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We present in this article an outline of some cyclotron-based irradiation techniques that can be used to directly radiolabel industrially manufactured nanoparticles, as well as two techniques for synthesis of labelled nanoparticles using cyclotron-generated radioactive precursor materials. These radiolabelled nanoparticles are suitable for a range of different in vitro and in vivo tracing studies of relevance to the field of nanotoxicology. A basic overview is given of the relevant physics of nuclear reactions regarding both ion-beam and neutron production of radioisotopes. The various issues that determine the practicality and usefulness of the different methods are discussed, including radioisotope yield, nuclear reaction kinetics, radiation and thermal damage, and radiolabel stability. Experimental details are presented regarding several techniques applied in our laboratories, including direct light-ion activation of dry nanoparticle samples, neutron activation of nanoparticles and suspensions using an ion-beam driven activator, spark-ignition generation of nanoparticle aerosols using activated electrode materials, and radiochemical synthesis of nanoparticles using cyclotron-produced isotopes. The application of these techniques is illustrated through short descriptions of some selected results thus far achieved. It is shown that these cyclotron-based methods offer a very useful range of options for nanoparticle radiolabelling despite some experimental difficulties associated with their application. For direct nanoparticle radiolabelling, if care is taken in choosing the experimental conditions applied, useful activity levels can be achieved in a wide range of nanoparticle types, without causing substantial thermal or radiation damage to the nanoparticle structure. Nanoparticle synthesis using radioactive precursors presents a different set of issues and offers a complementary and equally valid approach when laboratory generation of the nanoparticles is acceptable for the proposed studies, and where an appropriate radiolabel can be incorporated into the nanoparticles during synthesis.

The complex tumor microenvironment (TME) remains a major barrier to effective breast cancer therapy. A modular nanoplatform capable of sequentially reprogramming the TME through cascade actions and responsive therapeutic functions is developed to enhance breast cancer immunotherapy. A hybrid nanoparticle (MCC) containing manganese dioxide (MnO2), calcium peroxide (CaO2), and chlorin e6 (Ce6) is synthesized and subsequently camouflaged with a tumor cell membrane. Surface conjugation of a PD‐L1 antibody (αP) is then achieved via a glutathione (GSH)‐responsive fragment, resulting in the formation of an integrated nanoplatform MCC@TM‐αP. Through dual‐targeting mechanisms involving the tumor cell membrane and the PD‐L1 antibody, MCC@TM‐αP achieves efficient enrichment at tumor sites. MCC@TM‐αP alleviates hypoxia by generating O2 from CaO2 in the acidic TME and scavenges GSH via the MnO2‐mediated Fenton‐like reaction, thereby markedly amplifying the sonodynamic efficacy of Ce6. The combined effects of sonodynamic therapy and chemodynamic therapy ablate tumors and reprogram the immunosuppressive TME. Upon cleavage of the GSH‐responsive fragment by intratumoral GSH, MCC@TM‐αP releases the PD‐L1 antibody, eliciting a robust immune response that eradicates metastatic tumors. In murine breast cancer models, this therapeutic strategy enhances tumor infiltration by effector T cells and suppresses metastatic progression. By sequentially decoupling the immunosuppressive mechanisms, this study provides a programmable approach to potentiate immunotherapy and overcome TME‐driven resistance. A modular nanoplatform capable of sequentially reprogramming tumor microenvironment via cascade actions and responsive therapeutic functions is reported for breast cancer therapy. Via a dual‐targeting mechanism and responsive PD‐L1 antibody release, this nanoplatform enables amplified sonodynamic‐chemodynamic therapy and elicits robust immune response for eradicating metastatic tumors. This therapeutic tool demonstrates good antitumor and anti‐metastasis effects in murine breast cancer models.

Biocompatible gold nanoparticles designed to absorb light at wave-lengths of high tissue transparency have been of particular interest for biomedical applications. The ability of such nanoparticles to convert absorbed near-infrared light to heat and induce highly localized hyperthermia has been shown to be highly effective for photothermal cancer therapy, resulting in cell death and tumor remission in a multitude of preclinical animal models. Here we report the initial results of a clinical trial in which laser-excited gold-silica nanoshells (GSNs) were used in combination with magnetic resonance–ultrasound fusion imaging to focally ablate low-intermediate-grade tumors within the prostate. The overall goal is to provide highly localized regional control of prostate cancer that also results in greatly reduced patient morbidity and improved functional outcomes. This pilot device study reports feasibility and safety data from 16 cases of patients diagnosed with low- or intermediate-risk localized prostate cancer. After GSN infusion and high-precision laser ablation, patients underwent multiparametric MRI of the prostate at 48 to 72 h, followed by postprocedure mpMRI/ultrasound targeted fusion biopsies at 3 and 12 mo, as well as a standard 12-core systematic biopsy at 12 mo. GSN-mediated focal laser ablation was successfully achieved in 94% (15/16) of patients, with no significant difference in International Prostate Symptom Score or Sexual Health Inventory for Men observed after treatment. This treatment protocol appears to be feasible and safe in men with low- or intermediate-risk localized prostate cancer without serious complications or deleterious changes in genitourinary function.

Development of photothermal materials which are able to harness sunlight and convert it to thermal energy seems attractive. Besides carbon-based nanomaterials, conjugated polymers are emerging promising photothermal materials but their facile syntheses remain challenging. In this work, by modification of a CBT-Cys click condensation reaction and rational design of the starting materials, we facilely synthesize conjugated polymers poly-2-phenyl-benzobisthiazole (PPBBT) and its dihexyl derivative with good photothermal properties. Under the irradiation of either sunlight-mimicking Xe light or near-infrared laser, we verify that PPBBT has comparable photothermal heating-up speed to that of star material single-wall carbon nanotube. Moreover, PPBBT is used to fabricate water-soluble NP PPBBT nanoparticles which maintain excellent photothermal properties in vitro and photothermal therapy effect on the tumours exposed to laser irradiation. We envision that our synthetic method provides a facile approach to fabricate conjugated polymers for more promising applications in biomedicine or photovoltaics in the near future. Conjugated polymers are of interest for photothermal applications; however, synthesis of these polymers can be complex. Here, the authors report on a facile synthesis method that uses a modified CBT-Cys click reaction to make conjugated polymers and test these polymers for photothermal therapy applications.

Randomly adsorbing chemically synthesized silver nanocubes, each of which is the optical analogue of a grounded patch antenna, onto a nanoscale-thick polymer spacer layer on a gold film results in a metamaterial surface with a reflectance spectrum that can be tailored by varying the geometry. Nanocube antennas In many photonic applications ranging from sensors to energy-harvesting devices, a perfectly absorbing material is desired. Previously, perfect absorbers of infrared or visible light have been made by using lithography to create patterned structures on metallic surfaces, but this approach is expensive and difficult to scale up. Antoine Moreau et al . have developed an attractively simple method, in which silver nanocubes produced by wet chemistry are randomly distributed across a polymer-coated gold surface. Each cube acts as a nanoantenna to counter the reflectance of the metal surface. These cubes are simple and cheap to produce and can be easily spread and attached to the surface, so that large areas can be covered. They provide a means of controlling the colour of the reflected light, and the efficient optical response of the cubes suggests that mixed cube populations with controlled sized dispersion could be used to adjust the absorption at will. Efficient and tunable absorption is essential for a variety of applications, such as designing controlled-emissivity surfaces for thermophotovoltaic devices 1 , tailoring an infrared spectrum for controlled thermal dissipation 2 and producing detector elements for imaging 3 . Metamaterials based on metallic elements are particularly efficient as absorbing media, because both the electrical and the magnetic properties of a metamaterial can be tuned by structured design 4 . So far, metamaterial absorbers in the infrared or visible range have been fabricated using lithographically patterned metallic structures 2 , 5 , 6 , 7 , 8 , 9 , making them inherently difficult to produce over large areas and hence reducing their applicability. Here we demonstrate a simple method to create a metamaterial absorber by randomly adsorbing chemically synthesized silver nanocubes onto a nanoscale-thick polymer spacer layer on a gold film, making no effort to control the spatial arrangement of the cubes on the film. We show that the film-coupled nanocubes provide a reflectance spectrum that can be tailored by varying the geometry (the size of the cubes and/or the thickness of the spacer). Each nanocube is the optical analogue of a grounded patch antenna, with a nearly identical local field structure that is modified by the plasmonic response of the metal’s dielectric function, and with an anomalously large absorption efficiency that can be partly attributed to an interferometric effect 10 . The absorptivity of large surface areas can be controlled using this method, at scales out of reach of lithographic approaches (such as electron-beam lithography) that are otherwise required to manipulate matter on the nanoscale.

Light can exert radiation pressure on any object it encounters and that resulting optical force can be used to manipulate particles. It is commonly assumed that light should move a particle forward and indeed an incident plane wave with a photon momentum ħ k can only push any particle, independent of its properties, in the direction of k . Here we demonstrate, using full-wave simulations, that an anomalous lateral force can be induced in a direction perpendicular to that of the incident photon momentum if a chiral particle is placed above a substrate that does not break any left–right symmetry. Analytical theory shows that the lateral force emerges from the coupling between structural chirality (the handedness of the chiral particle) and the light reflected from the substrate surface. Such coupling induces a sideway force that pushes chiral particles with opposite handedness in opposite directions. Light carries momentum and therefore can be used to push small particles forward. Here, Wang and Chan demonstrate that under the right conditions a light beam can also exert sideway forces on chiral particles.

Dual-emissive systems showing color-specific photoswitching are promising in bioimaging and super-resolution microscopy. However, their switching efficiency has been limited because a delicate manipulation of all the energy transfer crosstalks in the systems is unfeasible. Here, we report a perfect color-specific photoswitching, which is rationally designed by combining the complete off-to-on fluorescence switching capability of a fluorescent photochromic diarylethene and the frustrated energy transfer to the other fluorescent dye based on the excited-state intramolecular proton transfer (ESIPT) process. Upon alternation of UV and visible light irradiations, the system achieves 100% switching on/off of blue emission from the diarylethene while orange emission from the ESIPT dye is unchanged in the polymer film. By fabricating this system into biocompatible polymer nanoparticles, we demonstrate microscopic imaging of RAW264.7 macrophage cells with reversible blue-color specific fluorescence switching that enables super-resolution imaging with a resolution of 70 nm. Photoswitchable nanoparticles can be used for selective imaging in biological systems but usually have only one color. Here the authors develop a two-color fluorescent emissive system that allows full on-off switching of one component color of the system while the other color is unaffected, which has implications for super-resolution imaging.

The development of sustainable methods for the degradation of pollutants in water is an ongoing critical challenge. Anthropogenic organic micropollutants such as pharmaceuticals, present in our water supplies in trace quantities, are currently not remediated by conventional treatment processes. Here, we report an initial demonstration of the oxidative degradation of organic micropollutants using specially designed nanoparticles and visible-wavelength sunlight. Gold “Janus” nanorods (Au JNRs), partially coated with silica to enhance their colloidal stability in aqueous solutions while also maintaining a partially uncoated Au surface to facilitate photocatalysis, were synthesized. Au JNRs were dispersed in an aqueous solution containing peroxydisulfate (PDS), where oxidative degradation of both simulant and actual organic micropollutants was observed. Photothermal heating, light-induced hot electron-driven charge transfer, and direct electron shuttling under dark conditions all contribute to the observed oxidation chemistry. This work not only provides an ideal platform for studying plasmonic photochemistry in aqueous medium but also opens the door for nanoengineered, solar-based methods to remediate recalcitrant micropollutants in water supplies.

The performance of magnetic nanoparticles is intimately entwined with their structure, mean size and magnetic anisotropy. Besides, ensembles offer a unique way of engineering the magnetic response by modifying the strength of the dipolar interactions between particles. Here we report on an experimental and theoretical analysis of magnetic hyperthermia, a rapidly developing technique in medical research and oncology. Experimentally, we demonstrate that single-domain cubic iron oxide particles resembling bacterial magnetosomes have superior magnetic heating efficiency compared to spherical particles of similar sizes. Monte Carlo simulations at the atomic level corroborate the larger anisotropy of the cubic particles in comparison with the spherical ones, thus evidencing the beneficial role of surface anisotropy in the improved heating power. Moreover we establish a quantitative link between the particle assembling, the interactions and the heating properties. This knowledge opens new perspectives for improved hyperthermia, an alternative to conventional cancer therapies.

Triplet-triplet annihilation upconversion nanoparticles have attracted considerable interest due to their promises in organic chemistry, solar energy harvesting and several biological applications. However, triplet-triplet annihilation upconversion in aqueous solutions is challenging due to sensitivity to oxygen, hindering its biological applications under ambient atmosphere. Herein, we report a simple enzymatic strategy to overcome oxygen-induced triplet-triplet annihilation upconversion quenching. This strategy stems from a glucose oxidase catalyzed glucose oxidation reaction, which enables rapid oxygen depletion to turn on upconversion in the aqueous solution. Furthermore, self-standing upconversion biological sensors of such nanoparticles are developed to detect glucose and measure the activity of enzymes related to glucose metabolism in a highly specific, sensitive and background-free manner. This study not only overcomes the key roadblock for applications of triplet-triplet annihilation upconversion nanoparticles in aqueous solutions, it also establishes the proof-of-concept to develop triplet-triplet annihilation upconversion nanoparticles as background free self-standing biological sensors. Triplet-triplet annihilation upconversion (TTA-UC) nanoparticles (NPs) are a promising material for diverse applications, but TTA-UC is sensitive to oxygen, which hinders its biological utility. Here, the authors report an enzymatic method to deplete oxygen and amplify the upconversion of TTA-UCNP in aqueous solution, and develop background-free glucose and glucose metabolism enzyme sensors.