Upconversion nanocomposite for programming combination cancer therapy by precise control of microscopic temperature

Ultralow-intensity near infrared light synchronously activated collaborative chemo/photothermal/photodynamic therapy

Although combined chemotherapy (Chemo), photothermal (PTT) and photodynamic (PDT) in cancer therapy has drawn significant attention due to its superior anticancer ability, the required high intensity of irradiation results in serious photo-toxicity to healthy neighboring cells, and thus limits its biomedical applications. Herein, we developed an ultralow-intensity near infrared (NIR) light synchronously activated collaborative Chemo/PTT/PDT nanoplatform. The nanoplatform is composed of a highly emissive upconversion (UC) core, chlorin e6 (Ce6) photosensitizer and the anticancer drug doxorubicin hydrochloride (DOX) co-loaded in a mesoporous silica (MS) shell, and polyethylene glycol-modified graphene (PGO) acts as both the photothermal reagent and smart switch for promoted drug release. Upon 808 nm NIR light exposure with ultralow intensity (0.25 W cm-2), which is below the maximum permissible exposure (MPE, 0.33 W cm-2) for skin, the mild hyperpyrexia of PGO induced both cancer cell irreversible death for PTT and greatly promoted drug release for enhanced Chemo. On the other hand, the upconverted 660 nm light from UC activated Ce6 to generate reactive oxygen species for PDT, while the upconverted 540 nm light from UC could be employed for visualizing the treatment process. The in vitro and in vivo anticancer experiments demonstrate that the ultralow-intensity NIR light synchronously activated Chemo/PTT/PDT nanoplatform exhibits remarkable therapeutic efficacy with minimal photodamage.

Peasecod-Like Hollow Upconversion Nanocrystals with Excellent Optical Thermometric Performance

Trivalent lanthanide (Ln3+)-doped hollow upconversion nanocrystals (UCNCs) usually exhibit unique optical performance that cannot be realized in their solid counterparts, and thus have been receiving tremendous interest from their fundamentals to diverse applications. However, all currently available Ln3+-doped UCNCs are solid in appearance, the preparation of hollow UCNCs remains nearly untouched hitherto. Herein, a class of UCNCs based on Yb3+/Er3+-doped tetralithium zirconium octafluoride (Li4ZrF8:Yb/Er) featuring 2D layered crystal lattice is reported, which makes the fabrication of hollow UCNCs with a peasecod-like shape possible after Ln3+ doping. By employing the first-principle calculations, the unique peasecod-like hollow nanoarchitecture primarily associated with the hetero-valence Yb3+/Er3+ doping into the 2D layered crystal lattice of Li4ZrF8 matrix is revealed. Benefiting from this hollow nanoarchitecture, the resulting Li4ZrF8:Yb/Er UCNCs exhibit an abnormal green upconversion luminescence in terms of the population ratio between two thermally coupled states (2H11/2 and 4S3/2) of Er3+ relative to their solid Li2ZrF6:Yb/Er counterparts, thereby allowing to prepare the first family of hollow Ln3+-doped UCNCs as supersensitive luminescent nanothermometer with almost the widest temperature sensing range (123-800 K). These findings described here unambiguously pave a new way to fabricate hollow Ln3+-doped UCNCs for numerous applications.

Single-wavelength phototheranostics for colon cancer via the thiolytic reaction

It's a huge challenge to develop effective nanosystems that combine the capabilities of diagnoses and therapies together for colon cancer in the clinic. Herein, we constructed a far-red absorbing phototheranostic nanosystem (FR-H2S) based on the thiolytic reaction of a dinitrophenyl modified phototheranostic prodrug and over-expressed H2S in colon cancer sites for precise imaging-guided phototherapy. FR-H2S with a BODIPY core not only could work as an imaging probe for diagnosis but also act as a phototherapeutic agent for cancer treatment under a single FR laser source (650 nm). FR-H2S exhibited a gradually enhanced fluorescence emission for precise diagnosis of H2S-rich colon tumor sites. After entering tumor cells, FR-H2S could generate abundant 1O2 and heat for phototherapies timely by using the same laser source (650 nm). We believe that this precise imaging-guided phototheranostic nanosystem could provide a promising approach to colon cancer with minimal damage.

Accurate and Real-Time Temperature Monitoring during MR Imaging Guided PTT

Photothermal therapy (PTT) is an efficient approach for cancer treatment. However, accurately monitoring the spatial distribution of photothermal transducing agents (PTAs) and mapping the real-time temperature change in tumor and peritumoral normal tissue remain a huge challenge. Here, we propose an innovative strategy to integrate T₁-MRI for precisely tracking PTAs with magnetic resonance temperature imaging (MRTI) for real-time monitoring temperature change in vivo during PTT. NaBiF₄: Gd@PDA@PEG nanomaterials were synthesized with favorable T₁-weighted performance to target tumor and localize PTAs. The extremely weak susceptibility (1.04 × 10^-6 emu g^-1 Oe^1-) of NaBiF₄: Gd@PDA@PEG interferes with the local phase marginally, which maintains the capability of MRTI to dynamically record real-time temperature change in tumor and peritumoral normal tissue. The time resolution is 19 s per frame, and the detection precision of temperature change is approximately 0.1 K. The approach achieving PTT guided by multimode MRI holds significant potential for the clinical application.

Reversible Thermochromic Nanoparticles Composed of a Eutectic Mixture for Temperature-Controlled Photothermal Therapy

Photothermal therapy (PTT) is an effective approach to cancer therapy. However, the high temperature during the therapy increases the damage to surrounding normal tissues. Thermochromic material, which exhibits temperature-activated color change and optical absorption, is a promising photothermal agent for precisely temperature-controlled PTT. Nevertheless, the construction of nanosized thermochromic particles with an appropriate transition temperature (44-47 °C) is still a great challenge. Here, thermochromic nanoparticles with the transition temperature at 45 °C based on a leuco dye-developer-solvent system are developed for thermostatic photothermal tumor therapy. Below the temperature, the nanoparticles take a dark green color to absorb light and convert it into heat efficiently. Once the temperature reaches the transition point, the colored nanoparticles switch to a colorless state, maintaining the temperature at the predefined level and allowing deeper light penetration. The autoregulated nanoparticles exhibit a prominent therapeutic effect for the tumor without destroying normal tissues.

A smart theranostic platform for photoacoustic and magnetic resonance dual-imaging-guided photothermal-enhanced chemodynamic therapy

The use of smart theranostic agents in multimodal imaging and treatment is a promising strategy to overcome the limitations of single mode diagnosis and treatment, and can greatly improve the diagnosis and effects of treatment. In this study, a gold@manganese dioxide (Au@MnO2) core-shell nanostructure was designed as a glutathione (GSH)-triggered smart theranostic agent for photoacoustic and magnetic resonance (MR) dual-imaging-guided photothermal-enhanced chemodynamic therapy. Both in vitro and in vivo experiments demonstrated not only that the photoacoustic and MR imaging function of Au@MnO2 could be activated by a high endogenous GSH concentration, but also that after being triggered by the endogenous GSH, Au@MnO2 had an excellent synergistic treatment effect in photothermal-enhanced chemodynamic therapy under the guidance of photoacoustic and MR imaging. This study demonstrated that the use of GSH-triggered Au@MnO2 in photoacoustic and MR dual-imaging-guided photothermal-enhanced chemodynamic therapy is a smart theranostic nanoplatform for the accurate diagnosis and efficient treatment of cancer.

Self-assembled CeVO4/Au heterojunction nanocrystals for photothermal/photoacoustic bimodal imaging-guided phototherapy

Phototherapy, including photothermal therapy (PTT) and photodynamic therapy (PDT), has attracted great attention because it can effectively inhibit the proliferation and propagation of cancer cells. Recently, heterojunction nanomaterials have shown tremendous application value in the field of biological medicine. In this work, the CeVO4/Au heterojunction nanocrystals (NCs) are designed for photothermal/photoacoustic bimodal imaging-guided phototherapy. The as-synthesized hydrophobic oleic acid (OA)-stabilized CeVO4 nanosheets were modified with HS-PEG-OH for translating into hydrophilic ones, which can significantly improve their stability and biocompatibility. Subsequently, the plasmonic Au nanoparticles were in situ successfully deposited on the surface of HS-PEG-coated CeVO4 to form CeVO4/Au heterojunction NCs for improving the visible and near-infrared light absorption, which results in enhanced photothermal conversion performance and reactive oxygen species (ROS) generation capacity. Thus, the CeVO4/Au can cause more severe damage to cancer cells than pure CeVO4 under NIR laser irradiation. Also, CeVO4/Au can provide distinct tumor contrast by photothermal/photoacoustic bimodal bioimaging. Our results demonstrate that CeVO4/Au NCs could be used as an effective theranostic anticancer agent for near-infrared (NIR) light-mediated PTT and PDT.

Ratiometric upconversion nanothermometry with dual emission at the same wavelength decoded via a time-resolved technique

The in vivo temperature monitoring of a microenvironment is significant in biology and nanomedicine research. Luminescent nanothermometry provides a noninvasive method of detecting the temperature in vivo with high sensitivity and high response speed. However, absorption and scattering in complex tissues limit the signal penetration depth and cause errors due to variation at different locations in vivo. In order to minimize these errors and monitor temperature in vivo, in the present work, we provided a strategy to fabricate a same-wavelength dual emission ratiometric upconversion luminescence nanothermometer based on a hybrid structure composed of upconversion emissive PbS quantum dots and Tm-doped upconversion nanoparticles. The ratiometric signal composed of two upconversion emissions working at the same wavelength, but different luminescent lifetimes, were decoded via a time-resolved technique. This nanothermometer improved the temperature monitoring ability and a thermal resolution and sensitivity of ~0.5 K and ~5.6% K⁻¹ were obtained in vivo, respectively.

Traditional ratiometric temperature monitoring is challenging due to the variation in tissue absorption and scattering of different wavelengths. Here, the authors show improved accuracy by using emission at the same wavelength, but different luminescent lifetimes decoded by a time-resolved technique.

Novel excited-state nanothermometry combining the red-shift of charge-transfer bands and a thermal coupling effect

Unprecedented excited-state nanothermometry with high sensitivity and low temperature uncertainty is proposed by combining the red-shift of V–O charge-transfer bands and a thermal coupling effect.

Strategies for Constructing Upconversion Luminescence Nanoprobes to Improve Signal Contrast

Lanthanide-doped upconversion nanoparticles (UCNPs) can convert two or more lower-energy near-infrared photons to a single photon with higher energy, which makes them particularly suitable for constructing nanoprobes with large imaging depth and minimal interference of autofluorescence and light scattering from biosamples. Furthermore, they feature excellent photostability, sharp and narrow emissions, and large anti-Stokes shift, which confer them the capability of long-period bioimaging and real-time tracking. In recent years, UCNPs-based nanoprobes (UC-nanoprobes) have been attracting increasing interest in biological and medical research. Signal contrast, the ratio of signal intensity after and before the reaction of the probe and target, is the determinant factor of the sensitivity of all reaction-based probes. This progress report presents the methods of constructing UC-nanoprobes, with a focus fixed on recent strategies to improve the signal contrast, which have kept on promoting the bioapplication of this type of probe.

Single-molecular phosphorus phthalocyanine-based near-infrared-II nanoagent for photothermal antitumor therapy

As one of the noninvasive cancer treatments, photothermal therapy (PTT) has drawn intense attention recently. In this context, an important task is to explore novel and versatile nanoscale photothermal agents (PTAs), especially those with strong NIR-II light absorption, high photothermal conversion efficiency, good photostability and biocompatibility. Phthalocyanines (Pcs), as the second-generation photosensitizers, are a promising class of candidates for PTT due to their strong NIR absorption and high photothermal conversion efficiency. However, the poor water solubility severely limited their application as PTAs in tumor treatment. Herein, we report a molecular phosphorus phthalocyanine (P-Pc)-based nanoagent via incorporation of human serum albumin (HSA) under mild conditions. The obtained nanoscale P-Pc-HSA possesses excellent photothermal conversion efficiency (64.7%) upon 1064 nm light irradiation, furthermore, it can be a highly efficient NIR-II antitumor nanoagent via photothermal treatment (PTT), which is fully evidenced by the in vitro and in vivo experiments.

A molecular phosphorus phthalocyanine (P-Pc)-based nanoagent P-Pc-HSA, which can be a highly efficient NIR-II antitumor agent, is reported.

Nanoscale Covalent Organic Framework for Combinatorial Antitumor Photodynamic and Photothermal Therapy

Despite the excellent photodynamic and photothermal properties of organic molecular photosensitizers (PSs) and photothermal agents (PTAs), such as porphyrin and naphthalocyanine, their poor water solubility severely impedes their biological applications. Covalent organic frameworks (COFs), as an emerging class of organic crystalline porous materials, possess free active end groups (bonding defects) and large inner pores, which make them an ideal type of nanocarriers for loading hydrophobic organic molecular PSs and PTAs by both bonding defect functionalization (BDF) and guest encapsulation approaches to obtain multifunctional nanomedicines for PDT/PTT combination therapy. In this work, we report a nanoscale COF (NCOF) prepared via a facile synthetic approach under ambient conditions. Furthermore, a dual-modal PDT/PTT therapeutic nanoagent, VONc@COF-Por (3), is successfully fabricated by stepwise BDF and guest encapsulation processes. The covalently grafted porphyrinic PS (Por) and the noncovalently loaded naphthalocyanine PTA (VONc) are independently responsible for the PDT and PTT functionalities of the nanoagent. Upon visible (red LED) and NIR (808 nm laser) irradiation, VONc@COF-Por (3) displayed high ¹O₂ generation and photothermal conversion ability (55.9%), consequently providing an excellent combined PDT/PTT therapeutic effect on inhibiting MCF-7 tumor cell proliferation and metastasis, which was well evidenced by in vitro and in vivo experiments. We believe that the results obtained herein can significantly promote the development of NCOF-based multifunctional nanomedicines for biomedical applications.

Simultaneous multi-signal quantification for highly precise serodiagnosis utilizing a rationally constructed platform

Serodiagnosis with a single quantification method suffers from high false positive/negative rates. In this study, a three-channel platform with an accessional instrumented system was constructed for simultaneous electrochemical, luminescent, and photothermal quantification of H₂S, a bio-indicator for acute pancreatitis (AP) diagnosis. Utilizing the specific reaction between platform and H₂S, the three-channel platform showed high sensitivity and selectivity in the biological H₂S concentration range. The three-channel platform was also feasible for identifying the difference in the plasma H₂S concentrations of AP and normal mice. More importantly, the precision of AP serodiagnosis was significantly improved (>99.0%) using the three-signal method based on the three-channel platform and an optimized threshold, which was clearly higher than that of the single- or two-signal methods (79.5%–94.1%). Our study highlights the importance of constructing a multichannel platform for the simultaneous multi-signal quantification of bio-indicators, and provides rigorous ways to improve the precision of medical serodiagnosis.

Single channel detection methods often suffer from false positives when analysing biological samples. Here, the authors report on the development of a three-channel detection device for measuring hydrogen sulphide in serum and demonstrate application in an in vivo model.

Upconversion System with Quantum Dots as Sensitizer: Improved Photoluminescence and PDT Efficiency

Upconversion nanoparticles (UCNPs) are prospective platforms for bioimaging and phototherapy, but a critical bottleneck is the limited brightness due to the faint absorptivity of lanthanide ions and the low quantum yield. To circumvent this problem, we herein propose our strategy to reconstruct the energy cascade of UCNPs using semiconductor quantum dots (QDs) as light sensitizer of Nd³⁺/Yb³⁺ codoped UCNPs. Ag₂Se QDs with strong absorption at 808 nm acted as efficient antenna and transferred their energy to Yb³⁺ via a resonance energy transfer process, significantly enhancing the luminescence of UCNPs. This nanocomposite was then combined with Rose Bengal and applied for photodynamic therapy. Both in vitro and in vivo studies revealed the introduction of QDs improved the therapeutic performance remarkably. Our study suggests Ag₂Se QDs with excellent photophysical properties can be promising agents to overcome the shortcomings of UCNPs and further strengthen their applications.

Recent Progress of Rare-Earth Doped Upconversion Nanoparticles: Synthesis, Optimization, and Applications

Upconversion is a nonlinear optical phenomenon that involves the emission of high-energy photons by sequential absorption of two or more low-energy excitation photons. Due to their excellent physiochemical properties such as deep penetration depth, little damage to samples, and high chemical stability, upconversion nanoparticles (UCNPs) are extensively applied in bioimaging, biosensing, theranostic, and photochemical reactions. Here, recent achievements in the synthesis, optimization, and applications of UCNP-based nanomaterials are reviewed. The state-of-the-art approaches to synthesize UCNPs in the past few years are introduced first, followed by a summary of several strategies to optimize upconversion emissive properties and various applications of UCNPs. Lastly, the challenges and future perspectives of UCNPs are provided as a conclusion.

Prediction of Thermal-Coupled Thermometric Performance of Er3

Predicting the thermometric performance of diverse materials will facilitate the selection and design of nanothermometers to suit complex environments and specific signal outputs while saving much time and expense. Herein we explore and unveil the thermal-coupled thermometric performance of Er³⁺/Yb³⁺ codoped in a set of host lattices via the chemical bond theory of complex crystals. The unknown B and ΔE values of the thermometry are accurately estimated by the chemical bond parameters, further deepening our cognition of the correlation between the luminescence properties of Er³⁺ ions and the microscopic crystal structure. This allows us to precisely forecast the thermal-coupled thermometric performance of Er³⁺ for varying host lattices in advance.

Anisotropic Excitation Polarization Response from a Single White Light-Emitting β-NaYF4 :Yb3+ ,Pr3+ Microcrystal

Precise knowledge about optical and structural performance of individual rare earth (RE)-doped particles is extremely important for the optimization of luminescent particles and for fully exploiting their capability as multifunctional probes for interdisciplinary applications. In this work, optical and structural anisotropy of individual particles through RE-doped single fluoride microcrystals with controllable morphology is reported. Unique luminescent phenomena, for example, white light-emission from Pr³⁺ at single particle level and different photoluminescent spectra variation dependence on excitation polarization orientation at different excitation direction are observed upon excitation with a 980 nm linearly polarized laser. Based on the analysis of local site symmetry and electron cloud distribution of REs in hexagonal structure by density functional theory calculations, an exciting mechanism of excitation polarization response anisotropy is given for the first time, providing a guidance for emission polarization simultaneously. The structural anisotropy is presented in Raman spectra with obvious differing Raman curves, revealing the reason why there are differences between powder groups. Taking advantage of anisotropic crystals, potential applications in microscopic multi-information transportation are suggested for the optical and structural performance anisotropy from RE-doped fluoride single nano/microcrystals to ordered nano/microcrystal arrays, such as local rate probing in a flowing liquid.

A highly active (102) surface-induced rapid degradation of a CuS nanotheranostic platform for in situ T1-weighted magnetic resonance imaging-guided synergistic therapy

Polyvinylpyrrolidone-modified CuS nanocrystals (CuS NCs) with high photothermal conversion efficiency (46%) and pH and near-infrared (NIR) light-triggered degradation properties are a promising nanotheranostic platform for in situ magnetic resonance imaging (MRI)-guided synergistic photothermal and photodynamic therapy. On the one hand, the (102) surface of CuS NCs has a small bandgap based on density functional theory, which leads to high photothermal conversion efficiency. On the other hand, the S vacancy formation energy of the (102) surface is favourable. On entry into tumor cells through endocytosis, the S^2- ions on the (102) surface of CuS NCs can be easily oxidized under the tumor microenvironment and 808 nm laser irradiation; then, a large amount of Cu⁺ ions can be released from CuS NCs and accelerate the degradation of nanocrystals. Cu⁺ ions can generate reactive oxygen species (ROS) under the tumor microenvironment and 808 nm laser irradiation. Meanwhile, the oxidation product Cu²⁺ ions can be generated from the oxidized Cu⁺ ions and applied for in situ T₁-weighted magnetic resonance imaging. Moreover, the biodegradable CuS NCs possess a high tumor uptake and can be rapidly excreted with a low long-term retention/toxicity. Therefore, degradable and multifunctional CuS NCs are a safe and efficient candidate for the diagnosis and treatment of cancer.

Au Hollow Nanorods-Chimeric Peptide Nanocarrier for NIR-II Photothermal Therapy and Real-time Apoptosis Imaging for Tumor Theranostics

The strategy that combines photodynamic therapy (PDT) and photothermal therapy (PTT) is widely used to achieve strong antitumor efficiency. Since light in the NIR-II window possesses ideal penetration ability, developing NIR-II PTT and NIR-II light triggered photosensitizer release for combined PDT and PTT is very promising in nanomedicine.

Methods: We develop a novel nanocarrier (termed AuHNRs-DTPP) by conjugating photosensitizer contained chimeric peptide (DTPP) to Au hollow nanorods (AuHNRs). AuHNRs was obtained by a Te-templated method with the assistance of L-cysteine. The chimeric peptide PpIX-PEG8-GGK(TPP)GRDEVDGC (DTPP) was obtained through a solid-phase peptide synthesis (SPPS) method.

Results: Under the 1064 nm laser irradiation, the nanocarrier can accumulate heat quickly for efficient PTT, and then release activated photosensitizer for real-time apoptosis imaging. Thereafter, supplementary PDT can be conducted to kill tumor cells survived from the PTT, and meanwhile the normal tissue can be protected from photo-toxicity.

Conclusion: This designed AuHNRs-DTPP nanocarrier with remarkable therapy effect, real-time apoptosis imaging ability and reduced skin damage is of great potential in nanomedicine application.

Effects of BCc1 nanoparticle and its mixture with doxorubicin on survival of murine 4T1 tumor model

Background: Our previous findings showed that BCc1, a nanoparticle designed based on nanochelating technology, can be considered a new anti-cancer nanoparticle if confirmed by complementary studies.

Goal: In the present study, we investigated the effects of the BCc1 nanoparticle alone on some gene expressions influencing the apoptosis pathway, and also the effect of the mixture of BCc1 nanoparticle and doxorubicin on survival.

Method: Using an in vitro study, the effects of the BCc1 nanoparticle on Bax, Bcl2, p53, Caspase7 and p21 gene expressions were assessed after a 24-h treatment using real-time PCR in MCF-7 and MEFs; in addition, using an in vivo study, 4T1 tumor-bearing female Balb/c mice were treated with different doses of the BCc1 nanoparticle and doxorubicin alone and together and then their mean and median survival was evaluated.

Result: The results showed that the BCc1 nanoparticle increased gene expressions of RB, p53, Caspase7, p21, and Bax and decreased gene expressions of Bcl2 in MCF-7 significantly, but no change was observed in MEFs expressions. The findings revealed that the BCc1 nanoparticle, when used orally, had the highest mean and median survival time. A mixture of a high dose of the BCc1 nanoparticle (1 mg/kg) and a low dose of doxorubicin (0.1 mg/kg) showed synergistic effects on enhanced life span, while doxorubicin dose was prescribed approximately 50 times less than the murine applicable dose (5 mg/kg).

Conclusion: Our results demonstrated that the BCc1 nanoparticle not only has the potential to become a novel nanomedicine for cancer therapy, but it can also provide the basis of a new medicine for cancer management when mixed with a lower applicable dose of doxorubicin.

PEGylated rhenium nanoclusters: a degradable metal photothermal nanoagent for cancer therapy

A common issue of functional nanoagents for potential clinical translation is whether they are biodegradable or renal clearable. Previous studies have widely explored noble metal nanoparticles (Au and Pd) as the first generation of photothermal nanoagents for cancer therapy, but all of the reported noble metal nanoparticles are non-degradable. On the other hand, rhenium (Re), one of the noble and precious metals with a high atomic number (Z = 75), has been mainly utilized as a jet superalloy or chemical catalyst, but the biological characteristics and activity of Re nanoparticles have never been evaluated until now. To address these issues, here we report a simple and scalable liquid-reduction strategy to synthesize PEGylated Re nanoclusters, which exhibit intrinsically high photothermal conversion efficacy (33.0%) and high X-ray attenuation (21.2 HU mL mg-1), resulting in excellent photothermal ablation (100% tumor elimination) and higher CT enhancement (15.9 HU mL mg-1 for commercial iopromide in clinics). Impressively, biocompatible Re nanoclusters can degrade into renal clearable ReO4 - ions after exposure to H2O2, and thus achieve much higher renal clearance efficiency than conventional gold nanoparticles. This work reveals the potential of theranostic application of metallic Re nanoclusters with both biodegradation and renal clearance properties and provides insights into the design of degradable metallic platforms with high clinical prospects.

On-Demand Detaching Nanosystem for the Spatiotemporal Control of Cancer Theranostics

Engineering multiple theranostic modalities into a single nanoscale entity holds great potential to rejuvenate cancer treatments; however, enabling the sophisticated spatiotemporal control of each component for maximizing theranostic improvement and minimizing side effects concurrently remains a challenge. Herein, an intelligent detachable "nanorocket" is developed to sequentially manipulate and optimize multitheranostic processes for magnetic resonance-assisted ultrasound-drug combined therapy (MR-HIFU-Drug). The "nanorocket" is constructed by integrating multicomponent (MnCO₃, doxorubicin, silica) on the pH-sensitive CaCO₃ nanoparticles step by step via cation exchange and controlled heterogeneous nucleation, in which doxorubicin is encapsulated in both carbonates and silica component. The "nanorocket" can initiate sequential detachment in the acidic tumor microenvironment. Specifically, carbonates decompose instantly, releasing Mn²⁺ as the MR contrast agent and leaving hollow silica nanostructure behind as the HIFU synergistic agent. Consequently, burst release of drug is also triggered, further triggering the degradation of silica, which in turn regulates the slow release of drug from the silica matrix. Thus, efficient tumor inhibition is achieved by enhanced HIFU ablation and biphase release of doxorubicin with a stepwise clearance of Mn and Si. This work establishes a system for the systematic spatiotemporal dispatch of diverse theranostic components for the balance of efficacy and safety in cancer theranostics.

Noninvasive temperature monitoring for dual-modal tumor therapy based on lanthanide-doped up-conversion nanocomposites

Accurate treatment of photothermal therapy (PTT) is crucial to avoid the unnecessary injury of normal cells and tissues. Therefore the real-time temperature monitoring in the PTT process has drawn more and more attention in recent years. Herein, we designed and prepared one kind of lanthanide (Ln3+)-doped up-conversion nanocomposites with multi-functions, which can not only provide temperature feedback in PTT process, but also play the photodynamic therapy (PDT) function for the synergistic effect of tumor therapy. Based on NaYF4:Yb, Er up-conversion nanoparticles (UCNPs), mesoporous SiO2 was modified on the surface combined with photosensitizer Chlorin e6 (Ce6) molecules, which could be excited by red emission of Er3+ under the 980 nm laser. Cit-CuS NPs were further linked on the surface of the composite served as photothermal conversion agent, therefore, the temperature of the PTT site can be monitored by recording the ratio of I525/I545 of green emissions, especially within the physiological range. Based on the guidance obtained from spectral experiments, we further investigated the dual-modal therapy effect both in vitro and in vivo, respectively, and acquired decent results.

Upconversion-mediated ZnFe2O4 nanoplatform for NIR-enhanced chemodynamic and photodynamic therapy

ZnFe2O4, a semiconductor catalyst with high photocatalytic activity, is ultrasensitive to ultraviolet (UV) light and tumor H2O2 for producing reactive oxygen species (ROS). Thereby, ZnFe2O4 can be used for photodynamic therapy (PDT) from direct electron transfer and the newly defined chemodynamic therapy (CDT) from the Fenton reaction. However, UV light has confined applicability because of its high phototoxicity, low penetration, and speedy attenuation in the biotissue. Herein, an upconversion-mediated nanoplatform with a mesoporous ZnFe2O4 shell was developed for near-infrared (NIR) light enhanced CDT and PDT. The nanoplatform (denoted as Y-UCSZ) was comprised of upconversion nanoparticles (UCNPs), silica shell, and mesoporous ZnFe2O4 shell and was synthesized through a facile hydrothermal method. The UCNPs can efficiently transfer penetrable NIR photons to UV light, which can activate ZnFe2O4 for producing singlet oxygen thus promoting the Fenton reaction for ROS generation. Besides, Y-UCSZ possesses enormous internal space, which is highly beneficial for housing DOX (doxorubicin, a chemotherapeutic agent) to realize chemotherapy. Moreover, the T 2-weighted magnetic resonance imaging (MRI) effect from Fe3+ and Gd3+ ions in combination with the inherent upconversion luminescence (UCL) imaging and computed tomography (CT) from the UCNPs makes an all-in-one diagnosis and treatment system. Importantly, in vitro and in vivo assays authenticated excellent biocompatibility of the PEGylated Y-UCSZ (PEG/Y-UCSZ) and high anticancer effectiveness of the DOX loaded PEG/Y-UCSZ (PEG/Y-UCSZ&DOX), indicating its potential application in the cancer treatment field.

In Situ Synthesis of Fluorescent Mesoporous Silica-Carbon Dot Nanohybrids Featuring Folate Receptor-Overexpressing Cancer Cell Targeting and Drug Delivery

Multifunctional nanocarrier-based theranostics is supposed to overcome some key problems in cancer treatment. In this work, a novel method for the preparation of a fluorescent mesoporous silica-carbon dot nanohybrid was developed. Carbon dots (CDs), from folic acid as the raw material, were prepared in situ and anchored on the surface of amino-modified mesoporous silica nanoparticles (MSNs-NH₂) via a microwave-assisted solvothermal reaction. The as-prepared nanohybrid (designated MSNs-CDs) not only exhibited strong and stable yellow emission but also preserved the unique features of MSNs (e.g., mesoporous structure, large specific surface area, and good biocompatibility), demonstrating a potential capability for fluorescence imaging-guided drug delivery. More interestingly, the MSNs-CDs nanohybrid was able to selectively target folate receptor-overexpressing cancer cells (e.g., HeLa), indicating that folic acid still retained its function even after undergoing the solvothermal reaction. Benefited by these excellent properties, the fluorescent MSNs-CDs nanohybrid can be employed as a fluorescence-guided nanocarrier for the targeted delivery of anticancer drugs (e.g., doxorubicin), thereby enhancing chemotherapeutic efficacy and reducing side effects. Our studies may provide a facile strategy for the fabrication of multifunctional MSN-based theranostic platforms, which is beneficial in the diagnosis and therapy of cancers in future.

Ce6-Modified Carbon Dots for Multimodal-Imaging-Guided and Single-NIR-Laser-Triggered Photothermal/Photodynamic Synergistic Cancer Therapy by Reduced Irradiation Power

Photomediated cancer therapy, mainly including photothermal (PT) therapy (PTT) and photodynamic therapy (PDT), has attracted tremendous attention in recent years thanks to its noninvasive and stimuli-responsive features. The single mode of PTT or PDT, however, has obvious drawbacks, either requiring high-power laser irradiation to generate enough heat or only providing limited efficacy due to the hypoxia nature inside tumors. In addition, the reported synergistic PTT/PDT generally utilized two excitation sources to separately activate PTT and PDT, and the problem of high-power laser irradiation for PTT was still not well solved. Herein, a new concept, loading a small amount of photosensitizers onto a PTT agent (both of them can be triggered by a single-near-infrared (NIR) laser), was proposed to evade the shortcomings of PTT and PDT. To validate this idea, minute quantities of photosensitizer chlorin e6 (Ce6) (0.56% of mass) were anchored onto amino-rich red emissive carbon dots (RCDs) that possess superior photothermal (PT) character under 671 nm NIR laser (PT conversion efficiency to be 46%), and meanwhile the PDT of Ce6 can be activated by this laser irradiation as well. The findings demonstrate that Ce6-modified RCDs (named Ce6-RCDs) offer much higher cancer therapy efficacy under a reduced laser power density (i.e., 0.50 W cm^-2 at 671 nm) in vitro and in vivo than the equivalent RCDs or Ce6 under the same irradiation conditions. Besides, the Ce6-RCDs also exhibit multimodal imaging capabilities (i.e., fluorescence (FL), photoacoustic (PA), and PT), which can be employed for guidance of the phototherapy process. This study suggests not only a strategy to enhance cancer phototherapy efficacy but also a promising candidate (i.e., Ce6-RCDs) for multimodal FL/PA/PT imaging-guided and single-NIR-laser-triggered synergistic PTT/PDT for cancers by a reduced irradiation power.

Probing Energy Migration through Precise Control of Interfacial Energy Transfer in Nanostructure

A novel mechanistic strategy for probing the energy migration through constructing the interfacial energy transfer (IET) in a core-shell-shell nanostructure is reported. In this design, the trilayer nanostructure is composed of a sensitizing core, a migratory interlayer, and a detective shell layer that interact with each other only by IET and the latter two shell layers are nonresponsive to the incident irradiation. This model is well applied in investigating the energy migration over the Tb, Gd, and Yb sublattices, and the results show that the Gd sublattice holds the best energy migratory performance. Moreover, the finding of energy migration over the Yb sublattice enables the 808 nm excited long-lived upconversion of Tb³⁺ and Eu³⁺ , which exhibits unique time-gating performance for information security. The results provide a facile and powerful nanosized model for an in-depth understanding of the fundamentals involving lanthanide interactions, which will further help excite new chances for the frontier applications of lanthanide-based luminescent materials.

Rare Earth Hydroxide as a Precursor for Controlled Fabrication of Uniform β-NaYF₄ Nanoparticles: A Novel, Low Cost, and Facile Method

In recent years, rare earth doped upconversion nanocrystals have been widely used in different fields owing to their unique merits. Although rare earth chlorides and trifluoroacetates are commonly used precursors for the synthesis of nanocrystals, they have certain disadvantages. For example, rare earth chlorides are expensive and rare earth trifluoroacetates produce toxic gases during the reaction. To overcome these drawbacks, we use the less expensive rare earth hydroxide as a precursor to synthesize β-NaYF₄ nanoparticles with multiform shapes and sizes. Small-sized nanocrystals (15 nm) can be obtained by precisely controlling the synthesis conditions. Compared with the previous methods, the current method is more facile and has lower cost. In addition, the defects of the nanocrystal surface are reduced through constructing core–shell structures, resulting in enhanced upconversion luminescence intensity.

A smart tumor microenvironment responsive nanoplatform based on upconversion nanoparticles for efficient multimodal imaging guided therapy

A smart tumor microenvironment responsive theranostic nanoplatform USPDF for UCL/CT dual-mode imaging and combination of chemotherapy and photothermal therapy.

Critical Considerations on the Clinical Translation of Upconversion Nanoparticles (UCNPs): Recommendations from the European Upconversion Network (COST Action CM1403)

The unique photoluminescent properties of upconversion nanoparticles (UCNPs) have attracted worldwide research interest and inspired many bioanalytical applications. The anti-Stokes emission with long luminescence lifetimes, narrow and multiple absorption and emission bands, and excellent photostability enable background-free and multiplexed detection in deep tissues. So far, however, in vitro and in vivo applications of UCNPs are restricted to the laboratory use due to safety concerns. Possible harmful effects may originate from the chemical composition but also from the small size of UCNPs. Potential end users must rely on well-founded safety data. Thus, a risk to benefit assessment of the envisioned combined therapeutic and diagnostic ("theranostic") applications is fundamentally important to bridge the translational gap between laboratory and clinics. The COST Action CM1403 "The European Upconversion Network-From the Design of Photon-Upconverting Nanomaterials to Biomedical Applications" integrates research on UCNPs ranging from fundamental materials synthesis and research, detection instrumentation, biofunctionalization, and bioassay development to toxicity testing. Such an interdisciplinary approach is necessary for a better and safer theranostic use of UCNPs. Here, the status of nanotoxicity research on UCNPs is compared to other nanomaterials, and routes for the translation of UCNPs into clinical applications are delineated.

Magnetic Regulation of Thermo-Chemotherapy from a Cucurbit[7]uril-Crosslinked Hybrid Hydrogel

The fabrication, characterization, and therapy efficiency of a noncovalent-bonded hydrogel network, which is assembled by utilizing cucurbit[7]uril as a supramolecular linker to "stick" superparamagnetic γ-Fe₂ O₃ nanoparticles onto the polymer backbone of catechol-functionalized chitosan are described. The unique barrel-shaped structure of cucurbit[7]uril not only facilitates host-guest recognition with the catechol derivatives, but also forms robust electrostatic interactions between its carbonyl portals and the γ-Fe₂ O₃ nanoparticles in a supramolecular manner, which leaves the physical and chemical properties of the nanoparticles intact. The γ-Fe₂ O₃ nanoparticles display vibrational movement and heat generation under an alternating magnetic field, endowing the formed hybrid supramolecular hydrogel with both thermo- and chemotherapy modalities, which are demonstrated both in vitro and in vivo. Here, a facile strategy is introduced to construct noncovalent interactions between a polymer matrix and the incorporated nanoparticles, which is amendable to a wide range of biomedical and industrial applications.

Tunable color emission based on the activator shell thickness of multilayer core–shell nanoparticles under double NIR excitation

Rare earth luminescent nanomaterials are hot topic due to their unique fluorescence properties. Effective spectral regulation could be achieved by adjusting the coating thickness to affect the energy transfer process in core–shell structure.

Paving Metal-Organic Frameworks with Upconversion Nanoparticles via Self-Assembly

The combination of metal-organic frameworks (MOFs) and luminescent nanomaterials with upconversion characteristics could enable the development of new nanomaterials and applications in information security, optical sensing, and theranostics. However, currently available methods are not ideally suitable for fabricating composites of MOF and upconversion nanomaterial, and incorporating upconversion nanomaterials with MOFs in a controllable manner remains challenging. Here, we demonstrate an in situ self-assembly route to the nanocomposites in which MOFs are homogeneously paved with upconversion nanoparticles. Without additional assistance, this strategy, mainly driven by electrostatic interactions, can be used to incorporate different upconversion nanoparticles with diverse MOFs. The as-synthesized composites can be further used to construct composites with unique structures, such as MOF@upconversion nanoparticles@MOF sandwiched nanocomposites, and would be useful for applications including luminescence-monitored drug delivery, anticounterfeiting, and photodynamic therapy. These findings should shed light on new avenues for fabricating multifunctional composites of MOF and upconversion nanomaterials for varied applications.