Discovery of Natural Products Alleviating Renal Fibrosis with a Viscosity-Responsive Molecular Probe.

Renal fibrosis poses a significant threat to individuals suffering from chronic progressive kidney disease. Given the absence of effective medications for treating renal fibrosis, it becomes crucial to assess the extent of fibrosis in real time and explore the development of novel drugs with substantial therapeutic benefits. Due to the accumulation of renal tissue damage and the uncontrolled deposition of fibrotic matrix during the course of the disease, there is an increase in viscosity both intracellularly and extracellularly. Therefore, a viscosity-sensitive near-infrared fluorescence (NIRF) and photoacoustic (PA) imaging probe, BDP-KY, was developed to detect aberrant changes in viscosity during fibrosis. Furthermore, BDP-KY has been applied to screen the effective components of herbal medicine, rhubarb, resulting in the identification of potential antirenal fibrotic compounds such as emodin-8-glucoside and chrysophanol 8-O-glucoside. Ultrasound, PA, and NIRF imaging of a unilateral uretera obstruction mice model show that different concentrations of emodin-8-glucoside and chrysophanol 8-O-glucoside effectively reduce viscosity levels during the renal fibrosis process. The histological results showed a significant decrease in fibrosis factors α-smooth muscle actin and collagen deposition. Combining these findings with their pharmacokinetic characteristics, these compounds have the potential to fill the current market gap for effective antirenal fibrosis drugs. This study demonstrates the potential of BDP-KY in the evaluation of renal fibrosis, and the two identified active components from rhubarb hold great promise for the treatment of renal fibrosis.

A SARS-CoV-2 Mpro fluorescent sensor for exploring pharmacodynamic substances from traditional Chinese medicine.

The main protease of SARS-CoV-2 (SARS-CoV-2 Mpro) plays a critical role in the replication and life cycle of the virus. Currently, how to screen SARS-CoV-2 Mpro inhibitors from complex traditional Chinese medicine (TCM) is the bottleneck for exploring the pharmacodynamic substances of TCM against SARS-CoV-2. In this study, a simple, cost-effective, rapid, and selective fluorescent sensor (TPE-S-TLG sensor) was designed with an AIE (aggregation-induced emission) probe (TPE-Ph-In) and the SARS-CoV-2 Mpro substrate (S-TLG). The TPE-S-TLG sensor was characterized using UV-Vis absorption spectroscopy, fluorescence spectroscopy, dynamic light scattering (DLS), transmission electron microscopy (TEM), zeta potential, and Fourier transform infrared (FTIR) spectroscopy techniques. The limit of detection of this method to detect SARS-CoV-2 Mpro was measured to be 5 ng mL-1. Furthermore, the TPE-S-TLG sensor was also successfully applied to screen Mpro inhibitors from Xuebijing injection using the separation and collection of the HPLC-fully automatic partial fraction collector (HPLC-FC). Six active compounds, including protocatechualdehyde, chlorogenic acid, hydroxysafflower yellow A, caffeic acid, isoquercetin, and pentagalloylglucose, were identified using UHPLC-Q-TOF/MS that could achieve 90% of the Mpro inhibition rate for the Xuebijing injection. Accordingly, the strategy can be broadly applied in the detection of disease-related proteases as well as screening active substances from TCM.

Novel organoboron complexes with robust core: Synthesis, functionalization, and subcellular targeting.

The construction of novel organoboron complexes with facile synthesis and unique advantages for biological imaging remains a challenge and thus has garnered considerable attention. Herein, we developed a new molecular platform, boron indolin-3-one-pyrrol (BOIN3OPY) via a two-step sequential reaction. The molecular core is robust enough to allow for post-functionalization to produce versatile dyes. When compared to the standard BODIPY, these dyes feature an N,O-bidentate seven-membered ring center, significantly redshifted absorption, and a larger Stokes shift. This study establishes a new molecular platform that provides more flexibility for the functional regulation of dyes.

A Multichannel Fluorescent Array Sensor for Discrimination of Different Types of Drug-Induced Kidney Injury.

The differences in urinary proteins could provide a novel opportunity to distinguish the different types of drug-induced kidney injury (DIKI). In this research, Au nanoparticles-polyethyleneimine (AuNPs-PEI) and the three fluorophore-labeled proteins (FLPs) have been constructed as a multichannel fluorescent array sensor via electrostatic interaction, which was used to detect the subtle changes in urine collected from the pathological state of DIKI. Once the urine from different types of DIKI was introduced, the binding equilibrium between AuNPs-PEI and FLPs would be broken due to the competitive binding of urinary protein, and the corresponding fluorescence response pattern would be generated. Depending on the different fluorescence response patterns, the different types of DIKI were successfully identified by principal component analysis (PCA) and linear discriminant analysis (LDA). Accordingly, the strategy was expected to be a powerful technique for evaluating the potential unclear mechanisms of nephrotoxic drugs, which would provide a promising method for screening potential renal-protective drugs.

Near-Infrared Photoacoustic Probe for Reversible Imaging of the ClO-/GSH Redox Cycle In Vivo.

Homeostasis of the cellular redox status plays an indispensable role in diverse physiological and pathological processes. Hypochlorite anion (ClO-) and glutathione (GSH) represent an important redox couple to reflect the redox status in living cells. The current cellular redox probes that detect either ClO- or GSH alone are not accurate enough to monitor the real redox status. In this work, a reversible photoacoustic (PA) probe, DiOH-BDP, has been synthesized and applied for PA imaging to monitor the ClO-/GSH couple redox state in an acute liver injury (ALI) model. The near-infrared PA probe DiOH-BDP features significant changes in absorption between 648 and 795 nm during the selective oxidation by ClO- and the reductive recovery of GSH, which exhibits excellent selectivity and sensitivity toward ClO- and GSH with the limits of detection of 77.7 nM and 7.2 µM, respectively. Additionally, using PA770 as a detection signal allows for the in situ monitoring of the ClO-/GSH couple, which realizes mapping of the localized redox status of the ALI by the virtue of a PA imaging system. Therefore, the probe provides a potentially technical tool to understand redox imbalance-related pathological formation processes.

Small-Molecule Photoacoustic Imaging Probe with Aggregation-Enhanced Amplitude for Real-Time Visualization of Acute Kidney Injury.

Acute kidney injury (AKI) has become a growing issue for patients with the extensive use of all kinds of drugs in clinic. Photoacoustic (PA) imaging provides a noninvasive and real-time imaging method for studying kidney injury, but it has inherent shortages in terms of high background signal and low detection sensitivity for exogenous imaging agents. Intriguingly, J-aggregation offers to tune the optical properties of the dyes, thus providing a platform for developing new PA probes with desired performance. In this study, a small-molecule PA probe (BDP-3) was designed and synthesized. We serendipitously discovered that BDP-3 can transform into renal clearable nanoaggregates under physiological conditions. The hydrodynamic diameter of the BDP-3 increased from 0.64 ± 0.11 to 3.74 ± 0.39 nm when the content of H2O increased from 40 to 90%. In addition, it was surprising that such a transforming process can significantly enhance its PA amplitude (2.06-fold). On this basis, PA imaging with BDP-3 was applied as a new method for the noninvasive detection of AKI induced by anticancer drugs, traditional Chinese medicine, and clinical contrast agents in animal models and exhibited higher sensitivity than the conventional serum index test, demonstrating great potential for further clinical diagnostic applications.

Accurate identification of kidney injury progression via a fluorescent biosensor array.

Identifying the progress of kidney injury may aid the effective treatment and intervention. Herein, we developed a fluorescent biosensor array for instantaneous and accurate identification of the kidney injury progression via "doubled" signals. The multichannel biosensor array consisted of polydopamine-polyethyleneimine (PDA-PEI) and multicolor-labelled different length of DNAs including AAAAA-Cyanine7 (5A-Cy7), AAAAAAAAAA-Texas Red (10A-Texas Red), and AAAAAAAAAAAAAAAAAAAA-VIC (20A-VIC). Facing to the variety of protein in urine with alterable charge accompanied with different progress of kidney injury, the composition of urine replaces the DNA signal molecules, forming their special fluorescence patterns. Taking the size of protein into consideration, the original three variables induced by the protein charge were extended to six variables induced by the two factors of protein particle size and charge difference, which could provide a more accurate strategy to identify the progress of kidney injury. Notably, this strategy not only opened up new perspective for identification the progress of kidney injury via the size and charge of urine protein, but also improved the resolving power of sensor array by increasing the number of sensor elements for extending their potential application to various diseases.

B/N-Doped p-Arylenevinylene Chromophores: Synthesis, Properties, and Microcrystal Electron Crystallographic Study.

Linearly conjugated systems have long served as an archetype of conjugated materials, but suffer from two intrinsic structural problems: potential instability due to intermolecular interactions and the flexibility of the C-C bonds connecting C═C bonds. Efforts to solve these problems have included the insertion of aromatic units as a part of the conjugation and the introduction of carbon bridges to stop the bond rotation. We report here B/N-doped p-arylenevinylene chromophores synthesized through the incorporation of a cyclopenta[c][1,2]azaborole framework as a part of the conjugated system. The ring strain intrinsic to this new skeleton both flattens and rigidifies the conjugation, and the B--N+ dative bond is much easier to form than a C-C bond, which simplifies the synthetic design. The B-N dative bond also reduces the HOMO-LUMO gap, thereby causing a significant redshift of the absorption and emission compared with their all-carbon congeners while retaining high photostability and high fluorescence quantum yield in both solution and film states. A doubly B/N-doped compound showed emission peaks at 540 nm with a small Stokes shift of 20 nm and a fluorescence quantum yield of 98%. The molecules serve as excellent lipophilic fluorescent dyes for live-cell imaging, showing a higher photostability than that of commercially available BODIPY-based dyes.

Rapid and sensitive detection of NGAL for the prediction of acute kidney injury via a polydopamine nanosphere/aptamer nanocomplex coupled with DNase I-assisted recycling amplification.

Early detection of acute kidney injury (AKI) is important, as early intervention and treatment can prevent further kidney injury and improve kidney health. Neutrophil gelatinase-associated lipocalin (NGAL) has emerged as the earliest and promising non-invasive biomarker of AKI in urine, and has been used as a new predictive biomarker of AKI in the bench-to-bedside journey. In this work, a nanocomplex composed of a polydopamine nanosphere (PDANS) and a fluorophore-labelled aptamer has been constructed for the detection of NGAL using a DNase I-assisted recycling amplification strategy. After the addition of NGAL, the fluorescence intensity increases linearly over the NGAL concentration range from 12.5 to 400 pg mL-1. The limit of detection of this strategy is found to be 6.25 pg mL-1, which is almost 5 times lower than that of the method that does not involve DNase I. The process can be completed within 1 h, indicating a fast fluorescence response. Furthermore, the method using the nanocomplex coupled with DNase I has been successfully utilized for the detection of NGAL in the urine from cisplatin-induced AKI and five-sixths nephrectomized mice, demonstrating its promising ability for the early prediction of AKI. This method also demonstrates the protective effect of the Huangkui capsule on AKI, and provides an effective way to screen potentially protective drugs for renal disease.

Targeted Myocardial Hypoxia Imaging Using a Nitroreductase-Activatable Near-Infrared Fluorescent Nanoprobe.

Development of a highly selective and sensitive imaging probe for accurate detection of myocardial hypoxia will be helpful to estimate the degree of ischemia and subsequently guide personalized treatment. However, an efficient optical approach for hypoxia monitoring in myocardial ischemia is still lacking. In this work, a cardiomyocyte-specific and nitroreductase-activatable near-infrared nanoprobe has been developed for selective and sensitive imaging of myocardial hypoxia. The nanoprobe is a liposome-based nanoarchitecture which is functionalized with a peptide (GGGGDRVYIHPF) for targeting heart cells and encapsulating a nitrobenzene-substituted BODIPY for nitroreductase imaging. The nanoprobe can specifically recognize and bind to angiotensin II type 1 receptor that is overexpressed on the ischemic heart cells by the peptide and is subsequently uptaken into heart cells, in which the probe is released and activated by hypoxia-related nitroreductase to produce fluorescence emission at 713 nm. The in vitro response of the nanoprobe toward nitroreductase resulted in 55-fold fluorescence enhancement with the limit of detection as low as 7.08 ng/mL. Confocal fluorescence imaging confirmed the successful uptake of nanoprobe by hypoxic heart cells and intracellular detection of nitroreductase. More significantly, in vivo imaging of hypoxia in a murine model of myocardial ischemia was achieved by the nanoprobe with high sensitivity and good biocompatibility. Therefore, this work presents a new tool for targeted detection of myocardial hypoxia and will promote the investigation of the hypoxia-related physiological and pathological process of ischemic heart disease.

Multifunctional Fe3O4@Polydopamine@DNA-Fueled Molecular Machine for Magnetically Targeted Intracellular Zn2+ Imaging and Fluorescence/MRI Guided Photodynamic-Photothermal Therapy.

For the precise treatment of tumors, it is necessary to develop a theranostic nanoplatform that has both diagnostic and therapeutic functions. In this article, we designed a new theranostic probe for fluorescence imaging of Zn2+ and fluorescence/MRI guided magnetically targeted photodynamic-photothermal therapy. The fluorescence imaging of Zn2+ was based on an endogenous ATP-driven DNA nanomachine that could perform repetitive stand displacement reaction. It modifies all units on a single PDA/Fe3O4 nanoparticle containing a hairpin-locked initiated strand activated by a target molecule in cells, a two-stranded fuel DNA triggered by ATP, and a two-stranded DNA track responding to an initiated strand and fuel DNA. After entering the cell, the intracellular target Zn2+ initiates the nanomachine via an autocatalytic cleavage reaction, and the machine programmatically and gradually runs on the assembled DNA track via fuel DNA driving and the intramolecular toehold-mediated stand displacement reaction. The Fe3O4 core first exhibits magnetic targeting, increasing the ability of nanoparticles to enter tumor cells at the tumor site. The Fe3O4 could also be employed as a powerful magnetic resonance imaging (MRI) contrast agent and guided therapy. Using 808 nm laser and 635 nm laser irradiation together at the tumor site, the PDA nanoshell produced an excellent photothermal effect and the TMPyP4 molecules entering the cell generated reactive oxygen species, followed by cell damage. A series of reliable experiments suggested that the Fe3O4@PDA@DNA nanoprobe showed superior fluorescence specificity, MRI, a remarkable photothermal/photodynamic therapy effect, and favorable biocompatibility. This theranostic nanoplatform offered a split-new insight into tumor fluorescence and MRI diagnosis as well as effective tumor therapy.

A hairpin DNA-fueled nanoflare for simultaneous illumination of two microRNAs in drug-induced nephrotoxic cells with target catalytic recycling amplification.

The detection of specific extracellular microRNAs (miRNAs) is beneficial for the prediction of drug-induced kidney injury. Here, a novel hairpin DNA-fueled nanoflare was developed for the simultaneous detection of drug-induced nephrotoxicity-related miRNA-21 and miRNA-200c with target catalytic recycling amplification. The nanoflare utilized gold nanoparticles (AuNPs) as the highly efficient quencher to ensure a low background signal. With the help of the fueled hairpin DNA, the miRNA targets could serve as the catalysts for the assembly of DNA duplexes. Therefore, the nanoflare could respond to the miRNAs to yield signal outputs of 1 : n (target : signal) rather than an equivalent reaction ratio of 1 : 1, achieving the signal amplified detection of low-abundant miRNAs. The targets can be concurrently detected with the detection limit of 18.1 and 21.1 pM for miRNA-21 and miRNA-200c, respectively, which are approximately 2 orders of magnitude lower than that of the non-catalytic probes. In addition, this nanoflare offered a high selectivity for determination between perfectly matched targets and single-base mismatched targets. It should be noted that the nanoflare was successfully employed to predict the drug-induced nephrotoxicity by the detection of miRNAs in culture media excreted from the drug-treated renal cells using a fluorescent microplate reader. Our hairpin DNA-fueled nanoflare could also accurately detect the divergence of miRNA-21 and miRNA-200c between drug-treated nephrotoxic cells and tumor cells, demonstrating a promising potential for exploring the pathogenesis of drugs and auxiliary diagnosis of drug-induced nephrotoxicity.

Prediction of Drug-Induced Nephrotoxicity with a Hydroxyl Radical and Caspase Light-Up Dual-Signal Nanoprobe.

The development of well-designed nanoprobes for specific imaging of multiple biomarkers in renal cells will afford beneficial information related to the transmutation process of drug-induced kidney injury (DIKI). However, the most reported nanoprobes for DIKI detection were dependent on single-signal output and lack of kidney targeting. In this work, we reported a renal cell targeting and dual-signal nanoprobe by encapsulating Brite 670 and Dabcyl-KFFFDEVDK-FAM into a low molecular weight chitosan nanoparticle. Confocal fluorescence imaging results demonstrated that the nanoprobe could visualize the upregulation of hydroxyl radical in early stage and activation of caspase-3 in late stage of DIKI at both the renal cell and tissue level. In a mouse DIKI model, the positive time of 8 h using nanoprobe imaging was superior to that of 72 h for serum creatinine or blood urea nitrogen, 16 h for cystatin-C, and 24 h for kidney injury molecule-1 with conventional methods. These results demonstrated that the nanoprobe may be a promising tool for effective early prediction and discriminative imaging of DIKI.

H2O2-activatable and O2-evolving nanoparticles for highly efficient and selective photodynamic therapy against hypoxic tumor cells.

The low selectivity of currently available photosensitizers, which causes the treatment-related toxicity and side effects on adjacent normal tissues, is a major limitation for clinical photodynamic therapy (PDT) against cancer. Moreover, since PDT process is strongly oxygen dependent, its therapeutic effect is seriously hindered in hypoxic tumor cells. To overcome these problems, a cell-specific, H(2)O(2)-activatable, and O(2)-evolving PDT nanoparticle (HAOP NP) is developed for highly selective and efficient cancer treatment. The nanoparticle is composed of photosensitizer and catalase in the aqueous core, black hole quencher in the polymeric shell, and functionalized with a tumor targeting ligand c(RGDfK). Once HAOP NP is selectively taken up by α(v)ß(3) integrin-rich tumor cells, the intracellular H(2)O(2) penetrates the shell into the core and is catalyzed by catalase to generate O(2), leading to the shell rupture and release of photosensitizer. Under irradiation, the released photosensitizer induces the formation of cytotoxic singlet oxygen ((1)O(2)) in the presence of O(2) to kill cancer cells. The cell-specific and H(2)O(2)-activatable generation of (1)O(2) selectively destroys cancer cells and prevents the damage to normal cells. More significantly, HAOP NP continuously generates O(2) in PDT process, which greatly improves the PDT efficacy in hypoxic tumor. Therefore, this work presents a new paradigm for H(2)O(2)-triggered PDT against cancer cells and provides a new avenue for overcoming hypoxia to achieve effective treatment of solid tumors.

Folate receptor-targeted and cathepsin B-activatable nanoprobe for in situ therapeutic monitoring of photosensitive cell death.

The integration of diagnostic and therapeutic functions in a single system holds great promise to enhance the theranostic efficacy and prevent the under- or overtreatment. Herein, a folate receptor-targeted and cathepsin B-activatable nanoprobe is designed for background-free cancer imaging and selective therapy. The nanoprobe is prepared by noncovalently assembling phospholipid-poly(ethylene oxide) modified folate and photosensitizer-labeled peptide on the surface of graphene oxide. After selective uptake of the nanoprobe into lysosome of cancer cells via folate receptor-mediated endocytosis, the peptide can be cleaved to release the photosensitizer in the presence of cancer-associated cathepsin B, which leads to 18-fold fluorescence enhancement for cancer discrimination and specific detection of intracellular cathepsin B. Under irradiation, the released photosensitizer induces the formation of cytotoxic singlet oxygen for triggering photosensitive lysosomal cell death. After lysosomal destruction, the lighted photosensitizer diffuses from lysosome into cytoplasm, which provides a visible method for in situ monitoring of therapeutic efficacy. The nanoprobe exhibits negligible dark toxicity and high phototoxicity with the cell mortality rate of 0.06% and 72.1%, respectively, and the latter is specific to folate receptor-positive cancer cells. Therefore, this work provides a simple but powerful protocol with great potential in precise cancer imaging, therapy, and therapeutic monitoring.

Porphodilactones as synthetic chlorophylls: relative orientation of ß-substituents on a pyrrolic ring tunes NIR absorption.

Porphodilactones represent the porphyrin analogues, in which the peripheral bonds of two pyrrole rings are replaced by lactone moieties. They provide an opportunity to investigate how ß-substituent orientation of porphyrinoids modulates the electronic structures and optical properties, in a manner similar to what is observed with naturally occurring chlorophylls. In this work, a comprehensive description of the synthesis, characterization, and optical properties of meso-tetrakispentafluorophenylporphodilactone isomers is first reported. The ß-dilactone moieties are found to lie at opposite pyrrole positions (trans- and cis-configurations are defined by the relative orientations of the carbonyl group when one lactone moiety is fixed), in accordance with earlier computational predictions (Gouterman, M. J. Am. Chem. Soc. 1989, 111, 3702). The relative orientation of the ß-dilactone moieties has a significant influence on the electronic structures and photophysical properties. For example, the Qy band of trans-porphodilactone is red-shifted by 19 nm relative to that of the cis-isomer, and there is a 2-fold increase in the absorption intensity, which resembles the similar trends that have been reported for natural chlorophyll f and d. An in depth analysis of magnetic circular dichroism spectral data and TD-DFT calculations at the B3LYP/6-31G(d) level of theory demonstrates that the trans- and cis-orientations of the dilactone moieties have a significant effect on the relative energies of the frontier π-molecular orbitals. Importantly, the biological behaviors of the isomers reveal their different photocytotoxicity in NIR region (>650 nm). The influence of the relative orientation of the ß-substituents on the optical properties in this context provides new insights into the electronic structures of porphyrinoids which could prove useful during the development of near-infrared absorbing photosensitizers.

A multifunctional nanomicelle for real-time targeted imaging and precise near-infrared cancer therapy.

Simultaneous targeted cancer imaging, therapy and real-time therapeutic monitoring can prevent over- or undertreatment. This work describes the design of a multifunctional nanomicelle for recognition and precise near-infrared (NIR) cancer therapy. The nanomicelle encapsulates a new pH-activatable fluorescent probe and a robust NIR photosensitizer, R16FP, and is functionalized with a newly screened cancer-specific aptamer for targeting viable cancer cells. The fluorescent probe can light up the lysosomes for real-time imaging. Upon NIR irradiation, R16FP-mediated generation of reactive oxygen species causes lysosomal destruction and subsequently trigger lysosomal cell death. Meanwhile the fluorescent probe can reflect the cellular status and in situ visualize the treatment process. This protocol can provide molecular information for precise therapy and therapeutic monitoring.

Discovering a New Drug Against Acute Kidney Injury by Using a Tailored Photoacoustic Imaging Probe.

Acute kidney injury (AKI) has become an increasing concern for patients due to the widespread clinical use of nephrotoxic drugs. Currently, the early diagnosis of AKI is still challenging and the available therapeutic drugs cannot meet the clinical demand. Herein, this work has investigated the key redox couple involved in AKI and develops a tailored photoacoustic (PA) imaging probe (AB-DiOH) which can reversibly respond to hypochlorite (ClO-)/glutathione (GSH) with high specificity and sensitivity. This probe enables the real-time monitoring of AKI by noninvasive PA imaging, with better detection sensitivity than the blood test. Furthermore, this probe is utilized for screening nephroprotective drugs among natural products. For the first time, astragalin is discovered to be a potential new drug for the treatment of AKI. After oral administration, astragalin can be efficiently absorbed by the animal body, alleviate kidney injury, and meanwhile induce no damage to other normal tissues. The treatment mechanism of astragalin has also been revealed to be the simultaneous inhibition of oxidative stress, ferroptosis, and cuproposis. The developed PA imaging probe and the discovered drug candidate provide a promising new tool and strategy for the early diagnosis and effective treatment of AKI.

Rational design of CT-coupled J-aggregation platform based on Aza-BODIPY for highly efficient phototherapy.

Supramolecular engineering is exceptionally appealing in the design of functional materials, and J-aggregates resulting from noncovalent interactions offer intriguing features. However, building J-aggregation platforms remains a significant challenge. Herein, we report 3,5-dithienyl Aza-BODIPYs with a donor-acceptor-donor (D-A-D) architecture as the first charge transfer (CT)-coupled J-aggregation BODIPY-type platform. The core acceptor moieties in one molecule interact with donor units in neighboring molecules to generate slip-stacked packing motifs, resulting in CT-coupled J-aggregation with a redshifted wavelength up to 886 nm and an absorption tail over 1100 nm. The J-aggregates show significant photoacoustic signals and high photothermal conversion efficiency of 66%. The results obtained in vivo show that the J-aggregates have the potential to be used for tumor photothermal ablation and photoacoustic imaging. This study not only demonstrates Aza-BODIPY with D-A-D as a novel CT-coupled J-aggregation platform for NIR phototherapy materials but also motivates further study on the design of J-aggregation.

Cell-specific and pH-activatable rubyrin-loaded nanoparticles for highly selective near-infrared photodynamic therapy against cancer.

Spatiotemporal control of singlet oxygen ((1)O2) release is a major challenge for photodynamic therapy (PDT) against cancer with high therapeutic efficacy and minimum side effects. Here a selenium-rubyrin (NMe2Se4N2)-loaded nanoparticle functionalized with folate (FA) was designed and synthesized as an acidic pH-activatable targeted photosensitizer. The nanoparticles could specifically recognize cancer cells via the FA-FA receptor binding and were selectively taken up by cancer cells via receptor-mediated endocytosis to enter lysosomes, in which NMe2Se4N2 was activated to produce (1)O2. The pH-controllable release of (1)O2 specially damaged the lysosomes and thus killed cancer cells in a lysosome-associated pathway. The introduction of selenium into the rubyrin core enhanced the (1)O2 generation efficiency due to the heavy atom effect, and the substitution of dimethylaminophenyl moiety at meso-position led to the pH-controllable activation of NMe2Se4N2. Under near-infrared (NIR) irradiation, NMe2Se4N2 possessed high singlet oxygen quantum yield (ΦΔ) at an acidic pH (ΦΔ = 0.69 at pH 5.0 at 635 nm) and could be deactivated at physiological pH (ΦΔ = 0.06 at pH 7.4 at 635 nm). The subcellular location-confined pH-activatable photosensitization at NIR region and the cancer cell-targeting feature led to excellent capability to selectively kill cancer cells and prevent the damage to normal cells, which greatly lowered the side effects. Through intravenous injection of FA-NMe2Se4N2 nanoparticles in tumor-bearing mice, tumor elimination was observed after NIR irradiation. This work presents a new paradigm for specific PDT against cancer and provides a new avenue for preparation of highly efficient photosensitizers.