Near-infrared Light Absorption Research Articles

Enhancement of the Lowering Effect on Energy Levels of LUMO by the Formation of B−N Dative Bond for Near‐infrared Light Absorption Properties Based on 1,3,4,6,8,9 b‐Hexaazaphenalene

AbstractWe illustrate the development of 1,3,4,6,8,9b‐hexaazaphenalene (6AP) derivatives which exhibit excellent near‐infrared (NIR) light absorption properties and deep LUMO levels. The electron‐withdrawing character of the 8‐nitrogen atom in the 6AP scaffold was enhanced by the introduction of a B−N dative bond. This formation of a boron‐nitrogen Lewis acid‐base pair succeeded in strengthening the electron‐withdrawing ability of the 8‐nitrogen atom, which induced the low‐lying LUMO levels of the resultant boron complexes. The data from UV−vis−NIR absorption spectroscopy and cyclic voltammetry suggested that these deep LUMO levels were the origins of the narrow HOMO−LUMO gap caused by selectively lowering the LUMO energy level. Furthermore, the enhancement of the molar absorption coefficients was observed in the boron complex compared to other azaphenalene derivatives in the previous reports. From theoretical calculations, the electron‐withdrawing character of the 8‐nitrogen atom induced the weak but substantial delocalization of the LUMO into the 7,9‐positions, where the LUMOs of other azaphenalene derivatives hardly exist. This electronic effect could influence the intrinsic symmetry forbidden character of electronic transition between the HOMO and the LUMO, resulting in the larger molar absorption coefficients by partially transforming to the allow character compared to those of other azaphenalene derivatives. In summary, the introduction of the boron‐nitrogen Lewis acid‐base pair into the π‐conjugated system of azaphenalene afforded the NIR light absorption properties with the ϵ reaching ∼104 M–1cm–1 and the deep LUMO levels around −4.0 eV (estimated by cyclic voltammetry).

Fabrication of light trapping structures specialized for near-infrared light by nanoimprinting for the application to thin crystalline silicon solar cells

Vehicle-integrated photovoltaics (VIPV) are gaining attention to realize a decarbonized society in the future, and the specifications for solar cells used in VIPV are predicated on a low cost, high efficiency, and the ability to be applied to curved surfaces. One way to meet these requirements is to make the silicon substrate thinner. However, thinner substrates result in lower near-infrared light absorption and lower efficiency. To increase light absorption, light trapping structures (LTSs) can be implemented. However, conventional alkali etched pyramid textures are not specialized for near-infrared light and are insufficient to improve near-infrared light absorption. Therefore, in this study, as an alternative to alkaline etching, we employed a nanoimprinting method that can easily fabricate submicron-sized LTSs on solar cells over a large area. In addition, as a master mold fabrication method with submicron-sized patterns, silica colloidal lithography was adopted. As a result, by controlling silica coverage, diameter of silica particles (D), and etching time (tet), the density, height, and size of LTSs could be controlled. At the silica coverage of 40%, D = 800 nm, and tet = 5 min, the reduction of reflectance below 65% at 1100 nm and the theoretical short-circuit current gain of 1.55 mA/cm2 was achieved.

NIR absorptive croconic acid/quercetin/CaO2 nanoplatform for tumor calcium overload therapy combined mild photothermal therapy

With excellent biocompatibility, stable chemical and optical properties, small organic molecules-based agents have always been a research hotspot in cancer photothermal therapy (PTT). In this work, a novel croconic acid-based molecule (CR) was designed and synthesized as an ideal photothermal agent (PTA), which showed abundant near-infrared (NIR) light absorption, high photothermal conversion ability, and excellent photothermal stability. By loading CR and quercetin (Qu) in CaO2, and coated with DSPE-PEG2000, a multifunctional theranostic nanoparticle (CCQ) was successfully prepared for calcium overloading mitochondrial metabolism inhibition synergetic mild PTT. Upon entering tumor microenvironment, CCQ can produce abundant H2O2 and a large amount of calcium ions, which lead to the imbalance of calcium concentration in the internal environment of tumor cells and induced mitochondrial apoptosis. With the existence of Qu, CCQ can effectively inhibit the expression of heat shock proteins (Hsp) during the PTT process, which weaken the heat resistance of tumors, ablate tumors at lower temperature (~45 °C), and reduce the damage to normal tissues. Guided by photoacoustic imaging (PAI), CCQ showed excellent multimodal therapeutic effect of tumors. This study provided a novel CR organic molecule-based theranostic nanoplatform that can be used to treat tumors via calcium overload therapy synergetic PTT at safe temperatures, which has promising potential for the future clinical cancer treatment.

Photonic Nanoparticles: Emerging Theranostics in Cancer Treatment

This review explores the potential of photonic nanoparticles for cancer theranostics. Photonic nanoparticles offer unique properties and photonics capabilities that make them promising materials for cancer treatment, particularly in the presence of near-infrared light. However, the size of the particles is crucial to their absorption of near-infrared light and therapeutic potential. The limitations and challenges associated with the clinical use of photonic nanoparticles, such as toxicity, immune system clearance, and targeted delivery to the tumor are also discussed. Researchers are investigating strategies such as surface modification, biodegradable nanoparticles, and targeting strategies to improve biocompatibility and accumulation in the tumor. Ongoing research suggests that photonic nanoparticles have potential for cancer theranostics, further investigation and development are necessary for clinical use.

Complete removal of 4-fluorophenol using a novel optical fiber photocatalysis–biodegradation–ion-adsorption system

To effectively remove 4-fluorophenol from water, a novel optical fiber photocatalysis–biodegradation–ion-adsorption reactor, which is composed of photocatalytic optical fibers, algal–bacterial biofilm, and ion-adsorption functionalized glass fiber cloth, was developed. The photocatalytic optical fibers, i.e., polymeric carbon nitride and lanthanum-doped TiO2 coated photocatalytic optical hollow fibers (POHFs), were located in the middle-layer of the reactor. POHFs have good ultraviolet–visible–near-infrared light absorption and photocurrent conversion capability and can rapidly oxidize 4-fluorophenol into biodegradable products. The S. obliquus biofilm was located on the top layer of the reactor and enriched by phototrophs (Limnothrix and Gemmatimonas) and heterotrophs (Blastomonas and Roseococcus), which continuously consume the photocatalytic products to accumulate biomass and provide dissolved oxygen through photosynthesis to generate advanced oxidation groups. The fluoride ion (F–) absorption material, which is composed of amyloid fibril/ZrO2/activated carbon nanoparticles, was coated on the glass fiber cloth. The prepared fiber cloth was located on the bottom layer of the reactor and has good F adsorption (the adsorption rate approaches 27.8 μM/L), which enables it to effectively remove the F− in water to avoid F− poisoning of the biofilm. The results showed that the developed fiber reactor can perform complete and rapid removal of 4-fluorophenol (for 160 mL, 0.44 mM 4-FP, totally removed in 20 h) and increase biomass production (increase up to 18.0 mg/day). Hence, it provides a smart method for the effective removal and conversion of 4-fluorophenol in water.

S/Se-Terchalcogenophene-C60 Dyads: Synthesis and Characterization of Optical and Photosensitizing Properties.

Fullerenes have been long investigated for application as singlet oxygen sources. Even though they possess high photosensitizing efficiency, their practical use is still limited, mostly because of insufficient absorption of visible and/or near-infrared light. This limitation can be overcome by introducing organic chromophores that absorb longer-wavelength light, either by covalent attachment to C60 or by its encapsulation in a polymeric matrix. In this work, we investigated the photosensitizing properties of the C60 molecule functionalized with organic units comprising thiophene or selenophene rings. The chemical structures of the synthesized dyads were characterized by nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry. The influence of the S/Se atoms and vinyl linkage between the organic unit and C60 on the absorptive and emissive properties of the dyads was investigated and correlated with their photosensitizing activity. For the latter, we used a standard chemical singlet oxygen trap. A selected dyad C60ThSe2 was also applied as a source of singlet oxygen in a model photocatalyzed synthesis of the fine chemical juglone from 1,5-dihydroxynapthalene.

Unraveling the role of defect types in Fe3O4 for efficient NIR-driven photocatalytic inactivation

Defect engineering is of great importance to tailor photocatalytic activity, which is uncertain in determining the antibacterial performance relationship with defect types. In this study, Fe3O4 nanoparticles with different vacancies were successfully prepared to investigate their distinct effects on the near-infrared (NIR) driven photocatalytic bacterial inactivation activity. Compared to the Fe3O4-1 with Fe-O vacancies, Fe3O4-2 with Fe-O–Fe vacancies contained improved photogenerated electron-hole separation efficiency and stronger adsorption ability to O2, and thus greatly facilitated the generation of reactive oxygen species (O2− and OH). Meanwhile, Fe3O4-2 with a narrow band gap can enhance NIR light absorption and the generation of heat. Moreover, Fe3O4-2 with Fe-O–Fe vacancies possessed enhanced bacteria-binding ability, thereby decreasing the diffusion distance of the released reactive oxygen species and heat, which could significantly accelerate bacterial killing. Owing to these tendencies, Fe3O4-2 fully inactivated 99% Escherichia coli (E. coli) and Bacillus subtilis (B. subtilis) within 10 min NIR irradiation, displaying better inactivation efficiency than Fe3O4-1. This study reveals the defect type-dependent photocatalytic behaviors, providing new insights into the antibacterial mechanisms of Fe3O4.

Efficient photothermal conversion for oxidation removal of formaldehyde using an rGO-CeO2 modified nickel foam monolithic catalyst

Photocatalysis is a feasible method for degrading indoor formaldehyde (HCHO) pollutants. To improve the purification efficiency and lower the cost of using noble metals as the primary component of the catalyst, synergistic catalysis involving two catalytic modes, such as thermocatalysis/photocatalysis, has attracted significant attention. In this study, a monolithic catalyst was prepared by loading reduced graphene oxide (rGO) and cerium dioxide (CeO2) on a nickel foam (NF) matrix. It was observed that the HCHO removal efficiency could be > 93 % under xenon light. The pre-deposited rGO on the NF matrix served as the photothermal conversion layer and contributed to the uniform and stable loading of CeO2. The surface temperature of this synthesized monolithic catalyst could rapidly rise to 170 °C. In addition, the heat was distributed evenly because of the increased near-infrared (NIR) light absorption caused by the added rGO and high electron mobility owing to the heat-conducting property of NF. At this temperature, the oxidation of HCHO was stimulated not only by the lattice oxygen of CeO2 but also by the production of O2– via oxidation by photogenerated electrons. In addition, O2– would reoxidize Ce3+ to Ce4+ on oxygen vacancies and accelerate the lattice oxygen consumption and supply cycle to reinforce the existing Mars-van Krevelen (MvK) mechanism.

High response plasma-enhanced graphene/GaAs near-infrared photodetector

In this paper, a graphene/GaAs near-infrared photodetector with Ag nanoparticles (NPs) is fabricated and the photoelectric characteristics of the device under near-infrared light is investigated. By spin-coating a 30 nm Ag NPs layer on the surface of the device, the local surface plasmon resonance (LSPR) of the Ag NPs can enhance the absorption of near-infrared light, thereby improving the sensitivity of the device. Compared with the device without Ag NPs, the responsivity of the device is significantly increased to 96 mA/W (increased by 1.6 times) under zero bias voltage at 808 nm near infrared light, the maximum detectivity of the device can be up to 4.72 × 1011cmHz1/2W−1. In addition, the response time (τr) and recovery time (τf) of the device are 28.21 μs/68.11 μs. The quantum efficiency of the detector is increased from 37% to 84% compared with the device without Ag NPs. This result shows the graphene/GaAs photodetectors have a broad application prospect in the field of near-infrared detection.

Facile synthesis of single-crystalline MnO2 nanowire arrays with high photothermal catalytic activity.

A simple process has been developed to form single-crystalline β-MnO2 nanowire arrays (NWAs) with a large surface area of 125 m2 g-1 on a glass plate working as a highly active three dimensional (3D) photothermal catalyst under the illumination of near infrared light due to the efficient light harvesting and heat confinement near the reaction field in addition to the large surface area.

Photobiomodulation therapy at red and near-infrared wavelengths for osteogenic differentiation in the scaffold-free microtissues.

One of the novel strategies for bone tissue regeneration is photobiomodulation (PBM) which depends on the red and near-infrared light absorption by mitochondria and may trigger bone tissue regeneration via the production of intracellular ROS and ATP, NO release, etc. It is also important to identify the changes in those signal molecule levels in an in vivo mimicking platform such as 3-Dimensional (3D) Scaffold Free Microtissues (SFMs) that may serve more natural osteogenic differentiation responses to PBM. Herein, we aimed to increase the osteogenic differentiation capability of the co-culture of Human Bone Marrow Stem Cells (hBMSC) and Human Umbilical Vein Endothelial Cells (HUVECs) on 3D SFMs by triple light treatment at 655 and 808-nm of wavelengths with the energy densities of 1, 3, and 5J/cm2. We performed the analysis of cell viability, diameter measurements of SFMs, intracellular ROS production, NO release, ATP activity, temperature measurements, DNA content, ALPase activity, calcium content, and relative gene expressions of ALP, Collagen, and Osteopontin by qRT-PCR. It was found that both wavelengths were effective in terms of the viability of SFMs. 1 and 5J/cm2 energy densities of both wavelengths increased the SFM diameter with significant changes in intracellular ROS, ATP, and NO levels compared to the control group. We concluded that PBM therapy was successful to induce osteogenesis. 1J/cm2 at 655nm of wavelength and 5J/cm2 at 808nm of wavelength were the most effective energy densities for osteogenic differentiation on SFMs with triple light treatment.

Rare-earth hydroxide/MXene hybrid: a promising agent for near-infrared photothermy and magnetic resonance imaging.

Layered gadolinium hydroxide (LGdH) and Ti3C2 monolayers were assembled into a LGdH/Ti3C2 (GTC) hybrid. The hybrid demonstrated enhanced near-infrared (NIR) light absorption properties and superior photothermal performance. Moreover, the GTC hybrid achieved an excellent T1-weighted magnetic resonance imaging (MRI) effect.

Fluorescence-guided colorectal surgery: applications, clinical results, and protocols.

In recent years, the rise of minimally invasive surgery has driven the development of surgical devices. Indocyanine green (ICG) fluorescence imaging is receiving increased attention in colorectal surgery for improved intraoperative visualization and decision-making. ICG, approved by the U.S. Food and Drug Administration in 1959, rapidly binds to plasma proteins and is primarily intravascular. ICG absorption of near-infrared light (750-800 nm) and emission as fluorescence (830 nm) when bound to tissue proteins enhances deep tissue visualization. Applications include assessing anastomotic perfusion, identifying sentinel lymph nodes, and detecting colorectal cancer metastasis. However, standardized protocols and research on clinical outcomes remain limited. This study explores ICG's role, advantages, disadvantages, and potential clinical impact in colorectal surgery.

Rational design of functionalized near-infrared absorbing phthalocyanines by three-component coupling strategy

Near-infrared (NIR) dyes are used in various applications such as organic solar cells and photodynamic therapy sensitizers. One example of a class of dyes, octa-arylthio-substituted phthalocyanines (Pcs), can effectively absorb NIR light above 800 nm. The substitution of the Pc’s peripheral sulfur effectively introduces extra functions without significant perturbation of the optical properties. However, the synthesis of phthalonitrile precursors containing various functionalized arylthio groups has been limited. Herein, we provide the three-component-type coupling reactions for synthesizing phthalonitriles with various functionalized chalcogen-aryl groups. Organometallic reagents were prepared from aryl halides, elemental chalcogen, and 3,6-bis(trifluoromethanesulfonyloxy)phthalonitrile can lead to functionalized phthalonitriles in a one-pot procedure. Commonly used methods were utilized to prepare the corresponding Pcs. This reaction can be extended to other group-16 elements, chemoselective organomagnesium, and organozincate reagents. The NIR absorption and fluorescence properties of Pcs were also revealed and rationalized under substitution effects.

Photovoltaic performance optimization of integrated perovskite/organic solar cells based on PM6:Y6 polymer non-fullerene system

Integrated perovskite/organic solar cells (IPOSCs) based on CH<sub>3</sub>NH<sub>3</sub>PbI<sub>3</sub>/PM6:Y6(BTP-4F) are successfully prepared through process innovation and thin film optimization technology. The quality of CH<sub>3</sub>NH<sub>3</sub>PbI<sub>3</sub>/PM6:Y6 mixed films is greatly optimized, and the interlayer ohmic contact is obtained by regulating the additive DIO and annealing treatment. At the same time, the mobility of holes and electrons in the organic layer in the near infrared region are, respectively, 8.3×10<sup>–3</sup> cm<sup>2</sup>/(V·s) and 8.8×10<sup>–3</sup> cm<sup>2</sup>/(V·s), which can match the mobility of holes and electrons in the visible perovskite layer, achieving the carrier transport balance in the microscopic pathway. The device has high short-circuit current density <i>J</i><sub>sc</sub> and high filling factor FF. In addition, by optimizing the mass ratio of polymer non-fullerene system PM6:Y6 to form a film, the density of non-radiation recombination sites and carrier recombination in the film are significantly reduced, making the extraction and transport of electrons and holes more efficient, and providing greater driving force to improve carrier transport. At the same time, a wider depletion region is formed to inhibit carrier recombination and increase the open-circuit voltage <i>V</i><sub>oc</sub>. The short-circuit current density of the optimized integrated solar cell increases to 25.88 A/cm<sup>2</sup>, the open-circuit voltage <i>V</i><sub>oc</sub> increases to 1.18 V, the filling factor FF reaches 80%, the optical response expands to 950 nm, the external quantum efficiency reaches 90% in the visible region, and the optimal energy conversion efficiency is as high as 24.42%. This is one of the highest efficiencies reported in IPOSCs. The results show that it is an effective method to enhance the near-infrared light absorption of perovskite solar cells and improve the performance of IPOSCs by combining the materials in visible region and the polymer non-fullerene system in near infrared region and optimizing the device structure. It lays a theoretical foundation for developing high efficiency IPOSCs in the future.

Thiophenol-spaced 2D coordination polymers with extraordinary alkali resistance and efficient photothermal conversion.

Coordination polymers (CPs) based on metal-sulfur bonds are rare; we herein realize a series of thiol-functionalized linker-based CPs (thiol-CPs), MTBT (M = Fe, Co and Zn; TBT = dehydrated 4,4'-thiobisbenzenethiol), which feature an anionic two-dimensional (2D) network, [M(TBT)2]n2n-, with the tetrahedral coordination unit {MS4} serving as a node. These compounds exhibit excellent hydrolytic stability, especially in alkaline solution (20M NaOH for five days), which is the highest value reported for CPs so far. In addition, among them, CoTBT displays favorable photo-thermal conversion effectiveness under an energy power of 0.5 W cm-2 808 nm laser irradiation for 15 s, with the temperature rising rapidly from room temperature to 135.2 °C.

A Janus Au-Polymersome Heterostructure with Near-Field Enhancement Effect for Implant-Associated Infection Phototherapy.

Polymer-inorganic hybrid Janus nanoparticles (PI-JNPs) have attracted extensive attention due to their special structures and functions. However, achieving the synergistic enhancement of photochemical activity between polymer and inorganic moieties in PI-JNPs remains challenging. Herein, the construction of a novel Janus Au-porphyrin polymersome (J-AuPPS) heterostructure by a facile one-step photocatalytic synthesis is reported. The near-field enhancement (NFE) effect between porphyrin polymersome (PPS) and Au nanoparticles in J-AuPPS is achieved to enhance its near-infrared (NIR) light absorption and electric/thermal field intensity at their interface, which improves the energy transfer and energetic charge-carrier generation. Therefore, J-AuPPS shows a higher NIR-activated photothermal conversion efficiency (48.4%) and generates more singlet oxygen compared with non-Janus core-particle Au-PPS nanostructure (28.4%). As a result, J-AuPPS exhibits excellent dual-mode (photothermal/photodynamic) antibacterial and anti-biofilm performance, thereby significantly enhancingthe in vivo therapeutic effect in an implant-associated-infection rat model. This work is believed to motivate the rational design of advanced hybrid JNPs with desirable NFE effect and further extend their biological applications.

Controlled Release of DNA Binding Anticancer Drugs from Gold Nanoparticles with Near-Infrared Radiation

Traditional chemotherapies target rapidly developing cells in the human body resulting in harsh side effects including fatigue, immune system suppression, and nausea, among others. Delivery systems to focus the active pharmaceutical ingredients (APIs) to the diseased tissue can diminish the negative side effects while improving treatment outcomes. Gold nanoparticles (AuNP) offer many unique advantages as drug delivery vehicles, including being biologically inert, easily adaptable to various shapes and sizes, able to create a strong Au-thiol bond, and able to generate heat upon the absorption of near-infrared light. To this end, a AuNP delivery vehicle was engineered to load and release two DNA binding anti-cancer drugs, mithramycin and doxorubicin, in a controlled fashion. The drugs were loaded onto the surface of the AuNP with temperature sensitive linkages. The amount of heat generated, and subsequent release of the drugs was controlled by the irradiation time with a near-infrared laser. By modulating the linkage used to load the drugs three different release profiles were able to be achieved, indicating the feasibility of such a system for combinational therapy requiring sequential release of APIs.

In situ facile one-step solvothermal synthesizing hexagonal ammonium tungsten bronze (NH4)0.33WO3 to tap NIR light absorption ability by controlling crystallinity

Tungsten bronze (TB) has potentially high visible light transparency and excellent near-infrared (NIR) shielding ability. To fully dig out the concealed optical properties of TB with specific chemical components, in this work, hexagonal ammonium tungsten bronze (h-ATB) (NH4)0.33WO3 was fabricated by a one-step solvothermal reaction. Through X-ray diffractometer (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and ultraviolet–visible–near infrared (UV–vis–NIR) spectroscopy to characterize h-ATB, which unraveled that controlling crystallinity could adjust the optical property of h-ATB. In particular, when the crystallinity of the h-ATB is over 95%, it exhibits the attractive NIR light shielding capability, which is in line with the predicted optical property via the first principle calculation based on density functional theory (DFT). Given the result, this work can provide a feasible research idea to explore the hidden optical properties of TB.

In-situ growth of amorphous MnO2 on C-decorated Fe-based geopolymer sphere with rich structure defects for efficient solar light-induced photo-thermal-Fenton reaction

• A-MnO 2 /C-FeGS with rich structure defects was constructed as a photo-Fenton catalyst. • Highly stable and reactive A-MnO 2 was fabricated via ion exchange anchoring strategy. • Manganese residue was used as the source of Fe and Si for environmental remediation. • A-MnO 2 and C triggered photo-thermal conversion and lattice oxygen activation. • Photo-thermal synergy promoted photo-Fenton activity for tetracycline degradation. Crystalline MnO 2 exhibits excellent photo-thermal conversion and adjustability of valence states properties, but the weak near-infrared light absorption, poor charge transportation and utilization limit its environmental applications. Herein, a novel Na-doped amorphous MnO 2 /C-decorated Fe-based geopolymer sphere (A-MnO 2 /C-FeGS) with rich structure vacancies was constructed by ion exchange anchoring strategy and used to degrade tetracycline hydrochloride (TC) in solar light-induced photo-thermal-Fenton process. Manganese residue (MR), an industrial solid waste, was used as the source of Fe and Si. A-MnO 2 /C-FeGS exhibited excellent catalytic performance with TC removal of 98.2% within 30 min, being about 4.5 and 3.3 times faster than crystalline MnO 2 and C-FeGS, respectively. The improved photocatalytic activity was attributed to that rich oxygen vacancies could provide more catalytic active sites and accelerate Fe 3+ /Fe 2+ and Mn 4+ /(Mn 2+ +Mn 3+ ) conversion for more ·OH generation. Moreover, Na-doped amorphous MnO 2 and C decoration synergistically contributed to high photo-thermal conversion rate, which could in-situ heat the catalyst and induce the activation of H 2 O 2 . This promoted the activation of the surface lattice oxygen and accelerated the secondary transition and utilization of the thermal electrons captured by the defect sites. This work provides a novel strategy for the development of highly reactive catalysts and valorization of MR in the field of environmental remediation.