Photostability Of Dyes Research Articles

Clickable HaloTag ligands for live cell labeling and imaging

Self-labeling protein (SLP) tags, such as HaloTag, have gained considerable interest as advanced tools for live cell labeling. However, the chloroalkane-based substrates that can be directly used for protein labeling are limited. Here, we report two bioorthogonal small molecule linkers, chloroalkane-tetrazine (CA-Tz) and chloroalkane-azide (CA-N3), which can penetrate cell membranes and facilitate click chemistry-based labeling in live cells. We compare their labeling capability using two clickable silicon rhodamine dyes (SiR-PEG3-TCO and SiR-PEG4-DBCO). Confocal imaging results demonstrate that using CA-Tz and SiR-PEG3-TCO dye exhibits superior intracellular labeling with low nonspecific signals. We subsequently compared the photostability of SiR dyes with that of green fluorescent proteins (mEmerald). Total internal reflection fluorescence (TIRF) imaging indicates that SiR dyes exhibit superior photostability under identical excitation conditions, making them suitable for long-term cell imaging. Furthermore, SiR dyes labeling also shows high structure retention for the fourth-order super-resolution optical fluctuation imaging (SOFI) compared to fluorescent proteins. This study presents clickable HaloTag linkers as effective tools for live cell labeling and imaging, highlighting the high-quality labeling of chloroalkane linkers and clickable dyes for live cell imaging.

Stabilizing Dye-Sensitized Upconversion Hybrids by Cyclooctatetraene.

Lanthanide-doped upconversion nanoparticles (UCNPs) can convert low-energy near-infrared (NIR) light into high-energy visible light, making them valuable for broad applications. UCNPs often suffer from poor light-harvesting capabilities, which can be significantly improved by incorporating organic dye antennas. However, the dye-sensitized upconversion systems are prone to severe photobleaching in an ambient atmosphere. Here, we present a synergistic approach to mitigate photobleaching by introducing triplet state quencher cyclooctatetraene (COT). COT effectively suppresses the generation of singlet oxygen by quenching the triplet states of the dye and consumes the existing singlet oxygen through oxidant reactions. The inclusion of COT extends the half-life of IR806 by 4.7-times by preventing the oxidation of its poly(methylene) chains. Without significantly affecting emission intensity and dynamics, COT effectively stabilized dye-UCNPs, demonstrating a notable 3.9-fold increase in half-life under continuous laser irradiation. Our findings suggest a new strategy to enhance the photostability of near-infrared dyes and dye-sensitized upconversion nanohybrids.

Milk Exosome-Glow Nanosystem for Cancer Cellular and Tissue Bioimaging.

Milk-derived exosomes are widely used for diagnosis, delivery, imaging, and theranostic applications. Near-Infrared (NIR) based fluorescence bioimaging is an attractive and safer technique that is used for clinical applications. However, almost all NIR imaging agents tend to have poor photostability, short half-life, nonspecific protein binding, and concentration-dependent aggregation(s). Therefore, there is an unmet clinical need to develop newer and safer modalities to package and deliver NIR imaging agents. Bovine milk exosomes are natural, biocompatible, safe, and efficient nanocarriers that facilitate the delivery of micro- and macromolecules. Herein, we developed an exosome-based NIR dye loaded nanoimaging formulation that offers improved solubility and photostability of NIR dye. Following the acetic acid based extracellular vesicle (EV) treatment method, we extracted the bovine milk exosomes from a variety of pasteurized grade milk. The EVs were screened for their physicochemical properties such as particle size and concentration and zeta potential. The stability of these exosomes was also determined under different conditions, including storage temperatures, pH, and salt concentrations. Next, indocyanine green, a model NIR dye was loaded into these exosomes (Exo-Glow) via a sonication method and further assessed for their improved fluorescence intensity and photostability using an IVIS imaging system. Initial screening suggested that size of the selected bovine milk exosomes was ∼100-135 nm with an average particle concentration of 5.8 × 102 particles/mL. Exo-Glow further demonstrated higher fluorescence intensity in cancer cells and tissues when compared to free dye. These results showed that Exo-Glow has the potential to serve as a safer NIR imaging tool for cancer cells/tissues.

Fluorescent Carbon Dots from Bamboo Stem Waste: Synthesis, Characterization, and Inkjet Printing

AbstractAmong the various anti‐counterfeiting solutions, fluorescent compounds gained attention as challenging to copy solutions because of astute technological improvements. However, fluorescent compound usage in counterfeit detection is limited due to high price of rare earth metals, the low photostability of pigments or organic dyes, and the long‐term toxicity of conventional semiconductor quantum dots. Herein lies the value of carbon dot, a very stable, reasonably priced, and environmentally friendly material with intriguing features. In this work the development of blue fluorescent, N‐doped carbon dots (NCD) from waste bamboo stem cuttings via hydrothermal route is presented as an environmentally friendly approach to reduce the risk of toxic gas evolution from burning of bamboo waste. The carbon dot's practical application in anti‐counterfeit printing was ascertained by comprehending it's superior properties, such as high water solubility, eco‐friendliness, dazzling fluorescence, and surface functionalization through various characterization techniques. Inkjet printing of the designs on paper substrate using the aqueous NCD ink displayed reversible encryption‐decryption ability through variation of pH. The development paves the way for value‐added utilization of waste bamboo cuttings in fluorescent ink production.

Visualization and Characterization of the Brain Regional Heterogeneity of Astrocyte-Astrocyte Structural Interactions by Using Improved Iontophoresis with Dual-Fluorescent Dyes.

Astrocytes are morphologically intricate cells and actively modulate the function of the brain. Through numerous fine processes, astrocytes come into contact with neurons, blood vessels, and other glia cells. Emerging evidence has shown that astrocytes exhibit brain regional diversity in their morphology, transcriptome, calcium signaling, and functions. However, little is known about the brain regional heterogeneity of astrocyte-astrocyte structural interaction. So far, the visualization and characterization of the morphological features of adjacent astrocytes have been difficult, and as a result, it is still well-accepted that astrocytes in the adult brain share non-overlapped territory. In contrast, employing an approach that combines viral labeling with dual-fluorescent dyes iontophoresis under brightfield and imaging using confocal microscopy allows for the efficient and specific labeling of adjacent astrocytes, enabling a comprehensive visualization of their fine processes and the degree of their territorial overlap. Our study in the hypothalamic regions of the brain revealed a marked spatial overlap among adjacent astrocytes, which differs from the conventional understanding based on more extensively studied regions, like the hippocampus. Additionally, we revealed the heterogeneity of the astrocyte-neuron ratio across brain regions and conducted an assessment of the photostability and labeling efficiency of fluorescent dyes used for labeling adjacent astrocytes. Our study provides new insights for studying the morphological heterogeneity of astrocytes across the central nervous system.

The dark side of cyclooctatetraene (COT): Photophysics in the singlet states of “self-healing” dyes

Cyclooctatetraene (COT) attachment to fluorophores (“self-healing” dyes) is known for quenching reactive triplet states via triplet-state energy transfer (TET), enhancing photostability. However, COT's impact on singlet states remains unclear. Quantum calculations reveal that COT induces energy transfer to dark states in deep blue dyes while promoting photoinduced electron transfer (PET) and intersystem crossing (ISC) in visible dyes, potentially compromising brightness and/or photostability. To address this, we propose the use of ΔE descriptor to optimize COT's effects. Our findings uncover COT's multifaceted impact. These insights will guide the development of superior triplet state quenchers and photostable dyes.

Insight into the relationship between the photostability and molecular structure of rhodamine dyes

It is still challenging to clarify the intrinsic relationship between the photostability and molecular structures of rhodamine dyes. Herein, we investigated the photostability of three rhodamine dyes RhB, Rh101, and Rh101-ME in water and 20%EtOH–H2O solutions under 525 nm LED light irradiation. The photostability of RhB is much higher than that of Rh 101 and Rh101-ME, indicating that forming rigid ring between the N-linked alkyl and xanthene can significantly decrease the photostability of rhodamine dyes, while the esterification of carboxyl on benzene ring can improve their photostability. The EPR analyses and radical trapping experiments proved that 1O2 is the most important reactive oxygen species responsible for dye degradation, and the Rh101 and Rh101-ME have higher 1O2 and •OH production rates than RhB. The cyclic voltammetry tests showed that forming rigid ring between the N-linked alkyls and xanthene can decrease the oxidation potential of RhB and consequently lower down its photostability. The theoretical calculations disclosed that the higher HOMO energy levels in ground states and lower singlet–triplet energy gaps of Rh101 and Rh101-ME are the main factor that results in their lower photostability when compared with RhB.

A Study of the Electronic Absorption and Emission Spectra of DBDMA Dye: Solvent Effect, Energy Transfer, and Fluorescence Quenching

This study is aimed to shed light on the electronic absorption and emission spectra of DBDMA (2-(1-(difluoroboraneyl)-1,2-dihydroquinolin-2-yl)-2-(1-methylquinoxalin-2-ylidene) acetonitrile) in different solvents. Both types of spectra were obtained theoretically and produced experimentally in different solvents. The photostability of dye was tested, and its energy transfer behavior in the presence of oxygen and hydrated copper sulfate quenchers was investigated. We also gave a qualitative estimation of the effect of acidic media on the absorption and emission spectra. There is good compatibility between the calculated and measured values of many photophysical parameters. DBDMA has a low chemical quantum yield in solvents of different polarities, and the fluorescence quantum yield is high enough, which confirms, together with the low values of the excited state lifetime, its efficiency as laser emitting dye in the range of wavelength emission maxima. The rigidity of the DBDMA molecule is the main reason for the photochemical stability and the absence of a considerable shift as a result of the change in the polarity of the solvents. Geometries of ground and excited states were optimized using the density functional theory (DFT) and the time-dependent density functional theory (TD-DFT), respectively. Upon using the TD-DFT method, the UV-Vis absorption and emission spectra of the DBDMA molecule in different solvents were illustrated. A slight change is observed in the position of the maximum emission and absorption wavelength with the change of the solvent due to the rigidity of the compound. There was no apparent effect of quenching by oxygen. Besides, no intersystem crossing (ISC) was observed for the excited state of the DBDMA as a result of aeration of a solution with O2 for 20 min, which was an explanation of the stability of peak emission intensity of dye after exposure to oxygen gas. The energy transfer rate constant has been calculated as well.

Influences of molecular structures on the spectral properties and photostability of rhodamine dyes

Influences of molecular structures on the spectral properties and photostability of rhodamine dyes

Photoselective particle films influence physiology and growth of citrus

Particle films impact pest management and crop physiology by redistributing light within the canopy. Although most commercial particle film products have nonselective reflectance, recent studies found positive effects of a red-dyed particle film on pest suppression and growth in citrus. To better understand the impacts of photoselective particle films on tree physiology and growth, we implemented a series of trials in citrus. Photoselective particle films of white (undyed), red, blue, purple, and green color were developed using photostable dyes. The experiment was repeated three times. In Trials 1 and 2 treatment rates were the same quantity of kaolin per treatment. However, because different photoselective films provided differences in shading, in Trial 3 the kaolin rates were adjusted to result in the same incident radiation to the leaves. We measured gas exchange and leaf temperatures midmorning and midday on multiple dates. All particle film treatments reduced leaf temperature (∼ 4–8 °C). Depending on environmental conditions, some particle films increased net CO2 assimilation or stomatal conductance especially white and red. Trees growing under red and white films resulted in higher total dry weights compared to the other colored films, and red films had the highest mean in all three trials. Photoselective particle films impacted both quantity and quality of incident radiation. The red-dyed kaolin film resulted in the best growth and physiological responses in citrus. These products represent an easily deployable technology to manipulate the light environment of crops in the field.

SIM imaging resolves endocytosis of SARS-CoV-2 spike RBD in living cells

It is urgent to understand the infection mechanism of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) for the prevention and treatment of COVID-19. The infection of SARS-CoV-2 starts when the receptor-binding domain (RBD) of viral spike protein binds to angiotensin-converting enzyme 2 (ACE2) of the host cell, but the endocytosis details after this binding are not clear. Here, RBD and ACE2 were genetically coded and labeled with organic dyes to track RBD endocytosis in living cells. The photostable dyes enable long-term structured illumination microscopy (SIM) imaging and to quantify RBD-ACE2 binding (RAB) by the intensity ratio of RBD/ACE2 fluorescence. We resolved RAB endocytosis in living cells, including RBD-ACE2 recognition, cofactor-regulated membrane internalization, RAB-bearing vesicle formation and transport, RAB degradation, and downregulation of ACE2. The RAB was found to activate the RBD internalization. After vesicles were transported and matured within cells, RAB was finally degraded after being taken up by lysosomes. This strategy is a promising tool to understand the infection mechanism of SARS-CoV-2.

N1-aryl-2-(trifluoromethyl)benzo[b][1,8]naphthyridin-4(1H)-one as convenient platform to design high photostable and long-lived dyad fluorophore with potential application in live-cell imaging

The design of long-lived and high photostable fluorescent probes with high quantum yields (QYs) is of great significance for biological applications. It favors the monitoring of individual molecular events for extended period of time without side-effect consequences into cell. From a series of N1-aryl-2-(trifluoromethyl)benzo[b][1,8]naphthyridin-4(1H)-ones, we found that their photophysical properties were successfully tuned through the modulation of the intramolecular charge-transfer (ICT), generating the largest lifetimes, highest QYs and photostability for those fluorophores with a high CT character. The ICT was primarily controlled by incorporation of methoxy group at 7-position and secondarily by electron-deficient N1-arene at 1-position of benzo[b] [1,8] naphthyridin-4(1H)-one core. The trifluoromethyl at 2-position seems to strength the ICT because it reduced gap energies and increase dipole moments in their derivatives compared to 2-methyl or -hydrogen analogues. Importantly, from the 7-methoxy derivatives, two high photo-stable (15- to 17-fold more than fluorescein) and long-lived (9.75–14.20 ns) fluorophores with acceptable QYs and HOMO-LUMOs were identified. In particular, the fluorophore 3k showed a low cytotoxicity in J774.1A macrophage, pH insensibility and appropriate lipophilicity, which in combination with their good photophysical properties favored the application of the 7-methoxy dyes for bioimaging, giving blue-fluorescent macrophages in relatively short time. Then, the N1-aryl-2-(trifluoromethyl)benzo[b] [1,8] naphthyridin-4(1H)-one by its molecular extension and planarity emerges as an interesting platform to generate long-lived and highly photostable dyes and, the key point is to favor the strength of the internal ICT mechanism through the incorporation of appropriate donor (D) and acceptor (A) groups along the D-A chain.

Visualizing ion channels in lipid nanodomains using live-cell fluorescence lifetime imaging.

Ion channels function in a lipid-membrane nano-environment where the lipid composition and membrane compartmentalization can undergo rapid changes. How transmembrane potential activates voltage-gated ion channels differently in liquid-ordered, cholesterol-rich (Lo, or called “lipid raft”) versus in liquid-disordered, cholesterol-poor membrane (Ld) nanodomains remains less explored in intact cells. Using phasor plot fluorescence-lifetime imaging microscopy (phasor FLIM), combined with Förster resonance energy transfer (FRET) between donor- and acceptor-fluorophores conjugated to cholera toxin subunit B (CTxB) or to short lipidated peptides that specifically recognize Lo and Ld domains, we visualized the membrane domains in different cells, including Xenopus oocytes, cultured primary hepatocytes and dorsal root ganglion (DRG) sensory neurons. We postulate that a large percentage of the plasma membrane could be Lo domain. Extracting cholesterols using β-cyclodextrin was able to decrease the FRET efficiency indicating a reduced size of Lo domains. Interestingly, the measured apparent FRET was low in DRG neurons, consistent with the unique lipid organization of neuronal membranes, in comparison to other cell types. Furthermore, the localization of voltage-gated ion channels in proximity to lipid nanodomains could be examined by either FLIM-FRET or spectral FRET using these fluorescent markers. Moreover, fluorescent noncanonical amino acids (ncAAs) incorporated near the hydrophobic constriction site of voltage sensors of hyperpolarization-activated cyclic nucleotide-gated (HCN) channels showed a similar lifetime as when their free forms were dissolved in hydrophobic solvents; lifetime of the incorporated ncAAs changed upon membrane hyperpolarization. In addition, using the stop-codon suppression strategies and click chemistry via the inverse-electron demand Diels-Alder cycloaddition, a photostable dye was tagged site-specifically to the extracellular region of the HCN voltage sensor. These labeling strategies will facilitate measuring the voltage-sensor conformational dynamics of ion channels in distinct lipid nanodomains using time-resolved phasor FLIM-FRET or single-molecule FRET.

Combined electrical and fluorescence recordings of single molecules in bilayers formed on MECA-opto chips.

Molecular processes within lipid bilayers, such as ion channel insertion and gating, can be followed using electrophysiology techniques. With fluorescently labeled molecules, additional features such as protein aggregation and spatial distribution can also be followed. However, correlated electrical and optical measurements, especially at the single-molecule level, have been historically challenging. Factors such as bilayer stability, the timing of protein aggregation and insertion, and the photostability of fluorescent dyes, all work against successful collection of simultaneous electrical and fluorescence records. Here, we describe approaches for assessing lateral diffusion, single-molecule aggregation, and ion channel insertion in bilayers formed on commercially available micro-electrode cavity arrays (MECA-opto chips). These array chips have been specifically designed to enhance the collection of simultaneous electrical and optical records. We compare lipid and ion-channel diffusion results from both fluorescence correlation spectroscopy and wide-field single-molecule tracking experiments. We also use both approaches to assess protein aggregation, spatial distribution, and correlation with insertion currents in the bilayer.

Long-term photochemical stability of heteroaromatic dye-functionalised g-C3N4via covalent linkage for efficient photocatalytic hydrogen evolution

In this study, three typical D–π–A type heteroaromatic organic dyes containing carbazole (CBZ), phenothiazine (PTZ), and phenoxazine (POZ) moiety as electron donor cores and linked to g-C3N4 with amide covalent bonds were synthesized. Thereafter, we studied the long-term photochemical stability and degradation mechanism of the associated dye-sensitised g-C3N4 with covalent linkage or weak interaction. The results revealed that most of the dyes degraded and became unstable after absorption on g-C3N4 under light irradiation. Interestingly, after the target dyes were linked to g-C3N4 with amide covalent bonds, the photostability could be effectively promoted and improved to high levels of stability. For POZ-S dye covalent bond-linked sample g-C3N4/POZ-S, ∼90.5% percent of the dyes were reserved, whereas only ∼25.3% remained for the physically absorbed dye sample g-C3N4+POZ-S after 30 min of irradiation aging test. Moreover, the obtained g-C3N4/POZ-S sample exhibited enhanced H2 evolution activity with photocatalytic H2 production rates that were approximately 96- fold of that of pure g-C3N4. Then, we applied various instrumental analysis and DFT calculation to clarify the mechanism involved with dye photostability and degradation pathway. The typical decarboxylation process was confirmed, and such an unfavourable reaction process could be effectively inhibited if the target dye is linked to g-C3N4 with amide covalent bond instead of the weak interaction. Overall, the existed covalent bond is the key factor for enhancing both the photochemical stability and photocatalytic activity of organic dye-sensitised g-C3N4 for hydrogen evolution.

Achieving photostability in dye-sensitized upconverting nanoparticles and their use in Fenton type photocatalysis.

Dye sensitization is a promising approach to enhance the luminescence of lanthanide-doped upconverting nanoparticles. However, the poor photostability of near-infrared dyes hampers their use in practical applications. To address this, commercial IR820 was modified for improved photostability and covalently bonded to amine-functionalized silica-coated LnUCNPs. Two methods of covalent linking were investigated: linking the dye to the surface of the silica shell, and embedding the dye within the silica shell. The photostability of the dyes when embedded in the silica shell exhibited upconversion emissions from NaGdF4:Er3+,Yb3+/NaGdF4:Yb3+ nanoparticles for over four hours of continuous excitation with no change in intensity. To highlight this improvement, the photostable dye-embedded system was successfully utilized for Fenton-type photocatalysis, emphasizing its potential for practical applications. Overall, this study presents a facile strategy to circumvent the overlooked limitations associated with photodegradation, opening up new possibilities for the use of dye-sensitized lanthanide-doped upconverting nanoparticles in a range of fields.

An Efficient and Reversible Singlet Oxygen Quencher for Suppressing Photobleaching of Organic Fluorescent Dyes

AbstractQuenching singlet oxygen is the key to improve photostability of fluorescent dyes. We have systematically studied the capability of a new singlet oxygen quencher, DABCOnium (an alkylated derivative of 1,4‐diazabicyclo[2.2.2] octane) on removing singlet oxygen. Results showed that DABCOnium can significantly enhancing photostability of fluorescent thin films for more than 4.3 times compared with that without DABCOnium. After 2 hours of continuous irradiation, fluorescent film doped with DABCOnium retained 90 % of its original fluorescence intensity, which paves a new way in designing high performance singlet oxygen quenchers.

Sterically Shielded Hydrophilic Analogs of Indocyanine Green.

A modular synthetic process enables two or four shielding arms to be appended strategically over the fluorochromes of near-infrared cyanine heptamethine dyes to create hydrophilic analogs of clinically approved indocyanine green. A key synthetic step is the facile substitution of a heptamethine 4'-Cl atom by a phenol bearing two triethylene glycol chains. The lead compound is a heptamethine dye with four shielding arms, and a series of comparative spectroscopy studies showed that the shielding arms (a) increased dye photostability and chemical stability and (b) inhibited dye self-aggregation and association with albumin protein. In mice, the dye cleared from the blood primarily through the renal pathway rather than the biliary pathway for ICG. This change in biodistribution reflects the much smaller hydrodynamic diameter of the shielded hydrophilic ICG analog compared to the 67 kDa size of the ICG/albumin complex. An attractive feature of versatile synthetic chemistry is the capability to systematically alter the dye's hydrodynamic diameter. The sterically shielded hydrophilic ICG dye platform is well-suited for immediate incorporation into dynamic contrast-enhanced (DCE) spectroscopy or imaging protocols using the same cameras and detectors that have been optimized for ICG.

Hybrid of sodium polytungstate polyoxometalate supported by the green substrate for photocatalytic degradation of auramine-O dye.

Nowadays, textile industries have severely polluted the ecosystem and water sources via disposal of highly thermo- and photo-stable dyes within the ecology that require practical strategies to remove them from nature. In studies, the photocatalytic disinfection technique has been shown to have widespread applications in indoor air, environmental health, detection, biological, biomedical, laboratory hospital, pharmaceutical food industry, plant safety, waste water, effluents disposal, and drinking water disinfection. Herein, the sodium polytungstate (SPT) polyoxometalate (POM) was synthesized through a multi-step production procedure and hence modified via employing a green protocol by using tartaric acid, glutamic acid, and kombucha solvent toward efficient and total complete removal of the highly toxic, stable, and carcinogenic auramine-O (AO) dye from aqueous media. In this regard, developed materials were well-characterized, and their photocatalysis performance for photodegradation of AO dye was examined. Achieved results showed that the optimum absorption conditions were achieved at pH of 5.0, 15mg/L of AO concentration, 0.04g of photocatalyst dosage, and 110min irradiation time, where SPT and modified SPT via green protocol showed full desirability (desirability function (DF) index of 1) along with 71.75 and 100% removal percentage, respectively. Obtained results justified the superior photocatalytic role of the SPT POM and its derived nanocluster that can be used for the complete removal of highly stable dyes from aqueous media till reaching the drinking water standard.

Anti-photobleaching cyanine-based nanoparticles with simultaneous PET and ACQ effects for improved tumor photothermal therapy

• Two NIR molecules DTZCy and WTZCy were synthesized for photothermal therapy (PTT). • DTZCy exhibited better PCE (η = 31.8%) due to the intramolecular PET effect. • DTZCy@SiO 2 NPs with intramolecular PET and intermolecular ACQ were prepared. • DTZCy@SiO 2 NPs exhibited high PCE (η = 34.6%) and durable photothermal conversion. • The improved tumor PTT is attributed to the anti-bleaching ability of DTZCy@SiO 2 NPs. To design anti-photobleaching photothermal agents (PTAs) is of great significance for tumor photothermal therapy (PTT). Heptamethine cyanine (Cy7) dyes as one of near-infrared (NIR) PTAs has received extensive attention in PTT. But the poor photostability of Cy7 dyes severely restrict their clinical application. Herein, two new Cy7 dyes DTZCy and WTZCy were prepared, which showed better anti-photobleaching performance than ICG, a commercial Cy7 dye proved by FDA. Noteworthily, the contributions of quenching fluorescence and enhancing photostability to improving the photothermal conversion efficiency (PCE) of Cy7-based PTAs were discussed. DTZCy exhibited much better PCE (η = 31.8%) than WTZCy (η = 16.5%) due to the increased photostability caused by the intramolecular photoinduced electron transfer (PET) effect. Silica nanoparticles encapsulating DTZCy, named as DTZCy@SiO 2 NPs, displayed higher PCE (η = 34.6%) and satisfying photothermal stability both in vitro and vivo, which was attributed to the improved anti-photobleached ability caused by aggregation-caused quenching (ACQ) mechanism. This work may provide new strategies for constructing anti-photobleaching PTAs by simultaneously employing PET and ACQ mechanisms to achieve efficient tumor PTT.