to rotation, allowing it to efficiently dissipate absorbed (NIR) photons as heat. Importantly, the barrier-free rotation of CF₃ can be maintained after encapsulating tfm-BDP into polymeric nanoparticles (NPs). Thus, laser irradiation with safe intensity (0.3 W cm^-2 , 808 nm) can lead to complete tumor ablation in tumor-bearing mice after intravenous injection of tfm-BDP NPs. This strategy of "barrier-free rotation" provides a new platform for future design of PTT agents for clinical cancer treatment.

Photocontrolled Iodine-Mediated Reversible-Deactivation Radical Polymerization: Solution Polymerization of Methacrylates by Irradiation with NIR LED Light

Herein, near-infrared (NIR) photocontrolled iodide-mediated reversible-deactivation radical polymerization (RDRP) of methacrylates, without an external photocatalyst, was developed using an alkyl iodide (e.g., 2-iodo-2-methylpropionitrile) as the initiator at room temperature. This example is the first use of a series of special solvents containing carbonyl groups (e.g., 1,3-dimethyl-2-imidazolidinone) as both solvent and catalyst for photocontrolled RDRP using long-wavelength (λ_max =730 nm) irradiation. The polymerization system comprises monomer, alkyl iodide initiator, and solvent. Well-defined polymers were synthesized with excellent control over the molecular weights and molecular weight distributions (M_w /M_n <1.21). The living features of this system were confirmed by polymerization kinetics, multiple controlled "on-off" light switching cycles, and chain extension experiments. Importantly, the polymerizations proceeded successfully with various barriers (pork skin and A4 paper), demonstrating the advantage of high-penetration NIR light.

Photothermally active nanoparticles as a promising tool for eliminating bacteria and biofilms

Bacterial contamination is a severe issue that affects medical devices, hospital tools and surfaces. When microorganisms adhere to a surface (e.g., medical devices or implants) they can develop into a biofilm, thereby becoming more resistant to conventional biocides and disinfectants. Nanoparticles can be used as an antibacterial agent in medical instruments or as a protective coating in implantable devices. In particular, attention is being drawn to photothermally active nanoparticles that are capable of converting absorbed light into heat. These nanoparticles can efficiently eradicate bacteria and biofilms upon light activation (predominantly near the infrared to near-infrared spectral region) due a rapid and pronounced local temperature increase. By using this approach new, protective, antibacterial surfaces and materials can be developed that can be remotely activated on demand. In this review, we summarize the state-of-the art regarding the application of various photothermally active nanoparticles and their corresponding nanocomposites for the light-triggered eradication of bacteria and biofilms.

Recent Progress of Rare-Earth Doped Upconversion Nanoparticles: Synthesis, Optimization, and Applications

Upconversion is a nonlinear optical phenomenon that involves the emission of high-energy photons by sequential absorption of two or more low-energy excitation photons. Due to their excellent physiochemical properties such as deep penetration depth, little damage to samples, and high chemical stability, upconversion nanoparticles (UCNPs) are extensively applied in bioimaging, biosensing, theranostic, and photochemical reactions. Here, recent achievements in the synthesis, optimization, and applications of UCNP-based nanomaterials are reviewed. The state-of-the-art approaches to synthesize UCNPs in the past few years are introduced first, followed by a summary of several strategies to optimize upconversion emissive properties and various applications of UCNPs. Lastly, the challenges and future perspectives of UCNPs are provided as a conclusion.

Fillers as Heaters for Photothermal Polymerization upon NIR Light

Photo-induced thermal polymerization upon near-infrared (NIR) light irradiation has been reported in the literature. In this approach, a component able to convert the NIR light into heat must be used in combination with a thermal initiator to initiate the free-radical polymerization of (meth)acrylates. In recent studies, some absorbers have been presented as very efficient heat generators (called heaters). In the present work, different fillers are investigated as heaters and compared to organic NIR absorbers. An alkoxyamine (e.g., BlocBuilder-MA) is used as thermal initiator and is dissociated by the heat generated by the NIR photoexcitation of the fillers. In the present work, several fillers are examined: graphene oxide, graphene nanoplatelets, multi-walled carbon nanotubes, and silicon carbide. Due to the energy of the photon delivered, NIR light curing is challenging but offers several advantages compared to visible light. The most interesting feature is the deeper penetration of the light inside the photocurable resin, enabling the polymerization of thick samples. Parallel to this, incorporation of fillers in resins allows unique access to composites through photothermal polymerization of (meth)acrylates. Three different wavelengths of irradiation have been studied: 785, 940, and 1064 nm.

Polymerization Assisted by Upconversion Nanoparticles under NIR Light

Photopolymerization of nanocomposite materials using near infrared light is one of the unique technologies based on the luminescent properties of lanthanide-doped upconversion nanoparticles (UCNPs). We explored the UCNP-triggered radical polymerization both in oligomer bulk and on the nanoparticle surface in aqueous dispersion. Core/shell UCNPs NaYF₄:Yb³⁺ and Tm³⁺/NaYF₄ with emitting lines in the ultraviolet and blue regions were used to activate a photoinitiator. The study of the bulk photopolymerization in an initially homogeneous reaction mixture showed the UCNP redistribution due to gradient density occurring in the volume, which led to formation of UCNP superlattices and spheres "frozen" in a polymer matrix. We also developed a strategy of "grafting from" the surface, providing polymer shell growth directly on the nanoparticles. The photosensitization of the endogenous water-soluble photoinitiator riboflavin by the resonance energy transfer from UCNPs was demonstrated in the course of monomer glycidyl methacrylate polymerization followed by photocrosslinking with poly(ethylene glycol) diacrylate on the nanoparticle surface.

Near-Infrared Irradiation Affects Lipid Metabolism in Neuronal Cells, Inducing Lipid Droplets Formation

It is known that lipids play an outstanding role in cellular regulation, and their dysfunction has been linked to many diseases. Thus, modulation of lipid metabolism may provide new pathways for disease treatment or prevention. In this work, near-infrared (NIR) light was applied to modulate lipid metabolism and increase intracellular lipid content in rat cortical neurons (RCN). Using label-free CARS microscopy, we have monitored the intracellular lipid content in RCN at a single-cell level. A major increase in average level of lipid per cell after treatment with laser diode at 808 nm was found, nonlinearly dependent on the irradiation dose. Moreover, a striking formation of lipid droplets (LDs) in the irradiated RCN was discovered. Further experiments and analysis reveal a strong correlation between NIR light induced generation of reactive oxygen species (ROS), lipids level, and LDs formation in RCN. Our findings can contribute to a development of therapeutic approaches for neurological disorders via NIR light control of lipid metabolism in neuronal cells.

Redox-responsive hyaluronic acid nanogels for hyperthermia- assisted chemotherapy to overcome multidrug resistance

Although chemotherapy has been widely used in the treatment of many kinds of cancer, drug resistance and side effects are the main obstacles in the cancer chemotherapy that result in an inferior therapeutic outcome. For the design of drug delivery system, extracellular stability and intracellular effective release are also a pair of contradictions. In this research, gold nanorods (AuNRs) loaded hyaluronic acid (HA) nanogels with reduction sensitivity were prepared for the efficient intracellular delivery of doxorubicin (DOX). The aforementioned HA-CysNG@AuNR nanogels with cystamine (Cys) as crosslinker could remain stable in the physiological condition and release DOX rapidly in the mimic intracellular glutathione (GSH) condition. Meanwhile, the cellular uptake efficiency by the human breast carcinoma (MCF-7) cells was enhanced because of the highly expressed HA receptor (CD44) on the cytomembrane. However, further cell experiments verified that it was difficult to achieve desired results for drug-resistant human breast cancer (MCF-7 ADR) cells due to the reduced drug uptake and enhanced drug efflux. Interestingly, this multidrug resistance of MCF-7 ADR cells could be reversed after treated with near-infrared (NIR) light. This might ascribe to the hyperthermia generated by AuNRs under NIR, which suspended drug efflux process and led to excellent hyperthermia-assisted chemotherapy outcome. Overall, our studies suggested that AuNRs loaded reduction-sensitive HA nanogels were excellent candidates of drug carriers to reverse the drug-resistance and induce severe apoptosis of drug-resistant MCF-7 ADR cells.

Temperature-controlled, phase-transition ultrasound imaging-guided photothermal-chemotherapy triggered by NIR light

Recently, nano-sized ultrasound contrast agents encapsulating drugs for cancer diagnosis and therapy have attracted much attention. However, the ultrasound signal of these agents is too weak to obtain an ideal ultrasound imaging effect. Furthermore, conventional ultrasound contrast agents with strong echo signal are not suitable for drug delivery against cancer because of their large size. To circumvent this problem, phase-transition ultrasound contrast agents are believed to be an excellent choice.

Methods: Liposomes co-encapsulating doxorubicin (DOX), hollow gold nanospheres (HAuNS), and perfluorocarbon (PFC) were synthesized by film dispersion method. The morphology, particle size, and stability of these liposomes (DHPL) were investigated. The photothermal effect, drug release, particle size change, cytotoxicity, and ultrasound imaging were studied by using the near infrared (NIR) light. Furthermore, tumor accumulation of DHPL was observed by in vivo fluorescence imaging and the antitumor effect was verified in a 4T1 tumor model.

Results: The nanosystem displayed a homogeneous size distribution (~200 nm) and an efficient light-to-heat conversion effect under 808 nm NIR laser irradiation. The nanometer size enabled considerable accumulation of DHPL in the tumor sites. The localized hyperthermia resulting from the photothermal effect of HAuNS could trigger the size transformation of DHPL followed by significant DOX release. Due to the gasification of PFC, a remarkably enhanced ultrasound signal was detected. DHPL also exhibited a prominent photothermally reinforced chemotherapeutic effect under the control of NIR light both in vitro and in vivo. Importantly, no systemic toxicity was observed by DHPL treatment.

Conclusion: In this study, we fabricated multi-functional perfluorocarbon liposomes for ultrasound imaging-guided photothermal chemotherapy which have the potential to serve as a prospective cancer treatment approach.

Hierarchical Nanocarriers for Precisely Regulating the Therapeutic Process via Dual-Mode Controlled Drug Release in Target Tumor Cells

A precisely controlled drug release is a great challenge in exploring methodologies of drug administration and fighting drug resistance for successful cancer chemotherapy. Herein, we developed a dual-mode nanocarrier to specifically deliver doxorubicin (Dox) and precisely control the drug release in target tumor cells. This hierarchical nanocarrier consisted of a gold nanorod as the heating core, biodegradable mesoporous silica as the storage chamber, and graphene quantum dot (GQD) as a drug carrier. The Arg-Gly-Asp peptides on the nanocarrier surface facilitated the specific interaction with integrin-overexpressed tumor cells and subsequent uptake via receptor-mediated endocytosis. Once exposed under the near-infrared (NIR) laser, the internalized nanocarrier rapidly heated the surrounding environment, which led to an instantaneous drug release by collapsing the π-π interaction between Dox and GQDs at high temperature and thereby intensified therapeutic efficacy. On the other hand, the silica shells underwent gradual degradation in the cellular matrix environment, along with stepwise liberation of the embedded GQD-Dox composites from the confined porous structure for the Dox release, exerting a long-term lethality to the tumor cells. By virtue of the physicochemical properties and synergistic behavior of the multiple components in this hierarchical nanocarrier, the NIR-triggered prompt release mode and the biodegradation-mediated slow release mode functioned in a precise and collaborative fashion, providing a promising way to manipulate the pharmacokinetics for precise cancer treatment.

Near-Infrared- and Visible-Light-Enhanced Metal-Free Catalytic Degradation of Organic Pollutants over Carbon-Dot-Based Carbocatalysts Synthesized from Biomass

Cost-efficient nanoparticle carbocatalysts composed of fluorescent carbon dots (CDs) embedded in carbon matrix were synthesized via one-step acid-assisted hydrothermal treatment (200 °C) of glucose. These as-synthesized CD-based carbocatalysts have excellent photoluminescence (PL) properties over a broad range of wavelengths and the external visible or NIR irradiation on the carbocatalysts could produce electrons to form electron-hole (e(-)-h(+)) pairs on the surface of carbocatalysts. These restant electron-hole pairs will react with the adsorbed oxidants/reducers on the surface of the CD-based carbocatalysts to produce active radicals for reduction of 4-nitrophenol and degradation of dye molecules. Moreover, the local temperature increase over CD-based carbocatalyst under NIR irradiation can enhance the electron transfer rate between the organic molecules and CD-based carbocatalysts, thus obviously increase the catalytic activity of the CD-based carbocatalyst for the reduction of 4-nitrophenol and the degradation of dye molecules. Such a type of CD-based carbocatalysts with excellent properties and highly efficient metal-free photocatalytic activities is an ideal candidate as photocatalysts for the reduction of organic pollutants under visible light and NIR radiation.

DNA-Hybrid-Gated Photothermal Mesoporous Silica Nanoparticles for NIR-Responsive and Aptamer-Targeted Drug Delivery

Near-infrared light is an attractive stimulus due to its noninvasive and deep tissue penetration. Particularly, NIR light is utilized for cancer thermotherapy and on-demand release of drugs by the disruption of the delivery carriers. Here we have prepared a novel NIR-responsive DNA-hybrid-gated nanocarrier based on mesoporous silica-coated Cu1.8S nanoparticles. Cu1.8S nanoparticles, possessing high photothermal conversion efficiency under a 980 nm laser, were chosen as photothermal agents. The mesoporous silica structure could be used for drug storage/delivery and modified with aptamer-modified GC-rich DNA-helix as gatekeepers, drug vectors, and targeting ligand. Simultaneously, the as-produced photothermal effect caused denaturation of DNA double strands, which triggered the drug release of the DNA-helix-loaded hydrophilic drug doxorubicin and mesopore-loaded hydrophobic drug curcumin, resulting in a synergistic therapeutic effect. The Cu1.8S@mSiO2 nanocomposites endocytosed by cancer cells through the aptamer-mediated mode are able to generate rational release of doxorubicin/curcumin under NIR irradiation, strongly enhancing the synergistic growth-inhibitory effect of curcumin against doxorubicin in MCF-7 cells, which is associated with a strong mitochondrial-mediated cell apoptosis progression. The underlying mechanism of apoptosis showed a strong synergistic inhibitory effect both on the expression of Bcl-2, Bcl-xL, Mcl-1, and upregulated caspase 3/9 activity and on the expression level of Bak and Bax. Therefore, Cu1.8S@mSiO2 with efficient synergistic therapeutic efficiency is a potential multifunctional cancer therapy nanoplatform.

Synthesis, Characterization, and Application in HeLa Cells of an NIR Light Responsive Doxorubicin Delivery System Based on NaYF4:Yb,Tm@SiO2-PEG Nanoparticles

Herein, we present a phototriggered drug delivery system based on light responsive nanoparticles, which is able to release doxorubicin upon NIR light illumination. The proposed system is based on upconversion fluorescence nanoparticles of β-NaYF4:Yb,Tm@SiO2-PEG with a mean diameter of 52±2.5 nm that absorb the NIR light and emit UV light. The UV radiation causes the degradation of photodegradable ortho-nitrobenzyl alcohol derivates, which are attached on one side to the surface of the nanoparticles and on the other to doxorubicin. This degradation triggers the doxorubicin release. This drug delivery system has been tested "in vitro" with HeLa cells. The results of this study demonstrated that this system caused negligible cytotoxicity when they were not illuminated with NIR light. In contrast, under NIR light illumination, the HeLa cell viability was conspicuously reduced. These results demonstrated the suitability of the proposed system to control the release of doxorubicin via an external NIR light stimulus.

Effect of near-infrared light exposure on mitochondrial signaling in C2C12 muscle cells

Near-infrared (NIR) light is a complementary therapy used to treat musculoskeletal injuries but the underlying mechanisms are unclear. Acute NIR light treatment (~800-950 nm; 22.8 J/cm(2)) induced a dose-dependent increase in mitochondrial signaling (AMPK, p38 MAPK) in differentiated muscle cells. Repeated NIR light exposure (4 days) appeared to elevate oxidative stress and increase the upstream mitochondrial regulatory proteins AMPK (3.1-fold), p38 (2.8-fold), PGC-1α (19.7%), Sirt1 (26.8%), and reduced RIP140 (23.2%), but downstream mitochondrial regulation/content (Tfam, NRF-1, Sirt3, cytochrome c, ETC subunits) was unaltered. Our data indicates that NIR light alters mitochondrial biogenesis signaling and may represent a mechanistic link to the clinical benefits.