Photothermal Response Research Articles

A review on human cancer and potential role of MXenes in cancer therapy

Cancer is the second leading cause of death worldwide and is having a serious impact on the global economy. Various treatment modalities are in use to treat cancer but none of the techniques is risk-free. Recently, various nanomaterials such as gold, boron, and other compounds have been investigated for radiotherapy and as anti-cancer drug carriers with promising results. MXenes are 2D novel nanomaterials and their biomedical and anticancer properties are gaining interest due to their high biomedical activity, less bio-toxicity, and photo-responsive nature. However, the biological properties of MXense have not been studied extensively, therefore, limited data is published on its in-vitro and in-vivo anticancer activities, drug loading efficacy, targeted release, and on its photothermal therapy response. In this review, we have discussed the use of nanoparticles and MXenen nanomaterial in cancer therapy. Furthermore, the role of Mxene as a photothermal agent and drug carrier has also been emphasized, along with the present challenges for the use of nanomaterials in the treatment of cancer.

Self-assembled hollow CuS@AuNRs/PDA nanohybrids with synergistically enhanced photothermal efficiency.

The design of multifunctional nanocarriers with enhanced photothermal efficiency is of great significance for the photothermal therapy of cancer. In this study, hollow CuS@gold nanorods/polydopamine (HCuS@AuNRs/PDA) nanohybrids with synergistically enhanced photothermal efficiency were prepared by electrostatic self-assembly method. The high photothermal conversion efficiency of HCuS@AuNRs (55.88%) is attributed to the interfacial electron transfer between CuS and AuNRs, as well as the increase in free charge carrier concentration. The excellent adhesion performance and strong negative charge of PDA ensure a high doxorubicin hydrochloride (DOX) loading efficiency of 96.08% for HCuS@AuNRs/PDA. In addition, HCuS@AuNRs/PDA reveals outstanding NIR/pH dual-responsive drug release properties owing to the weakened interaction between PDA and DOX in acidic media and the distinct NIR responsiveness of HCuS@AuNRs. In vitro cell viability results confirm that HCuS@AuNRs/PDA could efficiently kill tumor cells under the dual effect of acidic media and NIR laser. This study presents a novel nanocarrier with synergistically enhanced NIR photothermal responsiveness and high drug loading capacity, which provides a versatile platform in intelligent drug release and photothermal therapy.

Green Synthesis of Gold Nanoparticles by Celastrol for Chemotherapy and Photothermal Anticancer Therapy

The green synthesis of gold nanoparticles (Au NPs) using extracts or active ingredients from traditional Chinese medicine presents a novel approach characterized by simplicity, environmental friendliness, and independence from specific conditions. This innovative method combines the photothermal conversion properties of Au NPs with the chemotherapeutic effects of traditional Chinese medicine components, significantly enhancing anticancer efficacy. Celastrol (Cel), an effective medicinal ingredient extracted from the traditional Chinese herb Tripterygium wilfordii Hook. f. (TW), exhibits outstanding anticancer properties. In this study, Cel was successfully employed for the novel green synthesis of gold nanoparticles, forming Cel-Au NPs with a particle size of 50[Formula: see text]nm. Cel-Au NPs demonstrated excellent photothermal responsiveness, thermostability, and biocompatibility. The cytotoxicity of Cel-Au NPs on A549 cells reached approximately 80% upon exposure to 808[Formula: see text]nm near-infrared (NIR) irradiation. The anticancer activity was attributed to the induction of apoptosis and necrosis, achieved by elevating intracellular reactive oxygen species (ROS) levels and modulating the expression of apoptosis-related proteins. In conclusion, our synthesized Cel-Au NPs exhibited exceptional capabilities in chemotherapy and photothermal therapy, demonstrating excellent therapeutic efficacy and safety for cancer treatment.

Far-field, near-field and photothermal response of plasmonic twinned magnesium nanostructures.

Magnesium nanoparticles offer an alternative plasmonic platform capable of resonances across the ultraviolet, visible and near-infrared. Crystalline magnesium nanoparticles display twinning on the (101̄1), (101̄2), (101̄3), and (112̄1) planes leading to concave folded shapes named tents, chairs, tacos, and kites, respectively. We use the Wulff-based Crystal Creator tool to expand the range of Mg crystal shapes with twinning over the known Mg twin planes, i.e., (101̄x), x = 1, 2, 3 and (112̄y), y = 1, 2, 3, 4, and study the effects of relative facet expression on the resulting shapes. These shapes include both concave and convex structures, some of which have been experimentally observed. The resonant modes, far-field, and near-field optical responses of these unusual plasmonic shapes as well as their photothermal behaviour are reported, revealing the effects of folding angle and in-filling of the concave region. Significant differences exist between shapes, in particular regarding the maximum and average electric field enhancement. A maximum field enhancement (|E|/|E0|) of 184, comparable to that calculated for Au and Ag nanoparticles, was found at the tips of the (112̄4) kite. The presence of a 5 nm MgO shell is found to decrease the near-field enhancement by 67% to 90% depending on the shape, while it can increase the plasmon-induced temperature rise by up to 42%. Tip rounding on the otherwise sharp nanoparticle corners also significantly affects the maximum field enhancement. These results provide guidance for the design of enhancing and photothermal substrates for a variety of plasmonic applications across a wide spectral range.

Effect of slotting on the photothermal properties of silver nanopillars

Metal nanoparticles (MNPs) have attracted enormous research interest due to their excellent plasma properties. However, in the thermal utilization of solar energy, the narrowband absorption of MNPs limits their application. The investigation of MNP absorption through adjustment in the broadband spectrum holds significant scientific and practical implications. In this work, we study the effect of slotting on the light absorption and photothermal properties of silver nanopillars. The results show that the increase in the number of slots is beneficial to reduce scattering and improving the resonance absorption of silver nanopillar. Through the calculation of photothermal conversion efficiency, it is found that different slotting methods have different levels of improvement compared with silver nanopillars. The utilization of a combination of transverse and longitudinal slotting techniques leads to a 13 % enhancement in the photothermal conversion efficiency of silver nanopillars. The electric field distribution and temperature distribution at resonant wavelengths shows that the excellent light absorption ability of the slot nanopillars is caused by the “lightning rod” effect at the tip of the slit and the excitation of multiple plasmon resonances. The existence of slots is beneficial to compensate for the photothermal response of silver nanopillars in the near-infrared region. Our study proves that slotting helps enhance the application of silver nanopillars in solar thermal utilization.

Characterization of the Photothermal Response in Nanocomposite Silica Aerogel Materials with Thin Metal Films

The photothermal effect, whereby light energy is converted into thermal energy when absorbed in a material, is a phenomenon that has many potential applications including solar-driven water heating and purification, and radiative heat transfer. Recently, porous materials have been tailored to exhibit the photothermal effect to be used for interfacial water evaporation and sterilization. In this work we provide the characterization of the solar-driven photothermal effect on nanocomposite aerogel materials. Aerogels exhibit a unique combination of properties that can enhance their utility as a photothermal material. Due to their inherently low density and thermal conductivity, and their exceptional insulative properties, photothermal heat generated within an aerogel can remain trapped. This work presents the photothermal effect in nanocomposite aerogels fabricated by sputtering metal and metal oxide films onto and into aerogels materials. By sputtering metal and metal oxides in a high vacuum environment and directing it towards an aerogel substrate using a magnetron, we were able to deposit thin films onto the surface of an aerogel. The composite aerogels are characterized using scanning electron microscopy (SEM) to assess the depth of the sputtered material into the aerogel pores. The reflectance and transmittance of the aerogel composites are measured using UV-Vis spectroscopy. The photothermal effect in aerogel composites is measured using thermal imaging. Our results show that the photothermal response of the composite aerogels can be tuned by varying the thickness and composition of the deposited films. Overall, our study demonstrates the potential of using magnetron sputtering to create composite aerogels with tailored photothermal properties. This opens new opportunities for a wide range of applications such as water and air heating and purification, water desalination, and solar energy harvesting devices.

The influence of the reducing agent used during the synthesis of gelatin-coated gold nanorods on its thermal properties for photothermal application

The development of Gold nanorods (AuNRs) as phototherapeutic agents (PTAs) has attracted much interest from researchers in recent decades. The majority of their synthetic methods use Hydroquinone (HQ) and Ascorbic acid (AA) as the reducing agent, and these have been shown to affect the properties of AuNRs. However, no study has been conducted on how these two reducing reagents can affect their application, especially after coating. Therefore, we herein report a seed-mediated synthesis of AuNRs using two reducing agents and coating them with gelatin at different volume ratios (1:5, 1:2, 1:1,2:1, and 5:1). The HQ-reduced AuNRs and AA-reduced AuNRs absorbed at TSPR of 512 nm and 514 nm and LSPR of 914 nm and 847 nm, respectively. The gelatin-coated HQ-reduced and AA-reduced AuNRs did not show significant LSPR wavelength changes for all the volume ratios. However, a slight increase in the TSPR and the absorbance at regions below 550 nm was seen for volume ratios 1:1, 2:1, and 5:1. The thermal stability studies at 70 ℃ for the coated materials revealed that AA-reduced AuNRs were more thermally stable than HQ-reduced AuNRs, with the less optical shift. The coated AA-reduced AuNRs were further tested for photothermal responses. The results show that the high gelatin volume during coating affects the photothermal response of the AuNRs. This study indicates volume ratio of 1:5 and 1:2 has good stability while maintaining the good photothermal profiling needed in PTT applications. Hence Gel@AuNRs synthesised with AA is an excellent PTT agent for phototherapy applications.

Photoelectric-driven conductive composite ionogel patch for effective wound healing

Developing the high biosafety, effective and wearable devices for fast wound healing is highly desired but remains a challenge. Here, we propose a “win–win co-operation” strategy to potentiate effective skin wound healing at the wound site by constructing robust and ecofriendly composite patch under opto-electric stimulation. The wearable patch is composed of ionic gel doped with Ti3C2Tx (MXene), which possesses good photothermal response to kill the bacteria via effective inhibition of the expression of inflammatory factors, preventing wound infection. Importantly, the composite ionogel patch is capable of providing green and on-demand electrical stimulation for wound site, guiding cell migration and proliferation by improved bioenergy and expression up-regulation of growth factor. In mice wound models, the treatment group healed ∼31% more rapidly. Mechanistically, the wearable devices could enable visual and real-time supervising treatment effect due to their good transmittance. The proposed strategy would be promising for future clinical treatment of wound healing.

Hydrophobic Composite Foams with Asymmetric Gradient Sandwich Structure for Excellent Electromagnetic Interference Shielding and Photothermal Response.

The evolution of contemporary electronics urgently requires the use of versatile electromagnetic interference (EMI) shielding materials in complex environments. Interlayer polydimethylsiloxane (PDMS)/Fe3O4@multiwalled carbon nanotubes (MWCNTs) foams were prepared by a simple physical foaming method with excellent flexibility and electromagnetic wave absorption. The bottom nickel aramid paper (NiP) layer creates a dense conductive network by chemical plating technology, which ensures excellent EMI effectiveness. The upper carbon black (CB)/Fe3O4 layer further improves the absorption performance via conductive loss and magnetic loss. With the effective layout of the impedance matching layer, absorbing layer, and conductive shielding layer, the CB/Fe3O4-PDMS/Fe3O4@MWCNTs-NiP composite material achieves an EMI shielding effectiveness (EMI SE) of 61.7 dB and an absorption coefficient of 0.58 at X-band. In addition, the composite foam provides photothermal conversion and hydrophobicity due to the effective stacking of PDMS and CB/Fe3O4. Thus, the multifunctional composite foam presents a broad range of possible applications, benefiting EMI shielding as well as other specific areas.

Co‐delivery of Curcumin and Doxorubicin Using a pH‐photothermal Dual‐responsive and CD44‐targeted Nanocarrier for Enhanced Chemo‐photothermal Synergistic Tumor Treatment

AbstractIn this study, we have developed a novel approach for synergistic tumor treatment by utilizing degradable dendritic mesoporous silica nanoparticles loaded with doxorubicin and curcumin (Cur). These nanoparticles are equipped with polydopamine (PDA) for photothermal therapy and hyaluronic acid (HA) as a targeting ligand. The incorporation of PDA not only ensures the controlled release of therapeutic agents but also confers pH and photothermal responsiveness to the nanocarriers. Cur, a natural compound, serves as an antitumor sensitizer, elevating intracellular ROS levels to promote apoptosis. In addition, the excellent biocompatibility and targeting property of nanocarriers were enhanced by the HA‐modification, improving the effective accumulation in tumor cells. Comprehensive research including MTT assay, live/dead staining and ROS generation proved that the excellent antitumor capability of dual‐drug loaded nanocarriers was a result of chemo‐photothermal synergistic therapy and Cur‐induced cellular amplified ROS generation. The cellular uptake assays further demonstrated the efficiency of HA‐mediated intracellular accumulation, accelerated uptake driven by photothermal‐induced and a precise internalization pathway of nanocarriers. Furthermore, the results of in vivo biocompatibility revealed no significant blood and organ toxicity associated to the prepared nanocarriers. Our findings underscore the substantial potential of the proposed dual‐drug loaded nanocarriers for chemo‐photothermal synergistic therapy, offering a safe and promising strategy for effective tumor treatment.

Dual-signal amplification sensing platform based on competitive host-guest cycling recognition process for ultrasensitive detection of thyroglobulin

Dual-signal amplification sensing strategy has been constructed by the competitive host-guest cycling recognition process. Owing to superior photoelectric and photothermal performance of In2Se3 nanoparticles (NPs), the multifunctional probe modified with In2Se3 NPs can generate significantly increased photocurrent and temperature dual signals output during the one-time sensing process. To further achieve signal amplification, with the assistance of supramolecular host-guest recognition between β-cyclodextrin (β-CD) and adamantine (ADA), the energy band-matching TiO2 MOF was introduced to construct In2Se3/TiO2 heterojunction that enhance the separation efficiency of photogenerated electron-hole pairs. Interestingly, we found that quantum well-like interface structure (TiO2/In2Se3/TiO2) can be constructed through competitive host-guest cycling recognition process to continuously amplify the signals. The multiple heterostructures can significantly improve light absorption efficiency, not only effectively enhancing the anode photocurrent signal but also generating a robust photothermal response upon the excitation of near-infrared light irradiation. Based on this, the developed dual-signal amplification sensing platform realized ultrasensitive detection of target thyroglobulin (Tg) with linear range from 1.0 × 10−5 ng/mL to 1 ng/mL (R2 =0.98) and low detection limit 3.3 × 10−6 ng/mL. The strategy unprecedentedly couples In2Se3 NPs and TiO2 MOF to construct dual-signal amplification interfaces through competitive host-guest cycling recognition process, showing great promise for detection of the target biomarkers in clinical diagnosis.

A smartphone-assisted portable strategy based on maple leaf-like Au/Cu2S/MoS2 composite for photothermal and colorimetric sensing of cortisol

Herein, we describe a first-time synthesis of a maple leaf-like Au/Cu2S/MoS2 composite (denoted as ACM throughout this paper) with both photothermal and peroxidase (POD) activities. Based on the ACM, we developed a smartphone-assisted portable detection platform for the photothermal and colorimetric dual-mode sensing of cortisol in human saliva. Because of complementary base pairing, the “Y”-type signal-probe (formed by the coincubation of ACM-DNA1 and ACM-DNA2) is fixed on cortisol-specific aptamer-functionalized magnetic beads (MB–Aptcortisol). ​In the presence of target cortisol, MB-Aptcortisol is more likely to combine with cortisol, “Y”-type signal-probes are released, which can oxidize 3,3′,5,5′-tetramethylbenzidine (TMB) to blue oxTMB in the existence of H2O2. Notably, the oxTMB exhibits a distinct photothermal response which, in combination with the photothermal properties of the ACM, achieves transduction and signal amplification of cortisol through a cascade enzyme reaction. The photothermal and colorimetric signals increase with increasing target concentrations. This portable dual-signal sensing platform enables the detection of cortisol in the range of 5–10000 ng/mL, with detection limits of 0.11 and 0.25 ng/mL for photothermal and colorimetric signals, respectively (The reference concentration of cortisol in saliva of healthy people is 1–12 ng/mL in the morning and 0.1–3 ng/mL at night). It is inexpensive, user-friendly, and allows for rapid analysis, rendering it suitable for clinical applications.

Superhydrophobic multi-response actuator with high strength

Superhydrophobic actuators that are capable of moving on water surface under external stimuli has broad application prospects in various fields such as robots, environmental protection, sensors and freight transportation. However, the film actuators with soft materials as skeleton frames are easily deformed and destroyed when subjected to heavy loads, which severely restricts its further applications. Herein, we proposed a general and efficient strategy to fabricate a high-strength double-layer actuator composed of a metal/glass-based superhydrophobic substrate and a polymer superhydrophobic coating by combining the laser ablation and spraying techniques. The superhydrophobic coating not only possessed high adhesive strength with the ablated substrates, but also showed excellent self-cleaning, anti-ultraviolet irradiation and anti-stripping properties. Additionally, the addition of light and magnet response materials endowed the superhydrophobic coating with excellent photothermal and magnetic response properties, which supported the application of superhydrophobic actuators in different fields, such as freight collection and transportation.

Accessible Tetrathiafulvalene Moieties in a 3D Covalent Organic Framework for Enhanced Near-Infrared Photo-Thermal Conversion and Photo-Electrical Response.

Redox-active tetrathiafulvalene (TTF)-based covalent organic frameworks (COFs) exhibit distinctive electrochemical and photoelectrical properties, but their prevalent two-dimensional (2D) structure with densely packed TTF moieties limits the accessibility of redox center and constrains their potential applications. To overcome this challenge, an 8-connected TTF linker (TTF-8CHO) is designed as a new building block for the construction of three-dimensional (3D) COFs. This approach led to the successful synthesis of a 3D COF with the bcu topology, designated as TTF-8CHO-COF. In comparison to its 2D counterpart employing a 4-connected TTF linker, the 3D COF design enhances access to redox sites, facilitating controlled oxidation by I2 or Au3+ to tune physical properties. When irradiated with a 0.7Wcm-2 808nm laser, the oxidized 3D COF samples ( @TTF-8CHO-COF and Au NPs@TTF-8CHO-COF) demonstrated rapid temperature increases of 239.3 and 146.1°C, respectively, which surpassed those of pristine 3D COF (65.6°C) and the 2D COF counterpart (6.4°C increment after I2 treatment). Furthermore, the oxidation of the 3D COF heightened its photoelectrical responsiveness under 808nm laser irradiation. This augmentation in photothermal and photoelectrical response can be attributed to the higher concentration of TTF·+ radicals generated through the oxidation of well-exposed TTF moieties.

A Stable Open-Shell Conjugated Diradical Polymer with Ultra-High Photothermal Conversion Efficiency for NIR-II Photo-Immunotherapy of Metastatic Tumor

HighlightsBy employing side-chain regulation, the photothermal therapy response of conjugated diradical polymer can red-shift from near-infrared (NIR)-I to the NIR-II region. This strategy offers new radical materials in developing NIR-II photothermal materials.The conjugated diradical polymer TTB-2 receives a record-high photothermal conversion efficiency of 87.7%, far beyond the recently reported NIR-II photothermal agents. Such conjugated diradical polymer must enrich the NIR-II photothermal agents’ library and provide important insight for more diradical polymer construction.The conjugated diradical polymer nanoparticles TTB-2 NPs achieve good tumor photoablation with navigation of photoacoustic imaging in the NIR-II window, without any side effect. Furthermore, the efficient photo-immunity effect prevents the pulmonary metastasis of breast cancer.

Hybrid Aeromaterials for Enhanced and Rapid Volumetric Photothermal Response.

Conversion of light into heat is essential for a broad range of technologies such as solar thermal heating, catalysis and desalination. Three-dimensional (3D) carbon nanomaterial-based aerogels have been shown to hold great promise as photothermal transducer materials. However, until now, their light-to-heat conversion is limited by near-surface absorption, resulting in a strong heat localization only at the illuminated surface region, while most of the aerogel volume remains unused. We present a fabrication concept for highly porous (>99.9%) photothermal hybrid aeromaterials, which enable an ultrarapid and volumetric photothermal response with an enhancement by a factor of around 2.5 compared to the pristine variant. The hybrid aeromaterial is based on strongly light-scattering framework structures composed of interconnected hollow silicon dioxide (SiO2) microtubes, which are functionalized with extremely low amounts (in order of a few μg cm-3) of reduced graphene oxide (rGO) nanosheets, acting as photothermal agents. Tailoring the density of rGO within the framework structure enables us to control both light scattering and light absorption and thus the volumetric photothermal response. We further show that by rapid and repeatable gas activation, these transducer materials expand the field of photothermal applications, like untethered light-powered and light-controlled microfluidic pumps and soft pneumatic actuators.

Size-controlled synthesis and near-infrared photothermal response of Cp* Rh-based metalla[2]catenanes and rectangular metallamacrocycles

A variety of research reports on novel supramolecular topologies have been published over the last years. However, it is still a great challenge to tap into the inner functional properties of these complexes. Herein, two tetranuclear metallamacrocycles 1 and 2 and four octonuclear [2]catenanes 3–6 were constructed successfully via a coordination-driven self-assembly strategy, by conscious design and use of the tetramethyl bidentate pyridine ligand L1, and the appropriate selection of six binuclear half-sandwich rhodium building units with different longitudinal dimensions. The complexes have been fully characterized by single crystal X-ray diffraction analysis and NMR spectroscopy. Furthermore, near-infrared photothermal studies of the obtained [2]catenanes reveal different photothermal response in solid and solution states, which may be attributed to a strong fluorescence quenching effect of the half-sandwich organometallic fragment and different conjugated effect of Cp*Rh based building blocks in the interlocking structures. The photothermal conversion efficiencies of [2]catenanes 4–6 fall in the range 30.5%–16.5% respectively. This contribution aims to play a key role in the experimental development of Cp*-based photothermal materials.

Broadband Near-Infrared Photothermal Response of Tissue-Mimicking Phantoms Embedded with Plasmonic Gold Nanorod Aggregates: Implications for the Non-invasive Eradication of Malignant Tumors

Broadband Near-Infrared Photothermal Response of Tissue-Mimicking Phantoms Embedded with Plasmonic Gold Nanorod Aggregates: Implications for the Non-invasive Eradication of Malignant Tumors

In situ growth of MoS2@AuNRs nanoparticles with synergistically enhanced NIR response for controlled drug release

MoS2 nanosheets have received a lot of favor in biomedical applications due to their outstanding near-infrared (NIR) responsiveness. However, the poor aqueous dispersibility of MoS2 limits their biomedical application. In this paper, in-situ growth method was applied to integrate gold nanorods (AuNRs) with MoS2, and then MoS2 @AuNRs/HAP/PDA (denoted as MAHP) was prepared by introducing hydroxyapatite (HAP) and polydopamine (PDA) into MoS2 @AuNRs (MA) via self-assembly approach. In-situ grown MA inhibited the aggregation of MoS2 due to the insertion of AuNRs between MoS2 nanolayers. Therefore, MA revealed excellent aqueous dispersibility and synergistically enhanced NIR photothermal responsiveness (42.16% of photothermal conversion efficiency). In addition, MAHP exhibited outstanding DOX loading capacity (80%) and distinct pH-/NIR- dual responsive drug release properties, owing to the structural collapse of HAP in acidic medium and the excellent NIR responsiveness of MA. In vitro cell viability results revealed that MAHP could effectively kill MCF-7 cells under the dual effect of NIR laser irradiation and acidic medium. This paper presents a feasible process to prepare MoS2-based nanoparticles with NIR/pH dual-responsive release properties, which shows great potential in controlled photothermal therapy field.

Broad spectral response to photon energy unlimited by Schottky barrier from NiSi/Si junction

Recent advances in plasmonic absorption devices offer a novel approach for extending the range of silicon light detection. This is achieved by exploiting the Schottky interface energy barrier, which overcomes the limitation of the 1.12 eV photon energy conversion imposed by the silicon intrinsic bandgap. Internal photoemission has been widely accepted as the primary emission mechanism, which is mostly limited by the Schottky barrier height. However, we have discovered that carriers with energy lower than the Schottky barrier can generate electrical responses through the photothermal effect, breaking this restriction. In this study, we closely investigate two forms of photoresponses, namely photoelectric and photothermal, on a NiSi thin film Schottky photodetector, considering various factors such as temperature, applied bias, incident power, and wavelength regime. Without photothermal assistance, the device achieves a responsivity of 0.41 mA/W to a 1550 nm laser. Under bias-driven conditions, highly energized hot carriers generate a 2.18 μA photoelectric response, while a 0.861 μA photothermal response is simultaneously observed under 6 mW 1550 nm laser illumination. Through systematic investigation, we advance the mechanism of both responses by combining the hot carrier model and the Schottky barrier diagram. Finally, we experimentally obtain a 4.85 μA sheer photothermal response to a 0.475 mW 4-μm wavelength signal with 10.21 mA/W responsivity. It is expected that the device will also show responses to longer wavelengths.