Star-Shaped Magnetic-Plasmonic Au@Fe3O4 Nano-Heterostructures for Photothermal Therapy

Development of iron oxide based-upconversion nanocomposites for cancer therapeutics treatment

Administration of therapeutic strategies alongside magnetic multifunctional nanocomposites has displayed improved cancer prognosis. However, the clinical use of this combination is limited owing to poor bioimaging performance, low biocompatibility, restricted tissue penetration in ultraviolet/visible regions, and low therapeutic efficacy of nanocomposites. To overcome these existing challenges, we designed iron oxide (Fe3O4)-based upconversion nanoparticles (UCNPs). Fe3O4 nanoparticles were synthesized via facile solvothermal method and incorporated into mesoporous silica (mS) layer (Fe3O4@mS). Fe3O4@mS nanoparticles were further decorated onto the surface of the UCNPs as a core material (UCNP-Fe3O4@mS, FMUP). Methotrexate (MTX) an efficient anticancer drug was loaded onto the mesoporous silica to produce FMUP-MTX nanocomposite. The FMUP nanocomposite displayed excellent photothermal therapy and showed 43% photothermal conversion efficiency. The designed nanocomposite has ability to decompose H2O2 to generates hydroxyl radical that promote chemodynamic therapy effect due to attribution of Fenton reaction. FMUP-MTX nanocomposite possessed improved chemotherapeutic performance under NIR laser irradiation. Further, T2-weighted magnetic resonance imaging performance of nanocomposite was observed. In vitro studies shown that cell viability was decreased to 25% under laser irradiation due to the therapeutic effect. In vivo studies exhibited that the FMUP-MTX nanocomposite inhibited the tumor growth with the laser irradiation. Therefore, these nanocomposites can be considered as a promising candidate for cancer therapeutics treatment.

Plasmonic nanoarchitectured systems for biomedical application

In this paper we discuss the latest developments in colloidal plasmonics, a field with over a century of history, applied to the biomedical sector. Emphasis is placed on the nanoarchitectonic nature of plasmonic systems that can be used for sensing, drug delivery and manipulation of biomolecules. For instance, quantum effects linked to plasmonic phenomena are being used to enhance monitoring of chiral particles and their interaction with light, which is essential for the pharmaceutical industry in reaching the required enantiopurity in some drugs. In diagnostics, radiofrequency waves can excite surface plasmon resonance through amplified photoacoustic effects, thus permitting thermo-acoustic imaging. An example of enhanced therapy was introduced in carefully designed nanoarchitectures where a multi-branched gold nanooctopus was surrounded by a mesoporous polydopamine and loaded with ribonucleoproteins for the target delivery into tumor cells. Moreover, the longstanding challenge of heating due to Ohmic losses, which has hindered the use of plasmonic tweezers for manipulating biologically relevant analytes, is now being exploited for enhanced trapping, manipulation, and transport of cells and other biological particles. The combination of magnetic materials and plasmonic colloids in the realms of magnetoplasmonics can also be explored in sensing and enhanced drug delivery, which further exemplifies the versatility of nanoarchitectonics.

Temperature and light dual-responsive hydrogels for anti-inflammation and wound repair monitoring

Wound healing is a complex and dynamic biological process that requires meticulous management to ensure optimal outcomes. Traditional wound dressings, such as gauze and bandages, although commonly used, often fall short in their frequent need for replacement, lack of real-time monitoring and absence of anti-inflammatory and antibacterial properties, which can lead to increased risk of infection and delayed healing. Here, we address these limitations by introducing an innovative hydrogel dressing, named PHDNN6, to combine wireless Bluetooth temperature monitoring and light-triggered nitric oxide (NO) release to enhance wound healing and management. The PHDNN6 hydrogel is based on a poly(N-isopropylacrylamide) (PNIPAM) matrix, integrated with methacrylated and dopamine-grafted hyaluronic acid (HA-MA-DA), which allows the dressing to be highly responsive to changes in wound temperature, enabling continuous and real-time monitoring of the wound microenvironment wirelessly. Besides, PHDNN6 is embedded with photothermal polydopamine nanoparticles (PDA NPs) that are loaded with a NO donor, N,N'-di-sec-butyl-N,N'-dinitroso-1,4-phenylenediamine (BNN6). When exposed to near-infrared (NIR) laser irradiation, these PDA@BNN6 nanoparticles release NO to provide potent antibacterial and anti-inflammatory effects. The integration of continuous wireless temperature monitoring with NO release within a single hydrogel dressing represents a significant advancement in clinical wound care. This dual-functional platform not only provides real-time diagnostic capabilities but also offers therapeutic interventions to manage wound infections and promote tissue regeneration. Our research highlights the potential of PHDNN6 to revolutionize wound management by offering a comprehensive solution that addresses both the diagnostic and therapeutic needs in wound healing.

Magnetic-Plasmonic Core-Shell Nanoparticles: Properties, Synthesis and Applications for Cancer Detection and Treatment

Nanoparticles have been widely used in cancer diagnostics and treatment research due to their unique properties. Magnetic nanoparticles are popular in imaging techniques due to their ability to alter the magnetization field around them. Plasmonic nanoparticles are mainly applied in cancer treatments like photothermal therapy due to their ability to convert light into heat. While these nanoparticles are popular among their respective fields, magnetic-plasmonic core-shell nanoparticles (MPNPs) have gained popularity in recent years due to the combined magnetic and optical properties from the core and shell. MPNPs have stood out in cancer theranostics as a multimodal platform capable of serving as a contrast agent for imaging, a guidable drug carrier, and causing cellular ablation through photothermal energy conversion. In this review, we summarize the different properties of MPNPs and the most common synthesis approaches. We particularly discuss applications of MPNPs in cancer diagnosis and treatment based on different mechanisms using the magnetic and optical properties of the particles. Lastly, we look into current challenges they face for clinical applications and future perspectives using MPNPs for cancer detection and therapy.

Magnetic field-induced synergistic therapy of cancer using magnetoplasmonic nanoplatform

Combining photothermal and chemotherapy using single nanoplatform is an emerging direction in cancer nanomedicine. Herein, a magnetic field (MF) induced combination of chemo/photothermal therapy is demonstrated using Fe3O4@mSiO2@Au core@shell@satellites nanoparticles (NPs) loaded with chemotherapeutic drug doxorubicin (DOX), both in vitro and in vivo. An application of an external MF to the NPs dispersion causes magnetophoretic movement and aggregation of the NPs. While the synthesized NPs only slightly absorb light at ∼800 nm, their aggregation results in a significant near infrared (NIR) absorption associated with plasmon resonance coupling between the Au satellites in the NPs aggregates. As a result, the aggregates revealed an enhanced photothermal conversion efficiency (∼67 % versus ∼19 % for NPs in absence of MF) and an enhanced NIR photothermal effect was observed under 808 nm laser irradiation. A combination of the MF induced NIR photothermal therapy (PTT) with DOX chemotherapeutic action resulted in an efficient killing of NPs treated cancer cells in vitro and tumor growth restriction in 4T1-tumor-bearing mice in vivo. Histological studies showed striking differences in development and malignancy between tumors treated with the combination of NPs, MF and an 808 nm laser, and the control treatments, revealing a synergy of the MF-induced NIR PTT and chemotherapy and suggesting a promising strategy for cancer therapy.

Combination Using Magnetic Iron Oxide Nanoparticles and Magnetic Field for Cancer Therapy

Iron oxide nanoparticles (MNPs) demonstrate notable benefits in magnetic induction, attributed to their distinctive physical and chemical attributes. Emerging cancer treatment utilizing magnetic fields have also gathered increasing attention in the biomedical field. However, the defects of difficult dispersion and poor biocompatibility of MNPs seriously hinder their application. In order to overcome its inherent defects and maximize the therapeutic potential of MNPs, various functionalized MNPs have been developed, and numerous combined treatment methods based on MNPs have been widely studied. In this review, we compare and analyze the common nanoparticles based on MNPs with different sizes, shapes, and functional modifications. Additionally, we introduced the therapeutic mechanisms of the strategies, such as magnetically controlled targeting, magnetic hyperthermia, and magneto-mechanical effect, which based on the unique magnetic induction capabilities of MNPs. Finally, main challenges of MNPs as smart nanomaterials were also discussed. This review seeks to offer a thorough overview of MNPs in biomedicine and a new sight for their application in tumor treatment.

Recent advancements and clinical aspects of engineered iron oxide nanoplatforms for magnetic hyperthermia-induced cancer therapy

The pervasiveness of cancer is a global health concern posing a major threat in terms of mortality and incidence rates. Magnetic hyperthermia (MHT) employing biocompatible magnetic nanoparticles (MNPs) ensuring selective attachment to target sites, better colloidal stability and conserving nearby healthy tissues has garnered widespread acceptance as a promising clinical treatment for cancer cell death. In this direction, multifunctional iron oxide nanoparticles (IONPs) are of significant interest for improved cancer care due to finite size effect associated with inherent magnetic properties. This review offers a comprehensive perception of IONPs-mediated MHT from fundamentals to clinical translation, by elucidating the underlying mechanism of heat generation and the related influential factors. Biological mechanisms underlying MHT-mediated cancer cell death such as reactive oxygen species generation and lysosomal membrane permeabilization have been discussed in this review. Recent advances in biological interactions (in vitro and in vivo) of IONPs and their translation to clinical MHT applications are briefed. New frontiers and prospects of promising combination cancer therapies such as MHT with photothermal therapy, cancer starvation therapy and sonodynamic therapy are presented in detail. Finally, this review concludes by addressing current crucial challenges and proposing possible solutions to achieve clinical success.

First Cu-nanostar as a sustainable catalyst realized through synergistic effects of bowl-shaped features and surface activation of sporopollenin exine

Recently, nanostar-shaped structures, including gold nanostars (NS), have drawn much attention for their potential use in surface-enhanced Raman spectroscopy (SERS) and catalysis. Yet, very few studies have been conducted on Cu-Au hybrid NS, and there are none for Cu-based NS. Herein, we describe an effective method for controlling copper-oxide nanostar (ESP-PEI-CuI/IIO-NS) growth using sporopollenin as a sustainable template material. However, ESP-PEI-CuI/IIO-NS growth depends on sporopollenin surface functionalization. Sporopollenin surface activation was done by amine functionalization with polyethyleneimine (PEI), without which ESP-PEI-CuI/IIO-NS growth was not observed. The sporopollenin's exine (outer wall) has a bowl-like structure, which mediates the growth of Cu nanorods, resulting in an NS morphology. Furthermore, due to their increased surface area, ESP-PEI-CuI/IIO-NS showed excellent catalytic activity for Huisgen 1,3-dipolar cycloadditions even when used in H2O and without additives under green conditions. This approach utilising biomass as a sustainable template would pave the way for developing controlled growth of nanostructures for SERS-related and catalytic applications.

Iron Oxide Nanoparticles: Parameters for Optimized Photoconversion Efficiency in Synergistic Cancer Treatment

Photothermal therapy (PTT) can overcome cancer treatment resistance by enhancing the cell membrane permeability, facilitating drug accumulation, and promoting drug release within the tumor tissue. Iron oxide nanoparticles (IONPs) have emerged as effective agents for PTT due to their unique properties and biocompatibility. Approved for the treatment of anemia, as MRI contrast agents, and as magnetic hyperthermia mediators, IONPs also offer excellent light-to-heat conversion and can be manipulated using external magnetic fields for targeted accumulation in specific tissue. Optimizing parameters such as the laser wavelength, power density, shape, size, iron oxidation state, functionalization, and concentration is crucial for IONPs' effectiveness. In addition to PTT, IONPs enhance other cancer treatment modalities. They improve tumor oxygenation, enhancing the efficacy of radiotherapy and photodynamic therapy. IONPs can also trigger ferroptosis, a programmed cell death pathway mediated by iron-dependent lipid peroxidation. Their magneto-mechanical effect allows them to exert a mechanical force on cancer cells to destroy tumors, minimizing the damage to healthy tissue. This review outlines strategies for the management of the photothermal performance and PTT efficiency with iron oxide nanoparticles, as well as synergies with other cancer therapies.

Enhancing MRI through high loading of superparamagnetic nanogels with high sensitivity to the tumor environment

Tumors pose a significant threat to human health, and their occurrence and fatality rates are on the rise each year. Accurate tumor diagnosis is crucial in preventing untimely treatment and late-stage metastasis, thereby reducing mortality. To address this, we have developed a novel type of hybrid nanogel called γ-Fe2O3@PNIPAM/PAm/CTS, which contains iron oxide nanoparticles and poly(N-isopropyl acrylamide)/polyacrylamide/chitosan. The rationale for this study relies on the concept that thermosensitive PNIPAM has the ability to contract when exposed to elevated temperature conditions found within tumors. This contraction leads to a dense clustering of the high-loading γ-Fe2O3 nanoparticles within the nanogel, thus greatly enhancing the capabilities of MRI. Additionally, the amino groups in chitosan on the particle surface can be converted into ammonium salts under mildly acidic conditions, allowing for an increase in the charge of the nanogel specifically at the slightly acidic tumor site. Consequently, it promotes the phagocytosis of tumor cells and effectively enhances the accumulation and retention of nanogels at the tumor site. The synthesis of the hybrid nanogels involves a surfactant-free emulsion copolymerization process, where vinyl-modified γ-Fe2O3 superparamagnetic nanoparticles are copolymerized with the monomers in the presence of chitosan. We have optimized various reaction parameters to achieve a high loading content of the superparamagnetic nanoparticles, reaching up to 60%. The achieved r 2 value of 517.74 mM-1 S-1 significantly surpasses that of the clinical imaging contrast agent Resovist (approximately 151 mM-1 S-1). To assess the performance of these magnetic nanogels, we conducted experiments using Cal27 oral tumors and 4T1 breast tumors in animal models. The nanogels exhibited temperature- and pH-sensitivity, enabling magnetic targeting and enhancing diagnosis through MRI. The results demonstrated the potential of these hybrid nanogels as contrast agents for magnetic targeting in biomedical applications.

Magnetic-Plasmonic Nanocomposites as Versatile Substrates for Surface-enhanced Raman Scattering (SERS) Spectroscopy

Surface-enhanced Raman scattering (SERS) spectroscopy, a highly sensitive technique for detecting trace-level analytes, relies on plasmonic substrates. The choice of substrate, its morphology, and the excitation wavelength are crucial in SERS applications. To address advanced SERS requirements, the design and use of efficient nanocomposite substrates have become increasingly important. Notably, magnetic-plasmonic (MP) nanocomposites, which combine magnetic and plasmonic properties within a single particle system, stand out as promising nanoarchitectures with versatile applications in nanomedicine and SERS spectroscopy. In this review, we present an overview of MP nanocomposite fabrication methods, explore surface functionalization strategies, and evaluate their use in SERS. Our focus is on how different nanocomposite designs, magnetic and plasmonic properties, and surface modifications can significantly influence their SERS-related characteristics, thereby affecting their performance in specific applications such as separation, environmental monitoring, and biological applications. Reviewing recent studies highlights the multifaceted nature of these materials, which have great potential to transform SERS applications across a range of fields, from medical diagnostics to environmental monitoring. Finally, we discuss the prospects of MP nanocomposites, anticipating favorable developments that will make substantial contributions to various scientific and technological areas.

Biological Applications of Thermoplasmonics

Thermoplasmonics has emerged as an extraordinarily versatile tool with profound applications across various biological domains ranging from medical science to cell biology and biophysics. The key feature of nanoscale plasmonic heating involves remote activation of heating by applying laser irradiation to plasmonic nanostructures that are designed to optimally convert light into heat. This unique capability paves the way for a diverse array of applications, facilitating the exploration of critical biological processes such as cell differentiation, repair, signaling, and protein functionality, and the advancement of biosensing techniques. Of particular significance is the rapid heat cycling that can be achieved through thermoplasmonics, which has ushered in remarkable technical innovations such as accelerated amplification of DNA through quantitative reverse transcription polymerase chain reaction. Finally, medical applications of photothermal therapy have recently completed clinical trials with remarkable results in prostate cancer, which will inevitably lead to the implementation of photothermal therapy for a number of diseases in the future. Within this review, we offer a survey of the latest advancements in the burgeoning field of thermoplasmonics, with a keen emphasis on its transformative applications within the realm of biosciences.

A hydrogel gripper enabling fine movement based on spatiotemporal mineralization

Fine tailoring of the subtle movements of a hydrogel actuator through simple methods has widespread application prospects in wearable electronics, bionic robots and biomedical engineering. However, to the best of our knowledge, this challenge is not yet completed. Inspired by the diffusion-reaction process in nature, a hydrogel gripper with the capability of fine movement was successfully prepared based on the spatiotemporal fabrication of the polypyrrole (PPY) pattern in a poly (N-isopropylacrylamide) (PNIPAM) hydrogel. The hydrogel was given gradient porous structures using a one-step UV irradiation method. Moreover, photothermal PPY patterns on the hydrogel were obtained through spatiotemporal mineralization of ferric hydroxide followed by the polymerization of pyrrole in a controllable manner. Taking advantage of the unique structures, the hydrogel gripper can not only achieve reversible grasping-releasing of substrates with the tuning of temperature (similar to that of hands), but also generate delicate movement under the irradiation of light (resembling that of finger joints). The strategy reported here is easily accessible and there is no need for sophisticated templates, therefore making it superior to other existing methods. We believe this work will provide references for the design and application of more advanced soft actuators.

Biocompatible Snowman-like Dimer Nanoparticles for Improved Cellular Uptake in Intrahepatic Cholangiocarcinoma

Intrahepatic cholangiocarcinoma (ICC) is one of the most aggressive types of human cancers. Although paclitaxel (PTX) was proven to exert potent anti-tumor effects against ICC, the delivery of PTX is still challenging due to its hydrophobic property. Nanoparticle (NP)-based carriers have been proven to be effective drug delivery vehicles. Among their physicochemical properties, the shape of NPs plays a crucial role in their performance of cellular internalization and thus anti-tumor efficacy of loaded drugs. In this study, dumbbell-like and snowman-like dimer NPs, composed of a polylactic acid (PLA) bulb and a shellac bulb, were designed and prepared as drug nanocarriers to enhance the efficiency of cellular uptake and anti-tumor performance. PLA/shellac dimer NPs prepared through rapid solvent exchange and controlled co-precipitation are biocompatible and their shape could flexibly be tuned by adjusting the concentration ratio of shellac to PLA. Drug-loaded snowman-like PLA/shellac dimer NPs with a sharp shape exhibit the highest cellular uptake and best cell-killing ability against cancer cells in an in vitro ICC model over traditional spherical NPs and dumbbell-like dimer NPs, as proven with the measurements of flow cytometry, fluorescent confocal microscopy, and the CCK8 assay. The underlying mechanism may be attributed to the lower surface energy required for the smaller bulbs of snowman-like PLA/shellac dimer NPs to make the initial contact with the cell membrane, which facilitates the subsequent penetration through the cellular membrane. Therefore, these dimer NPs provide a versatile platform to tune the shape of NPs and develop innovative drug nanocarriers that hold great promise to enhance cellular uptake and therapeutic efficacy.

Revealing the Effect of Photothermal Therapy on Human Breast Cancer Cells: A Combined Study from Mechanical Properties to Membrane HSP70

Hyperthermia-induced overexpression of heat shock protein 70 (HSP70) leads to the thermoresistance of cancer cells and reduces the efficiency of photothermal therapy (PTT). In contrast, cancer cell-specific membrane-associated HSP70 has been proven to activate antitumor immune responses. The dual effect of HSP70 on cancer cells inspires us that in-depth research of membrane HSP70 (mHSP70) during PTT treatment is essential. In this work, a PTT treatment platform for human breast cancer cells (MCF-7 cells) based on a mPEG-NH₂-modified polydopamine (PDA)-coated gold nanorod core-shell structure (GNR@PDA-PEG) is developed. Using the force-distance curve-based atomic force microscopy (FD-based AFM), we gain insight into the PTT-induced changes in the morphology, mechanical properties, and mHSP70 expression and distribution of individual MCF-7 cells with high-resolution at the single-cell level. PTT treatment causes pseudopod contraction of MCF-7 cells and generates a high level of intracellular reactive oxygen species, which severely disrupt the cytoskeleton, leading to a decrease in cellular mechanical properties. The adhesion maps, which are recorded by aptamer A8 functional probes using FD-based AFM, reveal that PTT treatment causes a significant upregulation of mHSP70 expression and it starts to exhibit a partial aggregation distribution on the MCF-7 cell surface. This work not only exemplifies that AFM can be a powerful tool for detecting changes in cancer cells during PTT treatment but also provides a better view for targeting mHSP70 for cancer therapy.

Quantitative Analysis of Photothermal Therapy of Tumor Tissue Using Various Gold Nanoparticle Injection Schemes

Photothermal therapy is a new chemotherapy technique using photothermal effects, a phenomenon in which light energy is converted into thermal energy. Since the treatment technique is performed without surgical incision, it does not cause bleeding and patients are expected to make rapid recoveries, which are significant advantages. In this study, photothermal therapy with direct injection of gold nanoparticles into tumor tissue was simulated through numerical modeling. The treatment effect resulting from changing the intensity of the irradiated laser, volume fraction of the injected gold nanoparticles, and number of gold nanoparticle injections was quantitatively evaluated. The discrete dipole approximation method was applied to calculate the optical properties of the entire medium, and the Monte Carlo method was applied to identify the absorption and scattering behavior of lasers in tissue. In addition, by confirming the temperature distribution of the entire medium through the calculated light absorption distribution, the treatment effect of photothermal therapy was evaluated, and the optimal treatment conditions were suggested. This is expected to accelerate the popularization of photothermal therapy in the future.

Recent advances in magnetic nanocarriers for tumor treatment

Magnetic nanocarriers are nano-platforms that integrate multiple moieties based on magnetic nanoparticles for diagnostic and therapeutic purposes. In recent years, they have become an advanced platform for tumor treatment due to their wide application in magnetic resonance imaging (MRI), biocatalysis, magneto-thermal therapy (MHT), and photoresponsive therapy. Drugs loaded into magnetic nanocarriers can efficiently be directed to targeted areas by precisely reshaping their structural properties. Magnetic nanocarriers allow us to track the location of the therapeutic agent, continuously control the therapeutic process and eventually assess the efficacy of the treatment. They are typically used in synergistic therapeutic applications to achieve precise and effective tumor treatment. Here we review their latest applications in tumor treatment, including stimuli-responsive drug delivery, MHT, photoresponsive therapy, immunotherapy, gene therapy, and synergistic therapy. We consider reducing toxicity, improving antitumor efficacy, and the targeting accuracy of magnetic nanocarriers. The challenges of their clinical translation and prospects in cancer therapy are also discussed.

Bifunctional Magnetite–Gold Nanoparticles for Magneto-Mechanical Actuation and Cancer Cell Destruction

Magnetite–gold dumbbell nanoparticles are essential for biomedical applications due to the presence of two surfaces with different chemical natures and the potential combination of magnetic and plasmonic properties. Here, the remote actuation of Fe3O4-Au hybrid particles in a rotating (1 Hz, 7 mT), static (7 mT) or pulsed low-frequency (31 Hz, 175 mT, 30 s pulse/30 s pause) magnetic field was studied. The particles were synthesized by a high-temperature wet chemistry protocol and exhibited superparamagnetic properties with the saturation magnetization of 67.9 ± 3.0 Am2 kg−1. We showcased the nanoparticles’ controlled aggregation in chains (rotating/static magnetic field) in an aqueous solution and their disaggregation when the field was removed. The investigation of nanoparticle uptake by LNCaP and PC-3 cancer cells demonstrated that Fe3O4-Au hybrids mainly escaped endosomes and accumulated in the cytoplasm. A significant fraction of them still responded to a rotating magnetic field, forming short chains. The particles were not toxic to cells at concentrations up to 210 μg (Fe3O4) mL−1. However, cell viability decrease after incubation with the nanoparticles (≥70 μg mL−1) and exposure to a pulsed low-frequency magnetic field was found. We ascribe this effect to mechanically induced cell destruction. Overall, this makes Fe3O4-Au nanostructures promising candidates for intracellular actuation for future magneto-mechanical cancer therapies.

Smart Nanostructured Materials for SARS-CoV-2 and Variants Prevention, Biosensing and Vaccination

The coronavirus disease 2019 (COVID-19) pandemic, caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has raised great concerns about human health globally. At the current stage, prevention and vaccination are still the most efficient ways to slow down the pandemic and to treat SARS-CoV-2 in various aspects. In this review, we summarize current progress and research activities in developing smart nanostructured materials for COVID-19 prevention, sensing, and vaccination. A few established concepts to prevent the spreading of SARS-CoV-2 and the variants of concerns (VOCs) are firstly reviewed, which emphasizes the importance of smart nanostructures in cutting the virus spreading chains. In the second part, we focus our discussion on the development of stimuli-responsive nanostructures for high-performance biosensing and detection of SARS-CoV-2 and VOCs. The use of nanostructures in developing effective and reliable vaccines for SARS-CoV-2 and VOCs will be introduced in the following section. In the conclusion, we summarize the current research focus on smart nanostructured materials for SARS-CoV-2 treatment. Some existing challenges are also provided, which need continuous efforts in creating smart nanostructured materials for coronavirus biosensing, treatment, and vaccination.

Invisible Thermoplasmonic Indium Tin Oxide Nanoparticle Ink for Anti-counterfeiting Applications

In this study, we present a thermoplasmonic transparent ink based on a colloidal dispersion of indium tin oxide (ITO) nanoparticles, which can offer several advantages as anti-counterfeiting technology. The custom ink could be directly printed on several substrates, and it is transparent under visible light but is able to generate heat by absorption of NIR radiation. Dynamic temperature mapping of the printed motifs was performed by using a thermal camera while irradiating the samples with an IR lamp. The printed samples presented fine features (in the order of 75 μm) and high thermal resolution (of about 250 μm). The findings are supported by thermal finite-element simulations, which also allow us to explore the effect of different substrate characteristics on the thermal readout. Finally, we built a demonstrator comprising a QR Code invisible to the naked eye, which became visible in thermal images under NIR radiation. The high transparency of the printed ink and the high speed of the thermal reading (figures appear/disappear in less than 1 s) offer an extremely promising strategy toward low-cost, scalable production of photothermally active invisible labels.