Near-infrared Research Articles

Unravelling Kinetics of Intramolecular NdIII → FeII Energy Transfer in Spin Crossover Single Molecules: Dotting the i's and Crossing the t's.

Compared with the ripple of visible EuIII-based emission intensity induced by appended [FeIIN6] spin crossover (SCO) units, as detected in the triple-stranded [EuFe(L1)3]5+ helicate, the lanthanide-based luminescent detection of FeII spin-state equilibria could be improved significantly if the luminophore emission is shifted toward the near-infrared (NIR) domain. Replacing EuIII with NdIII in [NdFe(L1)3]5+ (i) maintains the favorable SCO properties in acetonitrile [critical temperature T1/2 = 322(2) K], (ii) saturates nonradiative vibrational relaxation processes in the 233-333 K range, and (iii) boosts the crucial intramolecular NdIII → FeII energy transfer rate processes, which are sensitive to the spin state of the FeII metallic center. Consequently, the steady-state NIR Nd(4F3/2 → 4IJ) emission of the luminophore is amplified and linearly correlated with the low-spin-[FeIIN6] and high-spin-[FeIIN6] mole fractions controlled by the SCO equilibrium. This paves the way for a straightforward and direct NIR luminescent reading/sensing of the FeII spin state in single molecules.

Deciphering the Nd3+ environment and energy-transfer mechanisms in thermally stable novel calcium aluminate glasses: elucidation of broadband high-gain performance for laser applications

Rare-earth-doped barium calcium aluminate (BCA) glasses, having extended infrared (IR) transmission (6 μm), are attractive materials for near IR (NIR) photonic applications. Nd2O3-doped BCA glasses display broadband emission at 1.07 µm, but they are limited, with poor glass-forming ability (GFA) and low emission cross sections. In the present study, four different barium zinc calcium aluminate (BZCA) glasses are synthesized with varied ZnO concentrations (from 9.5 to 24.5 mol%) and doped with 0.5 mol% Nd2O3 to decipher the effect on GFA and spectroscopic properties. The addition of ZnO enhances the GFA, and the NdBZCA20 glass shows the maximum GFA. Ultraviolet (UV)–visible (Vis)–NIR absorption spectra reveal a decreasing trend in the nephelauxetic effect, while J–O parameters, emission, and gain properties lead to no significant alteration with increasing ZnO, and the structure–properties correlation is established accordingly. However, the emission cross sections for all ZnO concentrations are found ∼4.5 × 10−20 cm2 accompanied by broadband emission (Δλ eff ∼ 40 nm), which ensures the potentiality of these glasses for low-threshold high-gain laser applications as well as ultrashort pulse laser applications. Furthermore, a thorough analysis of 1.06 µm emission as a function of Nd concentration in the BZCA20 glass is reported here. The emission spectra and decay time indicate that 0.5 mol% is the optimized doping concentration. Inokuti–Hirayama and Burshtein equations are adopted to study the decay kinetics and energy-transfer mechanisms, which confirm that the energy-transfer process due to cross-relaxation is dominant up to 0.5 mol% concentration, whereas, beyond that concentration, excitation energy migration via the hopping mechanism supersedes.

Deciphering the imprint of active galactic nucleus feedback in Seyfert galaxies. Nuclear-scale molecular gas deficits

We study the distribution of cold molecular gas in the circumunuclear disks (CND; $r pc) of a sample of 64 nearby L $=7-45 Mpc) disk galaxies ---including 45 active galactic nuclei (AGN) and 19 nonAGN--- for which high-spatial-resolution (median value $ pc) multiline CO interferometer observations have been obtained at millimeter wavelengths with the Atacama Large Millimeter Array (ALMA) and/or Plateau de Bure Interferometer (PdBI). We decipher whether or not the concentration and normalized radial distribution of cold molecular gas change as a function of X-ray luminosity in the 2--10 keV range X $) in order to analyze the imprint left by AGN feedback. We also look for similar trends in the concentration and normalized radial distribution of the hot molecular gas and in the hot-to-cold-molecular gas mass ratio in a subset of 35 galaxies using near-infrared (NIR) integral field spectroscopy data obtained for the H$_2$ 1-0 S(1) line. We find a significant turnover in the distribution of the cold molecular gas concentration as a function of X-ray luminosity with a breakpoint that divides the sample into two branches: (1) the `AGN build-up branch'' ($L_ X pm0.3 $erg s$^ $) and (2) the ``AGN feedback branch'' ($L_ X pm0.3 $erg s$^ $) . Lower-luminosity AGN and nonAGN of the AGN build-up branch show high cold molecular gas concentrations and centrally peaked radial profiles on nuclear ($r pc) scales. Higher-luminosity AGN of the AGN feedback branch show a sharp decrease in the concentration of molecular gas and flat or inverted radial profiles. The cold molecular gas concentration index ($CCI$) --- defined as the ratio of surface densities at $r pc ($ gas $) and $r pc $( gas $), namely $CCI gas gas $)--- spans a 0.63 dex range, equivalent to a factor simeq 4-5, between the galaxies lying at the high end of the AGN build-up branch and the galaxies showing the most extreme nuclear-scale molecular gas deficits in the AGN feedback branch. The concentration and radial distributions of the hot molecular gas in our sample follow qualitatively similar but less extreme trends as a function of X-ray luminosity. As a result, we find higher values of hot-to-cold molecular gas mass ratios on nuclear scales in the highest luminosity AGN sources of the AGN feedback branch. These observations confirm ---with a three times larger sample--- previous evidence found in the context of the Galaxy Activity Torus and Outflow Survey (GATOS) that the imprint of AGN feedback on the CND-scale distribution of molecular gas is more extreme in higher luminosity Seyfert galaxies of the local Universe.

Iron/Molybdenum Sulfide Nanozyme Cocatalytic Fenton Reaction for Photothermal/Chemodynamic Efficient Wound Healing.

The issue of bacterial infectious diseases remains a significant concern worldwide, particularly due to the misuse of antibiotics, which has caused the emergence of antibiotic-resistant strains. Fortunately, the rapid development of nanomaterials has propelled significant progress in antimicrobial therapy, offering promising solutions. Among them, the utilization of nanoenzyme-based chemodynamic therapy (CDT) has become a highly hopeful approach to combating bacterial infectious diseases. Nevertheless, the application of CDT appears to be facing certain constraints for its low efficiency in the Fenton reaction at the infected site. In this study, we have successfully synthesized a versatile nanozyme, which was a composite of molybdenum sulfide (MoS2) and iron sulfide (FeS2), through the hydrothermal method. The results showed that iron/molybdenum sulfide nanozymes (Fe/Mo SNZs) with desirable peroxidase (POD) mimic activity can generate cytotoxic reactive oxygen species (ROS) by successfully triggering the Fenton reaction. The presence of MoS2 significantly accelerates the conversion of Fe2+/Fe3+ through a cocatalytic reaction that involves the participation of redox pairs of Mo4+/Mo6+, thereby enhancing the efficiency of CDT. Additionally, based on the excellent photothermal performance of Fe/Mo SNZs, a near-infrared (NIR) laser was used to induce localized temperature elevation for photothermal therapy (PTT) and enhance the POD-like nanoenzymatic activity. Notably, both in vitro and in vivo results demonstrated that Fe/Mo SNZs with good broad-spectrum antibacterial properties can help eradicate Gram-negative bacteria like Escherichia coli and Gram-positive bacteria like Staphylococcus aureus. The most exciting thing is that the synergistic PTT/CDT exhibited astonishing antibacterial ability and can achieve complete elimination of bacteria, which promoted wound healing after infection. Overall, this study presents a synergistic PTT/CDT strategy to address antibiotic resistance, providing avenues and directions for enhancing the efficacy of wound healing treatments and offering promising prospects for further clinical use in the near future.

Construction of Rod-Like Bi4O5I2/NaYF4:Yb,Tm Composite and its Improved Photocatalytic Degradation Performance Under Near-Infrared Light

Photocatalytic technology exhibits promising prospects in environmental remediation owing to its sustainable and environmentally friendly advantages. Among the bismuth-rich halide oxides, Bi4O5I2 has demonstrated remarkable efficacy in dye degradation due to its favorable valence band and conduction band positions. In this study, we successfully synthesized Bi4O5I2/NaYF4:Yb,Tm composites through a solvothermal method. When exposed to visible light, the Bi4O5I2/NaYF4:Yb,Tm composite achieved an impressive degradation rate of 86.7% for RhB solution after 60[Formula: see text]min of light-induced reaction. Moreover, the incorporation of NaYF4:Yb,Tm into Bi4O5I2 extended the utilization of near-infrared (NIR) spectroscopy. Under 980[Formula: see text]nm NIR light irradiation, the degradation rate of Rhodamine B (RhB) solution by the Bi4O5I2/NaYF4:Yb,Tm composite reached 43.0% after 240[Formula: see text]min of light reaction. Free radical capture experiments confirmed that h[Formula: see text] and •[Formula: see text] O[Formula: see text] played a significant role as the primary active species in the degradation process of RhB by the Bi4O5I2/NaYF4:Yb,Tm composites. Furthermore, we explored the mechanism behind the photocatalytic degradation of RhB solution using the Bi4O5I2/NaYF4:Yb,Tm composites. Bi4O5I2/NaYF4:Yb,Tm holds great potential as a promising candidate for utilization of NIR light for photocatalytic reactions.

Interface Allocation Precisely Customized Janus Upconversion Nanomotor for Atherosclerosis Amelioration

AbstractSpatial and temporal precisely control of direction and speed is crucial for nanomotors to enable complex operations and applications in microsurgery, drug delivery, isolation of biological targets, and so on. Judicious material design involving Janus nanoparticles has been popular over the past decades, however, precise and customizable modulation of Janus structure with a specific asymmetric ratio for motion control is still challenging. In this study, a universal “interface allocation” strategy is developed for efficient and controllable preparation of Janus mesoporous silica‐coated upconversion nanoparticles (Janus UCNP@mSiO2) with precisely tuned asymmetric ratio to achieve near‐infrared (NIR)‐controlled active mobility for relieving vessel plaque. Mesoporous silica with a thickness of 50 nm is precisely coated onto the nanoparticles’ surface with an optimal coverage ratio of 50% to encapsulate gas propellant. Upon exposure to upconverted blue light, the nanomotors release nitric oxide, facilitating their motion and pathologically improving atherosclerosis through endothelium‐dependent vasodilation. Experimental and theoretical simulation results demonstrate the advantages of NIR‐controlled Janus upconversion nanomotors in atherosclerosis treatment, including enhanced nanoparticle‐transmittance rate (34.83% to 85.57%) and excellent in vivo therapeutic efficacy.

Blend uniformity monitoring in a continuous manufacturing mixing process for a low-dosage formulation using a stream sampler and near infrared spectroscopy

Continuous manufacturing has the potential to offer several benefits for the production of oral solid dosage forms, including reduced costs, low-scale equipment, and the application of process analytical technology (PAT) for real-time process control. This study focuses on the implementation of a stream sampler to develop a near infrared (NIR) calibration model for blend uniformity monitoring in a continuous manufacturing mixing process. Feeding and mixing characterizations were performed for three loss-in-weight feeders and a commercial continuous mixer to prepare powder blends of 2.5–7.5 % w/w ibuprofen DC 85 W with a total throughput of 33 kg/h. The NIR spectral acquisition was performed after the mixing stage using a stream sampler for flowing powders. A continuous mixer shaft speed of 250 RPM was selected to operate the mixing process based on a variability analysis developed with in-line spectral data acquired using the stream sampler at 6 RPM. A partial least squares regression (PLS-R) model was performed and evaluated, yielding a root-mean-square error of prediction (RMSEP) of 0.39 % w/w and a bias of 0.05 % w/w. An independent experimental run conducted two days later revealed that the continuous mixing process and the NIR calibration model presented low day-to-day variation. The minimum practical error (MPE) and sill values through variographic analysis showed low variance associated with the sampling process using the stream sampler. Results demonstrated the promising capacity of the stream sampler coupled to an NIR probe to be implemented within continuous manufacturing processes for the real-time determination of API concentration.

In-situ growth of Cs0·33WO3@ATO composite material with enhanced NIR shielding rate for energy-saving coating

Driven by the global goal of “carbon neutrality”, energy conservation, emission reduction and low-carbon development have become important research directions. Transparent thermal insulation materials can effectively shield near-infrared radiation while maintaining high visible light transmittance, making them widely applicable in building energy conservation. In this paper, antimony-doped tin oxide (ATO) and cesium tungsten bronze (CsxWO3, or CWO) are chosen to be composited in order to solve the problems of the poor shielding effect of ATO for short-wavelength near-infrared (NIR) light and the unsatisfactory shielding effect of CWO for long-wavelength NIR light. Therefore, in this study, we employed a one-step hydrothermal method to form a novel CWO@ATO core-shell structure to combine the advantages of both ATO and CWO. By adjusting the composite ratio of ATO and CWO, both the physical and electronic stucutres are effectively tuned to promote the optical modulation in a broad bandwidth. Enventually, the core-shell structured composite exhibit an excellent near-infrared blocking property, surpassing the pure ATO by 27.8 % in the wavelength region of 780∼1500 nm while improving by 14.9 % compared to CWO in the long wavelength between 1500 and 2500 nm. Furthermore, the prepared CWO@ATO core-shell structure repesents near-infrared shielding rate as high as 93.1 % in the full NIR spectrum, and possesses an overall thermal insulation coefficiency (THI) of 9.33 in the full range from 780 nm to 2500 nm, which is substantially larger than that of pure ATO and CWO by a factor of 2.37 and 3.05, respectively. This core-shell structure engineering realizes the utilization of complementary advantages of ATO and Cs0·33WO3 materials, providing a new method to improve the near-infrared performance of energy-saving glass coating, and having broad application prospects in the field of low-carbon buildings.

Proof of a LOD prediction model with orthogonal PAT methods in continuous wet granulation and drying

Real-time monitoring of critical quality attributes, such as residual water in granules after drying which can be determined through loss-on-drying (LOD), during wet granulation and drying is essential in continuous manufacturing. Near-infrared (NIR) spectroscopy has been widely used as process analytical technology (PAT) for in-line LOD monitoring. This study aims to develop and apply a model for predicting the LOD based on process parameters. Additionally, the efficacy of an orthogonal PAT approach using NIR and mass balance (MB) for a vibrating fluidized bed dryer (VFBD) is demonstrated. An in-house-built, cost-effective NIR sensor was utilized for measurements and exhibited good correlation compared to standard method via infrared drying. The combination of NIR and MB, as independent methods, has demonstrated their applicability. A good correlation, with a Pearson r above 0.99, was observed for LOD up to 16 % (w/w). The use of an orthogonal PAT method mitigated the risk of false process adaption. In some experiments where the NIR sensor might have been covered by powder and therefore did not measure accurately, LOD monitoring via MB remained feasible. The developed model effectively predicted LOD or process parameters, resulting in an R2 of 0.882 and a RMSE of 0.475 between predicted and measured LOD using the standard method.

Tunable optical properties of graphene wrapped ZnO@Ag spherical core-shell nanoparticles

In this paper, we studied theoretically and numerically the material’s response to incident electromagnetic wave of graphene wrapped zinc-oxide/silver (g − ZnO@Ag) core–shell spherical nanoparticles embedded in a dielectric host matrix. As the nanoparticles size is ∼30 nm, a size much smaller than the wavelength of light, the quasi-static approximation is utilized to obtain analytical expressions for the electric polarizability and the corresponding extinction cross-section. It is found that the spectra of the extinction cross-section of g − ZnO@Ag nanoparticles exhibit two sets of localized surface resonance peaks in the visible and near infra-red (NIR) spectral regions. The first set of peaks observed below ∼900 nm are due to the coupling of the energy gap of the ZnO core with the local surface plasmon resonances of Ag shell, and the second set of graphene-assisted narrow peaks located in the NIR region (above ∼900 nm) are attributed to the plasmons excited at the Ag/graphene interface. It is found that the intensity of the extinction cross-section as well as the positions of the resonance wavelengths are interesting that the graphene-assisted narrow peaks are strongly dependent on the number of layers (N g ) and the chemical potential (μ) of graphene. It means that the response of ZnO@Ag core–shell nanoparticles to electromagnetic fields are greatly enhanced when it is wrapped with graphene and can also be tuned in the therapeutic NIR spectral region by varying N g and μ. The results may be used for possible application in the medical fields, especially for cancer detection and drug delivery.

The photothermal coupling of TiN@Au core-shell nanorods applied to near-infrared photothermal therapy

Thermal plasmonic nanoparticles offer a novel and significant approach for photothermal therapy in the medical field, which is photothermal therapy of cancer. This study introduces a type of core-shell nanorods with internal coupling of titanium nitride (TiN) and gold (Au) nanomaterials. The photothermal properties of these nanorods in the near infrared (NIR) band were investigated using COMSOL Multiphysics software and the finite element method. Results indicate that TiN@Au and Au@TiN core-shell nanorods exhibit superior photothermal properties in the NIR band compared to pure TiN nanorods of similar volume. Furthermore, core-shell nanorods with polarization angles of 0° and 45° demonstrate enhanced optical absorption properties in the near infrared range. Furthermore, the study on the tunability of localized surface plasmon resonance with variations in core diameter, shell thickness, and combined changes of core diameter and shell thickness for core-shell nanorods of equal volume suggests that TiN@Au core-shell nanorods with a 10 nm Au shell offer increased optical absorption efficiency and photothermal conversion capability. Ultimately, the TiN and Au core-shell nanorods proposed in this research offer valuable insights for the structural design and heat transfer control of nanoparticle heat generators to enhance fluid temperature, as well as provide practical guidance for the preparation of core-shell nanoparticles.

Design of an intelligent Near-Infrared responsive antibacterial Nano-Platform based on MoS2/Cu3Mo2O9

In this era of high drug resistance, there is an urgent need for novel antimicrobial agents and strategies to achieve smarter sterilization effects. However, developing an environmentally friendly, controllable, and self-cleaning smart antimicrobial material remains a formidable challenge. In this work, a smart antimicrobial nanoplatform composed of Cu3Mo2O9 and MoS2 has been successfully designed and synthesized. The computational findings reveal that, owing to the interfacial coupling between the two substances at the solid junction, this architecture can effectively absorb near-infrared light, significantly reduce migration resistance, and improve carrier separation efficiency. Empirical observations demonstrate that with a sample concentration of 100 μg/mL, under near-infrared (NIR) laser irradiation, the microenvironmental temperature proximal to the bacteria can be swiftly elevated from 28.6 °C to in excess of 50 °C within a mere 6 min. The overall photothermal conversion efficiency is 32.6 %, and it exhibits an active oxygen level nearly 5 times higher than that of Cu3Mo2O9. Furthermore, the permeability of the cell membrane was greatly improved with the increased temperature, which is beneficial for the generated reactive oxygen species (ROS) entering the bacterial cells. After synergistic antimicrobial treatment, the antibacterial rate against Escherichia coli can reach over 99 %. More importantly, this nano-platform features a unique ’activation’ mechanism that uses NIR as an ’activation switch’ to selectively toggle between ’passive defense,’ ’secondary sterilization,’ and ’active attack’ antibacterial modes as needed. Upon interaction with aqueous environments, its reusability and favorable biocompatibility with terrestrial and aquatic life promise to facilitate the intelligent eradication of deleterious microorganisms in aquatic systems via the diurnal cycle of sunrise and sunset. This is highly significant for the ongoing management and maintenance of public resources such as amusement parks, artificial fish ponds, and urban water features.

Broadband sensitized near-infrared emission in Eu2+-Nd3+ co-doped BaAl2O4 as a potential spectral modulator for silicon solar cells.

The near-infrared (NIR) down-conversion process for broadband sensitization has been studied in Eu2+-Nd3+ co-doped BaAl2O4. This material has a broad absorption band of 200-480 nm and can convert photons in the visible region into NIR photons. The NIR emission at 1064 nm, attributed to the Nd3+:4F3/2 → 4I11/2 transition, matches the bandgap of Si, allowing Si solar cells to utilize the solar spectrum better. The energy transfer (ET) process between Eu2+ and Nd3+ was demonstrated using photoluminescence spectra and luminescence decay curves, and Eu2+ may transfer energy to Nd3+ through the cooperative energy transfer (CET) to achieve the down-conversion process. The energy transfer efficiency (ETE) and theoretical quantum efficiency (QE) were 68.61% and 156.34%, respectively, when 4mol% Nd3+ was introduced. The results indicate that BaAl2O4:Eu2+-Nd3+ can serve as a potential modulator of the solar spectrum and is expected to be applied to Si solar cells.

A NIR-to-NIR non-emissive rare-earth nanoprobe that specifically lights-up inflammatory condition in vivo

Development of exquisitely selective and sensitive HClO/ClO– sensor in living system is of the utmost importance. To achieve near-infrared (NIR)-responsive detection of HClO/ClO–, a new nanoprobe (csUCNP-Cy820) is composed of the ClO–-sensitive Cy820 (energy acceptor), and NaLuF4:20%Yb,1%Tm@NaLuF4 core@shell upconversion nanoparticles (csUCNP, energy donor) capable of emitting NIR upconversion luminescence (UCL) of Tm3+ (800 nm). Through the mechanism of Förster resonance energy transfer (FRET), the UCL emission can be recovered in the presence of HClO/ClO–. The csUCNP-Cy820 nanoprobe is effectively adapted as a precise ClO– detection sensor with a low limit of detection (LoD) of 58 nmol/L in vitro. Moreover, owing to excitation and emission wavelengths both falling within the NIR region, the nanoprobe facilitates high quality imaging in mice models of peritonitis and arthritis, thereby enabling deeper penetration depth for imaging detection in vivo.

A NIR iridium(III) complex-based luminescence probe for imaging mitochondria pyruvate dehydrogenase kinase 1 in triple-negative breast cancer cells

The aberrant expression of mitochondrial pyruvate dehydrogenase kinase 1 (PDK1) is highly associated with tumorigenesis and metastasis of triple-negative breast cancer (TNBC). However, because of the dearth of highly sensitive and targetable probes for PDK1, the precise imaging of mitochondrial PDK1 in TNBC cells remains challenging. We herein describe the first near-infrared (NIR) luminescence probe for visualizing PDK1 in TNBC living cells through conjugating a PDK1 inhibitor, dichloroacetic acid (DCA), to an iridium(III) complexes. This probe retains not only the favorable optical characteristics of iridium(III) complexes, but also the specific binding ability of DCA for PDK1. The probe can sensitively and specifically detect mitochondria PDK1 in TNBC cells, as verified by cellular thermal shift assay (CETSA), knockdown and selectivity experiments. Moreover, complex 1 has the capability for imaging TNBC spheroids and zebrafish models with good imaging contrast and penetration, presumably benefiting from its PDK1 target ability and NIR property. Importantly, the probe shows negligible luminescence in normal cell lines with low expression of PDK1, demonstrating its ability to discriminate TNBC cells from normal cells. This probe, which acts through the interplay of both low oxygen diffusion and a rigid microenvironment upon binding to PDK1, could provide mechanistic insights into the biological roles of PDK1 in TNBC and support the development of PDK1-based TNBC diagnostic probes in vivo.

Photo-induced collective charge-density-wave dynamics in bulk 1T-VSe2

We investigated temperature (T) and excitation density dependent ultrafast near-infrared (NIR) transient reflectivity dynamics in the charge density wave (CDW) phases of bulk layered 1T-VSe2 using NIR and visible excitations. The data reveal fingerprints of conventional non-adiabatic CDW collective dynamics with rather fast electronic order parameter dynamics showing sub-picosecond suppression and recovery. The slower T-dependent 100-ps dynamics indicates rather isotropic heat transport dominated by the lattice degrees of freedom.

NIR activated upconversion based nanocatalysts for CT/PA imaging-guided triple synergistic PTT/PDT/CDT cancer treatment

Photodynamic therapy (PDT), as a non-invasive treatment, is expected to be widely used in clinical cancer treatment. In this paper, a near-infrared (NIR) light responsive Lu2O3:Yb/Er/Li-Ce6@MIL-101/GOx-PDA (LCMGP) nanodiagnostic platform was prepared for CT/PA imaging-guided multimodality synergistic therapy. Under 808 nm laser irradiation, Lu2O3:Yb/Er/Li-Ce6 (LC) NPs in the nano-diagnostic platform are activated and sensitized by NIR light, resulting in the generation of more single-linear oxygen (1O2) for efficient PDT. Glucose oxidase (GOx) and MIL-101 (Fe) nanozymes can utilize their excellent enzyme cascade catalytic properties and peroxidase-like catalytic properties to undergo glycolysis reactions and catalyze the decomposition of endogenous hydrogen peroxide (H2O2), producing a large amount of hydroxyl radicals (•OH), achieving efficient chemodynamic therapy (CDT). The functionalized modification of polydopamine (PDA) endows the LCMGP nanoparticles with higher photothermal conversion efficiency, which can prompt high local temperature at the tumor site under the irradiation of NIR light to achieve efficient photothermal therapy (PTT). In addition, hyperthermia accelerates the catalytic efficiency of the nanozymatic cascade of LCMGP nanoparticles to enhance ROS production while increasing cellular uptake, resulting in PTT-induced PDT/CDT synergistic effect (96%). Based on the excellent photothermal conversion effect of PDA and the high X-ray attenuation effect of Lu/Fe, the LCMGP nanotherapeutic system demonstrates good CT/PA imaging function, providing new insights and ideas for imaging-mediated multimodal synergistic therapy.

Thermal effects and biological response of breast and pancreatic cancer cells undergoing gold nanorod-assisted photothermal therapy

To increase the therapeutic efficacy of nanoparticle (NP)-assisted photothermal therapy (PTT) and allow for a transition toward the clinical setting, it is pivotal to characterize the thermal effect induced in cancer cells and correlate it with the cell biological response, namely cell viability and cell death pathways. This study quantitatively evaluated the effects of gold nanorod (GNR)-assisted near-infrared (NIR) PTT on two different cancer cell lines, the 4 T1 triple-negative breast cancer cells and the Pan02 pancreatic cancer cells. The interaction between nanomaterials and biological matrices was investigated in terms of GNR internalization and effect on cell viability at different GNR concentrations. GNR-mediated PTT was executed on both cell lines, at the same treatment settings to allow a straightforward comparison, and real-time monitored through thermographic imaging. A thermal analysis based on various parameters (i.e., maximum absolute temperature, maximum temperature change, temperature variation profile, area under the time-temperature change curve, effective thermal enhancement (EFE), and time constants) was performed to evaluate the treatment thermal outcome. While GNR treatment and NIR laser irradiation alone did not cause cell toxicity in the selected settings, their combination induced a significant reduction of cell viability in both cell lines. At the optimal experimental condition (i.e., 6 μg/mL of GNRs and 4.5 W/cm2 laser power density), GNR-assisted PTT reduced the cell viability of 4 T1 and Pan02 cells by 94% and 87% and it was associated with maximum temperature changes of 25 °C and 29 °C (i.e., ~1.8-fold increase compared to the laser-only condition), maximum absolute temperatures of 55 °C and 54 °C, and ETE values of 78% and 81%, for 4 T1 and Pan02 cells, correspondingly. Also, the increase in the GNR concentration led to a decrease in the time constants, denoting faster heating kinetics upon irradiation. Furthermore, the thermal analysis parameters were correlated with the extent of cell death. Twelve hours after NIR exposure, GNR-assisted PTT was found to mainly trigger secondary apoptosis in both cell lines. The proposed study provides relevant insights into the relationship between temperature history and biological responses in the context of PTT. The findings contribute to the development of a universal methodology for evaluating thermal sensitivity upon NP-assisted PTT on different cell types and lay the groundwork for future translational studies.

Construction of a MoS2@mSiO2 nanocarrier as a near-infrared/pH dual-responsive platform to control the drug release for anti-tumor

Designing new-type nanosystems to realize the combination of multiple treatment is an efficient routine to enhance the anti-tumor efficacy in clinic. In this study, molybdenum disulfide (MoS2) was selected as a photothermal agent, and mesoporous silica (mSiO2) was coated on the surface of MoS2 using the solvothermal and template removal methods. The chemotherapeutic drug doxorubicin hydrochloride (DOX) as a model drug was then loaded into the above MoS2@mSiO2 nanocarrier to prepare the tumor-targeting MoS2@mSiO2-DOX nanosystem. XRD, UV–Vis, FTIR, SEM, TEM, and DLS results jointly confirmed that the MoS2@mSiO2-DOX nanosystem with a particle size of approximately 370 nm was successfully synthesized. The XPS and BET analysis identified that the outer layer of MoS2@mSiO2 nanocarrier was SiO2, which has a large surface area of 99.41 m2/g with an average pore size of 3.5 nm coated on the MoS2. The in-vitro cytotoxicity and photothermal performance of the MoS2@mSiO2 nanodrug delivery system was tested, and the results show that MoS2@mSiO2 has a low toxicity to normal human liver cells (HL-7702), and which also exhibits a good photothermal stability with a photothermal conversion efficiency of 28.8%. With the aid of the large specific surface area of mSiO2 and the opposite zeta potential, a high amount of DOX was loaded on MoS2@mSiO2 nanocarrier, and the measured loading efficiency of DOX can reach up to 48.87%. The 48 h-drug release rate of MoS2@mSiO2-DOX reaches 35.65% under the conditions of near infrared (NIR) laser irradiation at pH=5.0, which is nearly 5 times higher than that of 6.26% under the normal physiological environment (pH=7.4 without NIR laser irradiation), indicating that the MoS2@mSiO2-DOX nanosystem possesses obvious pH and NIR laser responsive release characteristics. The MoS2@mSiO2 nanocarrier has good cytocompatibility, outstanding photothermal conversion and drug loading properties, and after DOX adsorption, the system exhibits excellent pH and laser responsive drug controlled release performance, which is expected to be widely used in the field of combining the photothermal-chemotherapy to synergistically resist tumor.

Copper‐Cysteine Nanostructures for Synergetic Photothermal Therapy and Chemodynamic Therapy of Bacterial Skin Abscesses

AbstractSkin lesions, including skin bacterial abscesses, have become one of the most important health challenges and usually need systemic high‐dose antibiotics. Therefore, it is of particular importance to develop novel approaches for treating this ever‐growing challenge to human health. To address this challenge, herein a copper nanostructure is developed giving combined photothermal and chemodynamic therapies for focal infection treatment. The Cu‐based nanostructures with intrinsic catalytic properties are prepared by D‐L or L cysteine (Cys) as ligand and copper ions. It is shown that the multifunctional copper‐Cys (Cu‐Cys) nanostructures can produce reactive oxygen species (ROS) and they exhibit near infrared (NIR)‐enhanced catalytic activities to improve ROS production for highly efficient eradication of bacteria. Moreover, the results proved O2 evolution property of the Cu‐Cys nanoparticles (NPs). The nanostructures show shape‐dependent antibacterial activity where DL‐Cu‐Cys NPs show higher bactericidal performance than L‐Cu‐Cys NPs. In vitro results demonstrate that 2.5 and 1.25 µg mL−1 of DL‐Cu‐Cys NPs is enough to achieve rapid killing of Escherichia coli (E. coli) or Staphylococcus aureus (S. aureus) respectively under 808 nm light irradiation in 10 min. This work introduces a unique photoactive nanoagent to efficiently treat subcutaneous abscess by combining NIR light‐triggered photothermal effect and catalytic generation of ROS without using any antibiotic.