Rationally designed upconversion nanoprobe for simultaneous highly sensitive ratiometric detection of fluoride ions and fluorosis theranostics

Multichannel Lanthanide-Doped Nanoprobes for Serodiagnosis and Therapy

In this account, we will highlight recent progress in the development of multichannel lanthanide-doped (MC-Ln) nanoprobes for highly efficient serodiagnosis and therapy, with a particular focus on our own work. First, we first provide a classification of the types of MC-Ln nanoprobes based on the contained type and number of signals. The merits of different types of nanoprobes and the reason using lanthanides are elucidated. Then, we provide an overview of the current uses of MC-Ln nanoprobes in serodiagnosis and therapy, focusing on the strategic exploration to improve the diagnostic and therapeutic performance from different perspectives. Finally, we present a prospective outlook on the future development and potential issues of next-generation MC-Ln nanoprobes. We hope that this timely account will update our understanding of MC-Ln and similar nanoprobes for bioapplications and provide helpful references for the state-of-the-art tools for serodiagnosis and therapy.

A New Phenothiazine-Based Fluorescent Probe for Rapid and Specific Detection of Fluoride

Fluorescent probes with specific and rapid response to fluoride ions are important mediators for detecting fluoride ions in biological systems. In this study, a phenothiazine-based fluorescent probe, PTC, was designed and synthesized, which undergoes cleavage activation and cyclization induced by fluoride ions targeting Si-O bonds. The probe exhibits strong anti-interference properties and reaches peak fluorescence within 5 min, allowing for quantitative detection of fluoride ions content in the concentration range of 0 to 12.5μM, suitable for live cell fluorescence imaging. The research findings suggest its potential application value in biological systems.

Self-ratiometric fluorescent platform based on upconversion nanoparticles for on-site detection of chlorpyrifos

Monitoring organophosphorus pesticides is significant for food safety assessment. Herein, we developed upconversion nanoparticles (UCNPs)-based self-ratiometric fluorescent platform for the detection of chlorpyrifos. The UCNPs have the ability to confine the detection and reference functions in one nanoparticle. Specifically, the blue upconversion (UC) emission (448 nm) in the shell layer of UCNPs is quenched by the product of the acetylcholinesterase-mediated reaction, while the red UC emission (652 nm) from the core remains constant as a self-calibrated reference signal. Employing the inhibition property of chlorpyrifos, self-proportional fluorescence is employed to detect chlorpyrifos. As proof-of-concept, test strips are fabricated by loading the UCNPs onto filter paper. Combined with the smartphone and image-processing algorithm, chlorpyrifos quantitative testing is achieved with a detection limit of 14.4843 ng mL-1. This portable platform displays anti-interference capability and high stability in the complicated matrix, making it an effective candidate for on-site application.

Excessive fluoride induces ovarian function impairment by regulating levels of ferroptosis in fluorosis women and ovarian granulosa cells

The aim of this study was to investigate the role of ferroptosis in fluorosis women and the in vitro molecular mechanisms leading to ovarian dysfunction and abnormal hormone secretion by sodium fluoride (NaF) treatment of KGN cells. Fifty women with fluorosis as Fluorosis group and fifty healthy women as Control group were included in this study. The levels of lipid peroxidation and activities of antioxidant enzyme were assessed by photometric methods. The content of iron and glutathione (GSH) in serum was measured by microplate method. KGN cells were treated by different concentration of NaF (0, 1, 2, 4 and 8 ×10-3 M) for 24 h. The mRNA and protein expression levels of ferroptosis-related molecules, including glutathione peroxidase 4 (GPX4), solute carrier family 7 member (SLC7A11), nuclear factor erythroid 2-related factor 2 (Nrf2), ferritin heavy chain 1 (FTH1) and p53, were assessed by qRT-PCR and western blot analysis. Fluorosis group women had a significant higher levels of iron, Malondialdehyde (MDA), FSH and LH, and a lower levels of E2 and antioxidant enzyme in serum than that in the control group. The representative molecular changes of ferroptosis, such as the decrease in GPX4, Nrf2 and SLC7A11 expression (mRNA and protein expression), the increase in protein expression of p53, and a reduced level of E2 were observed in KGN cells treated by excessive NaF.It is concluded therefore that NaF increases the expression of p53 and inhibits ovarian granulosa cell ferroptosis preventive protein expression, resulting in abnormal hormone secretion and the ovarian dysfunction.

Ratiometric upconversion luminescence nanoprobes from construction to sensing, imaging, and phototherapeutics

In terms of the combined advantages of upconversion luminescence (UCL) properties and dual-signal ratiometric outputs toward specific targets, the ratiometric UCL nanoprobes exhibit significant applications. This review summarizes and discusses the recent advances in ratiometric UCL nanoprobes, mainly including the construction of nanoprobe systems for sensing, imaging, and phototherapeutics. First, the construction strategies are introduced, involving different types of nanoprobe systems, construction methods, and ratiometric dual-signal modes. Then, the sensing applications are summarized, involving types of targets, sensing mechanisms, sensing targets, and naked-eye visual detection of UCL colors. Afterward, the phototherapeutic applications are discussed, including bio-toxicity, bio-distribution, biosensing, and bioimaging at the level of living cells and small animals, and biomedicine therapy. Particularly, each section is commented on by discussing the state-of-the-art relevant studies on ratiometric UCL nanoprobe systems. Moreover, the current status, challenges, and perspectives in the forthcoming studies are discussed. This review facilitates the exploration of functionally luminescent nanoprobes for excellent sensing, imaging, biomedicine, and multiple applications in significant fields.

Direct Quantitative Analysis of Fluorine in Solid Samples by Cryogenic Laser Ablation and Ionization Time-of-Flight Mass Spectrometry

The determination of fluorine, the lightest element in halogens, suffers from high ionization potential and spectral interference from water molecules in mass spectrometry. Herein, we introduced a liquid nitrogen cooling unit into the laser ablation and ionization source for the first time to construct a cryogenic laser ablation and ionization time-of-flight mass spectrometry (Cryo-LAI-TOFMS) system. With this system, the interference of water-related species at m/z 19 was effectively eliminated, and fluorine atomization and ionization efficiency could reach 6.3%. A direct quantitative analysis method was developed to determine fluorine contents in phosphate rock, copper ore, industrial byproduct gypsum, stream sediment, and soil. Considering the simplicity, high sensitivity, and low spectral interference of this technique, it can be extended to the determination of fluorine content as low as μg/g in complex solid samples.

Near-Infrared-Responded High Sensitivity Nanoprobe for Steady and Visualized Detection of Albumin in Hepatic Organoids and Mouse Liver

Exploring the advanced techniques for protein detection facilitates cell fate investigation. However, it remains challenging to quantify and visualize the protein with one single probe. Here, a luminescent approach to detect hepatic cell fate marker albumin in vitro and living cell labeling with upconversion nanoparticles (UCNPs), which are conjugated with antibody (Ab) and rose bengal hexanoic acid (RBHA) is reported. To guarantee the detection quality and accuracy, an "OFF-ON" strategy is adopted: in the presence of albumin, the luminescence of nanoparticles remains suppressed owing to energy transfer to the quencher. Upon albumin binding to the antibody, the luminescence is recovered under near-infrared light. In various bio-samples, the UCNPs-Ab-RBHA (UCAR) nanoprobe can sense albumin with a broad detection range (5-315 ng mL-1 ). When applied to liver ductal organoid culture medium, the UCAR can monitor hepatocyte differentiation in real time by sensing the secreted albumin. Further, UCAR enables live imaging of cellular albumin in cells, organoids, and tissues. In a CCl4 -induced liver injury model, UCAR detects reduced albumin in liver tissue and serum. Thus, a biocompatible nanoprobe for both quantification and imaging of protein in complex biological environment with superior stability and high sensitivity is provided.

Advances in fluorescence sensing enabled by lanthanide-doped upconversion nanophosphors

Lanthanide-doped upconversion nanoparticles (UCNPs), characterized by converting low-energy excitation to high-energy emission, have attracted considerable interest due to their inherent advantages of large anti-Stokes shifts, sharp and narrow multicolor emissions, negligible autofluorescence background interference, and excellent chemical- and photo-stability. These features make them promising luminophores for sensing applications. In this review, we give a comprehensive overview of lanthanide-doped upconversion nanophosphors including the fundamental principle for the construction of UCNPs with efficient upconversion luminescence (UCL), followed by state-of-the-art strategies for the synthesis and surface modification of UCNPs, and finally describing current advances in the sensing application of upconversion-based probes for the quantitative analysis of various analytes including pH, ions, molecules, bacteria, reactive species, temperature, and pressure. In addition, emerging sensing applications like photodetection, velocimetry, electromagnetic field, and voltage sensing are highlighted.

A switchable sensor and scavenger: detection and removal of fluorinated chemical species by a luminescent metal-organic framework

Fluorosis has been regarded as a worldwide disease that seriously diminishes the quality of life through skeletal embrittlement and hepatic damage. Effective detection and removal of fluorinated chemical species such as fluoride ions (F⁻) and perfluorooctanoic acid (PFOA) from drinking water are of great importance for the sake of human health. Aiming to develop water-stable, highly selective and sensitive fluorine sensors, we have designed a new luminescent MOF In(tcpp) using a chromophore ligand 2,3,5,6-tetrakis(4-carboxyphenyl)pyrazine (H₄tcpp). In(tcpp) exhibits high sensitivity and selectivity for turn-on detection of F⁻ and turn-off detection of PFOA with a detection limit of 1.3 μg L⁻¹ and 19 μg L⁻¹, respectively. In(tcpp) also shows high recyclability and can be reused multiple times for F⁻ detection. The mechanisms of interaction between In(tcpp) and the analytes are investigated by several experiments and DFT calculations. These studies reveal insightful information concerning the nature of F⁻ and PFOA binding within the MOF structure. In addition, In(tcpp) also acts as an efficient adsorbent for the removal of F⁻ (36.7 mg g⁻¹) and PFOA (980.0 mg g⁻¹). It is the first material that is not only capable of switchable sensing of F⁻ and PFOA but also competent for removing the pollutants via different functional groups.

A robust In-MOF, In(tcpp), demonstrates sensitive detection of the fluorinated chemical species F⁻ and PFOA via distinctly different luminescence signal change, and effective adsorption and removal of both species from aqueous solution.

Blue/yellow emissive carbon dots coupled with curcumin: a hybrid sensor toward fluorescence turn-on detection of fluoride ion

Trace detection of fluoride ion has gained increasing attention due to fluoride's close association with biological and environmental processes. Herein, we construct a novel hybrid nanosystem consisting of carbon dots and curcumin for sensitive and selective sensing of F^-. Carbon dots are synthesized by hydrothermal treatment of 2,3-diaminopyridine and selenourea in hydrochloric acid. This material is employed as the fluorescent indicator that exhibits intense blue and yellow emission with quantum yields of 12% and 33%, respectively. Curcumin, possessing an absorption peak at 532 nm, can significantly quench the yellow fluorescence of carbon dots through inner filter effect. Curcumin is also used to specifically recognize F^-. When F^- is added, the curcumin-F^- complex generates, which leads to the hypochromatic shift of the absorption band from 532 to 430 nm. In such a case, the inner filter effect reduces, and yellow fluorescence of carbon dots recovers. Thus, a fluorescence turn-on sensor of F^- is built based on the carbon dots/curcumin system. The limits of detection and quantitation are measured to be 0.39 and 1.30 μM, respectively. For real usage, the proposed method is applied to determinate F^- in tap water and milk samples with relative standard deviations below 7.9%.

Fluorescence sensing of cyanide anions based on Au-modified upconversion nanoassemblies

Cyanides have been recognized as one of the most toxic chemicals and are harmful to the environment and human beings. Herein, fluorescence resonance energy transfer (FRET)-based upconversion nanoprobes for cyanide anions have been designed and prepared by assembling Au nanoparticles (NPs) on core-shell-structured NaYF₄:Yb,Er@NaYF₄:Yb upconversion NPs (csUCNPs), where csUCNPs act as the energy donor and Au NPs act as the energy acceptor. The Au content was optimized in order to have a large quenching efficiency in upconversion luminescence (UCL). The cyanide-mediated redox reaction leads to the consumption of Au NPs, resulting in UCL recovery by the inhibition of the FRET process. On the basis of these features, csUCNP/Au nanoassemblies can serve as sensitive nanoprobes for cyanide ions with a detection limit of 1.53 μM. Moreover, no significant UCL variation was observed upon the addition of other interfering ions, showing the excellent selectivity of nanoprobes toward cyanide ion sensing. The easy preparation of such upconversion-based nanoprobes provides a promising platform for sensitive and selective sensing of other hazardous species.

Cyanine-modified near-infrared upconversion nanoprobe for ratiometric sensing of N2H4 in living cells

Although being as an important chemical material in industry, hydrazine (N₂H₄) is highly toxic to the humans and animals. The development of sensitive methods for the detection of hydrazine is meaningful. Herein, we develop a new organic-inorganic hybrid nanoprobe for the detection of N₂H₄ based on luminescent resonance energy transfer (LRET) process. The nanoprobe contains N₂H₄-responsive NIR cyanine dye (CQM1) and α-cyclodextrin (CD) anchored on the surface of lanthanide-doped upconversion nanophosphors (UCNPs). In the presence of hydrazine, the hybrid materials (CQM1-UCNPs) showed the a large ratiometric luminescent signal change with high sensitivity and selectivity. More importantly, by taking advantage of ratiometric Upconversion luminescent (UCL) signal and the features of NIR emission/excitation, the nanoprobe was successfully applied for visualization of hydrazine in living cells for the first time.

Turn-on detection of glutathione S-transferase based on luminescence resonance energy transfer between near-infrared to near-infrared core-shell upconversion nanoparticles and organic dye

Glutathione S-transferase (GST) is a detoxification enzyme of the liver and kidney. Based on the toxicological effect of GST, it is of great significance to develop a rapid and sensitive detection method for GST. In this work, a new luminescence resonance energy transfer (LRET) system has been designed to detect glutathione S-transferase in the near-infrared (NIR) region by utilizing NaGdF₄:Yb³⁺,Tm³⁺@NaYF₄ upconversion nanoparticles (UCNPs) as the donor and NIR dye-806@Glutathione (IR806@GSH) as the acceptor. NaGdF₄:Yb³⁺,Tm³⁺@NaYF₄ UCNPs were synthesized by a coprecipitation method and surface modification of NOBF₄. The donor (positively charged) interacted with the acceptor (negatively charged) via electrostatic interactions to bring them into close proximity; then, LRET occurred and the luminescence was quenched. In the presence of GST, GST can specifically interact with the GSH of IR806@GSH molecule, making IR806@GSH far away from the donor surface, inhibiting the LRET, and restoring the luminescence of the UCNPs. There was a good linear relationship between the luminescence recovery intensity of UCNPs and GST concentration, ranging from 0.11 to 14.19 nM, and the detection of limit was 0.06 nM. The method has been used in the detection of GST in human serum samples and is expected to have potential applications in the biological field. Graphical abstract A luminescence resonance energy transfer system was developed for determination of glutathione S-transferase in the near-infrared region by utilizing NaGdF₄:Yb³⁺,Tm³⁺@NaYF₄ upconversion nanoparticles as the donor and NIR dye-806@Glutathione as the acceptor.

Luminescence imaging-guided triple-collaboratively enhanced photodynamic therapy by bioresponsive lanthanide-based nanomedicine

Photodynamic therapy (PDT) provides a novel sight for non-invasive tumor ablation, which, however, is still limited by low converting efficiency and short life-time of produced singlet oxygen. In this work, a bioresponsive lanthanide-based nanomedicine, FeOOH-coated and toluidine blue (TB)-loaded NaLuF₄:Yb,Er,Tm@NaLuF₄, is constructed for tumor microenvironment-activated photodynamic therapy with triple-collaborative enhancing strategy. In response to intratumoral reducibility and acidity, coated FeOOH decomposes, eliminating reduced glutathione (GSH) and up-regulating intratumoral oxidative stress to enhance PDT. Besides, Fe²⁺ is also released from this redox process, which can improve intratumoral dissolved O₂ for PDT by catalytic decomposition of H₂O₂. Lastly, quenched upconversion luminescence of lanthanide-doped nanoparticles also recovers, which allows more efficient energy transfer to TB and hence improves PDT efficiency. By the above triple-collaborative strategy, highly efficient photodynamic tumor ablation is performed in vivo. This work proposes a rigorous method to elevate photodynamic therapeutic efficiency.

Depolymerization-Induced Electrochemiluminescence of Insoluble Porphyrin in Aqueous Phase

Exploring efficient and robust electrochemiluminescence (ECL) performance of liposoluble porphyrins in aqueous phase for analytical purposes especially for important biological targets is still very challenging. In this work, a novel depolymerization-induced electrochemiluminescence (DIECL) of porphyrin and β-cyclodextrin (β-CD) self-assembly through a coreactant route was discovered. Among the studied meso-tetrasubstituted porphyrins, self-assembly of 5,10,15,20-tetrakis(4-hydroxyphenyl) porphyrin (THPP) and β-CD (THPP@β-CD) exhibits the best DIECL behavior with high efficiency (21.8%) as well as good reproducibility and stability. A mechanistic study suggests that the facile complexation of porphyrins with amphiphilic β-CD via hydrogen bonding interaction greatly improves the water insolubility and the aggregation-caused deficient ECL of liposoluble porphyrins in aqueous solution. Furthermore, because of the strong hydrogen bonding between the hydroxyl groups on THPP@β-CD and a highly electronegative substrate, such THPP@β-CD is found to serve as an efficient luminophore for recognition of most electronegative fluoride (F^-) in the aqueous phase with high sensitivity and selectivity, together with a low limit of detection (0.74 μΜ). The simplicity of this THPP@β-CD and its unique DIECL property in current work provides a new guide for the ECL applications of liposoluble porphyrins in aqueous phase.

Direct Potentiometric Sensing of Anion Concentration (Not Activity)

Potentiometric probes used in direct potentiometry are attractive sensing tools. They give information on ion activities, which is often uniquely useful. If, instead, concentrations are desired as sensor output, the ionic strength of the sample must be precisely known, which is often not possible. Here, for the first time, direct potentiometry can be made to report concentrations, rather than activities. It is demonstrated for the detection of monovalent anionic species by using a self-referencing Ag/AgI pulstrode as the reference element instead of a traditional reference electrode. This reference pulstrode releases a discrete quantity of iodide ions from the electrode and the resulting reference potential varies with the activity coefficient of iodide. The effects of activity coefficient on the indicator and reference electrode are therefore compensated and the observed cell potential may now be described in a Nernstian manner against anion concentration, rather than activity. Theoretical simulations and experimental results support the validity of this approach. For most monovalent anions of practical relevance, the potential difference between this approach and from a traditional activity coefficient calculation is less than 0.5 mV. The concept is validated with an all-solid-state nitrate sensor as well as a commercial fluoride-selective electrode, giving Nernstian responses in different ionic strength backgrounds against concentration without the need for correcting activity coefficients or liquid junction potentials.

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.

Using green emitting pH-responsive nanogels to report environmental changes within hydrogels: a nanoprobe for versatile sensing

Remotely reporting the local environment within hydrogels using inexpensive laboratory techniques has excellent potential to improve our understanding of the nanometer-scale changes that cause macroscopic swelling or deswelling. Whilst photoluminescence (PL) spectroscopy is a popular method for such studies this approach commonly requires bespoke and time-consuming synthesis to attach fluorophores which may leave toxic residues. A promising and more versatile alternative is to use a pre-formed nanogel probe that contains a donor/acceptor pair and then "dope" that into the gel during gel assembly. Here, we introduce green-emitting methacrylic acid-based nanogel probe particles and use them to report the local environment within four different gels as well as stem cells. As the swelling of the nanogel probe changes within the gels the non-radiative energy transfer efficiency is strongly altered. This efficiency change is sensitively reported using the PL ratiometric intensity from the donor and acceptor. We demonstrate that our new nanoprobes can reversibly report gel swelling changes due to five different environmental stimuli. The latter are divalent cations, gel degradation, pH changes, temperature changes and tensile strain. In the latter case, the nanoprobe rendered a nanocomposite gel mechanochromic. The results not only provide new structural insights for hierarchical natural and synthetic gels, but also demonstrate that our new green-fluorescing nanoprobes provide a viable alternative to custom fluorophore labelling for reporting the internal gel environment and its changes.

FRET-Based Upconversion Nanoprobe Sensitized by Nd3+ for the Ratiometric Detection of Hydrogen Peroxide in Vivo

The exorbitant level of hydrogen peroxide is closely related to many human diseases. The development of novel probes for H₂O₂ detection will be beneficial to disease diagnosis. In this study, a novel Nd³⁺-sensitized upconversion nanoprobe based on Förster resonance energy transfer was first developed for sensing H₂O₂. This nanosystem was made of core-shell upconversion nanoparticles (emission at 540 and 660 nm), dicyanomethylene-4 H-pyran (DCM)-H₂O₂, and poly acrylic acid (PAA)-octylamine. Obviously, upconversion nanoparticles (UCNPs) doped with Nd³⁺ acted as an energy donor, and DCM-H₂O₂, transferring to DCM-OH with the reaction of H₂O₂, acted as an energy acceptor. The ratiometric upconversion luminescence (540 nm/660 nm) signal could be utilized to visualize the H₂O₂ level, and the LOD of the nanoprobe for H₂O₂ was quantified to be 0.168 μM. Meanwhile, owing to the dope of Nd³⁺, the nanoprobe would not induce the overheating effect in biological samples and could possess deeper tissue penetration depth, compared with the UCNPs excited by 980 nm light during bioimaging. The nanoprobe could also play an important role in detecting the exogenous and endogenous H₂O₂ in living cells with ratiometric UCL (upconversion luminescence) imaging. Furthermore, our nanoprobe could function in detecting the H₂O₂ in a tumor-bearing mouse model. Therefore, this novel nanoprobe along with the ratiometric method for responding and bioimaging H₂O₂ could serve as a new model that promotes the emergence of novel probes for H₂O₂ detection.

Rationally designed pure-inorganic upconversion nanoprobes for ultra-highly selective hydrogen sulfide imaging and elimination in vivo

Lung injury is a hydrogen sulfide (H2S)-associated complication with high mortality in acute pancreatitis (AP) cases. Herein, we used Prussian Blue (PB) as a H2S-responsive acceptor to develop a novel pure-inorganic upconversion nanoprobe for detecting and eliminating H2S, which can be used for diagnosing AP and alleviating lung injury. Upconversion nanoprobes with 5 nm PB shells were optimized to achieve outstanding in vitro H2S detection capacity (linear range: 0-150 μM, LOD: 50 nM), which met the in vivo serum H2S range, and thus were feasible for imaging H2S in vivo. More importantly, when combined with the traditional H2S synthetase inhibitor dl-PAG, the nanoprobes also served as a therapeutic agent that synergistically alleviated lung injury. As PB is an FDA-approved drug, our work proposes a potential clinical modality for the early diagnosis of AP, which will decrease lung injury-induced mortality and increase the survival rates of AP cases.

A reversible fluoride chemosensor for the development of multi-input molecular logic gates

A reversible chemosensor for the development of a multi-input molecular logic gate was shown.

Artificially controlled degradable nanoparticles for contrast switch MRI and programmed cancer therapy

Background

Utilizing the permeability enhancement and irreversible biomolecule denaturation caused by hyperthermia, photothermal-chemo synergistic therapy has shown great potential in clinical cancer treatment.

Purpose

The objective of this study was to provide a novel controlled drug release method to improve the efficiency of photothermal-chemo synergistic therapy.

Patients and methods

HCT116 tumor-bearing mice were selected as modal for the study of cancer theranostics efficiency. The T2 to T1 magnetic resonance imaging contrast switch was studied in vivo. Analyses of the tumor growth of mice were carried out to evaluate the tumor therapy efficiency.

Results

We developed novel artificially controlled degradable Co₃O₄ nanoparticles and explored their potential in drug delivery/release. In the presence of ascorbic acid (AA), the designed nanomaterials can be degraded via a redox process and hence release the loaded drugs. Importantly, the AA, in the lack of l-gulonolactone oxidase, cannot be synthesized in the body of typical mammal including human, which suggested that the degradation process can be controlled artificially. Moreover, the obtained nanoparticles have outstanding photothermal conversion efficiency and their degradation can also result in an magnetic resonance imaging contrast enhancement switch from T₂ to T₁, which benefits the cancer theranostics.

Conclusion

Our results illustrated that the artificially controlled degradable nanoparticles can serve as an alternative candidate for controllable drug release as well as a platform for highly efficient photothermal-chemo synergistic cancer theranostics.

Polymer ligand-assisted fabrication of multifunctional and redox-responsive self-assembled magnetic nanoclusters for bimodal imaging and cancer treatment

We designed multifunctional magnetic nanoclusters, which can serve as bimodal imaging probes for the detection of solid tumors and act as emerging PDT agents to suppress tumor growth.