Inflammatory-stimuli-responsive turn-on NIR fluorogenic theranostic prodrug: adjuvant delivery of diclofenac and hydrogen sulfide attenuates acute inflammatory disorders.

Prolonged use of very commonly prescribed non-steroidal anti-inflammatory drugs (NSAIDs) is often associated with undesired side effects, including gastrointestinal ulcers due to the non-selective inhibition of cyclooxygenases. We describe the development of an inflammatory-stimuli-responsive turn-on fluorogenic theranostic prodrug DCF-HS for adjuvant drug delivery. Upon activation by reactive oxygen species (ROS), the prodrug releases diclofenac DCF (active drug) and the NIR fluorophore DCI-NH2 along with carbonyl sulfide (COS). The second activation of COS by the enzyme carbonic anhydrase (CA) generates hydrogen sulfide (H2S). The prodrug was conveniently synthesized using multi-step organic synthesis. The UV-Vis and fluorescence studies revealed the selective reactivity of DCF-HS towards ROS such as H2O2 in the aqueous phase and the desired uncaging of the drug DCF with turn-on NIR fluorescent reporter under physiological conditions. Furthermore, the release of fluorophore DCI-NH2 and drug DCF was confirmed using the reverse phase HPLC method. Compatibility of prodrug activation was studied next in the cellular medium. The prodrug DCF-HS was non-toxic in a representative cancer cell line (HeLa) and a macrophage cell line (RAW 264.7) up to 100 µM concentration, indicating its biocompatibility. The intracellular ROS-mediated activation of the prodrug with the release of NIR dye DCI-NH2 and H2S was investigated in HeLa cells using the H2S-selective probe WSP2. The anti-inflammatory activity of the active drug DCF from the prodrug DCF-HS was studied in the lipopolysaccharide (LPS)-induced macrophage cell line and compared to that of the parent drug DCF using western blot analysis and it was found that the active drug resulted in pronounced inhibition of COX-2 in a dose-dependent manner. Finally, the anti-inflammatory potential of the prodrug and the turn-on fluorescence were validated in the inflammation-induced Wister rat models.

Hydrogen peroxide fluorescent probe-monitored butyric acid inhibition of the ferroptosis process.

Short-chain fatty acids, such as butyrate, play pivotal roles in various physiological processes within the human body. Recent advances in understanding cell death pathways, specifically ferroptosis, have unveiled unique opportunities for therapeutic development. Ferroptosis is linked to iron accumulation and oxidative stress, whereas butyrate has emerged as a cellular protector against oxidative stress, potentially inhibiting ferroptosis. Hydrogen peroxide (H2 O2 ) is a key player in oxidative stress, and its monitoring has gained significance in disease mechanisms. We present an innovative fluorescent probe, HOP, capable of dynamically tracking intracellular H2 O2 levels, enabling spatial and temporal visualization. The probe exhibits high accuracy (limit of detection = 0.14 µM) and sensitivity, paving the way for disease diagnosis and treatment innovations. Importantly, HOP displayed minimal toxicity, making it suitable for cellular applications. Cellular imaging experiments demonstrated its ability to penetrate cells and monitor intracellular H2 O2 levels accurately. The HOP probe confirmed H2 O2 as a critical marker in ferroptosis. Our innovative HOP provides a powerful tool for tracking intracellular H2 O2 levels and offers insights into the modulation of ferroptosis, potentially opening new avenues for disease research and therapeutic interventions.

Discovery of RORγ Allosteric Fluorescent Probes and Their Application: Fluorescence Polarization, Screening, and Bioimaging.

Retinoic acid receptor-related orphan receptor γ (RORγ) acts as a crucial transcription factor in Th17 cells and is involved in diverse autoimmune disorders. RORγ allosteric inhibitors have gained significant research focus as a novel strategy to inhibit RORγ transcriptional activity. Leveraging the high affinity and selectivity of RORγ allosteric inhibitor MRL-871 (1), this study presents the design, synthesis, and characterization of 11 allosteric fluorescent probes. Utilizing the preferred probe 12h, we established an efficient and cost-effective fluorescence polarization-based affinity assay for screening RORγ allosteric binders. By employing virtual screening in conjunction with this assay, 10 novel RORγ allosteric inhibitors were identified. The initial SAR studies focusing on the hit compound G381-0087 are also presented. The encouraging outcomes indicate that probe 12h possesses the potential to function as a powerful tool in facilitating the exploration of RORγ allosteric inhibitors and furthering understanding of RORγ function.

Bimodal effects on lipid droplets induced in cancer and non-cancer cells by chemotherapy drugs as revealed with a green-emitting BODIPY fluorescent probe.

Lipid droplets (LDs) are cytoplasmic lipid-rich organelles with important roles in lipid storage and metabolism, cell signaling and membrane biosynthesis. Additionally, multiple diseases, such as obesity, fatty liver, cardiovascular diseases and cancer, are related to the metabolic disorders of LDs. In various cancer cells, LD accumulation is associated with resistance to cell death, reduced effectiveness of chemotherapeutic drugs, and increased proliferation and aggressiveness. In this work, we present a new viscosity-sensitive, green-emitting BODIPY probe capable of distinguishing between ordered and disordered lipid phases and selectively internalising into LDs of live cells. Through the use of fluorescence lifetime imaging microscopy (FLIM), we demonstrate that LDs in live cancer (A549) and non-cancer (HEK 293T) cells have vastly different microviscosities. Additionally, we quantify the microviscosity changes in LDs under the influence of DNA-damaging chemotherapy drugs doxorubicin and etoposide. Finally, we show that doxorubicin and etoposide have different effects on the microviscosities of LDs in chemotherapy-resistant A549 cancer cells.

Fluorescent probes and degraders of the sterol transport protein Aster-A.

Our understanding of sterol transport proteins (STPs) has increased exponentially in the last decades with advances in the cellular and structural biology of these important proteins. However, small molecule probes have only recently been developed for a few selected STPs. Here we describe the synthesis and evaluation of potential proteolysis-targeting chimeras (PROTACs) based on inhibitors of the STP Aster-A. Based on the reported Aster-A inhibitor autogramin-2, ten PROTACs were synthesized. Pomalidomide-based PROTACs functioned as fluorescent probes due to the intrinsic fluorescent properties of the aminophthalimide core, which in some cases was significantly enhanced upon Aster-A binding. Most PROTACs maintained excellent binary affinity to Aster-A, and one compound, NGF3, showed promising Aster-A degradation in cells. The tools developed here lay the foundation for optimizing Aster-A fluorescent probes and degraders and studying its activity and function in vitro and in cells.

Construction of a New Probe Based on Copper Chaperone Protein for Detecting Cu2+ in Cells.

Biomacromolecular probes have been extensively employed in the detection of metal ions for their prominent biocompatibility, water solubility, high selectivity, and easy modification of fluorescent groups. In this study, a fluorescent probe FP was constructed. The probe FP exhibited high specificity recognition for Cu2+. With the combination of Cu2+, the probe was subjected to fluorescence quenching. The research suggested that the probe FP carried out the highly sensitive detection of Cu2+ with detection limits of 1.7 nM. The fluorescence quenching of fluorescamine was induced by Cu2+ perhaps due to the PET (photoinduced electron transfer) mechanism. The FP-Cu2+ complex shows weak fluorescence, which is likely due to the PET quenching effect from Cu2+ to fluorescamine fluorophore. Moreover, the probe FP can be employed for imaging Cu2+ in living cells. The new fluorescent probe developed in this study shows the advantages of good biocompatibility and low cytotoxicity. It can be adopted for the targeted detection of Cu2+ in cells, and it has promising applications in the mechanism research and diagnosis of Cu2+-associated diseases.

Novel estrogen receptor ß/histone deacetylase dual-targeted near-infrared fluorescent probes as theranostic agents for imaging and treatment of prostate cancer.

Estrogen receptor (ER) ß and histone deacetylases (HDACs), when overexpressed, are associated closely with the occurrence and development of prostate cancer and are, therefore, considered important targets and biomarkers used in the clinical treatment of prostate cancer. The present study involved the design and synthesis of the first ERß and HDAC dual-target near-infrared fluorescent probe with both imaging capacity and antitumor activity for prostate cancer. Both P1 and P2 probes exhibited excellent ERß selectivity, with P1 being almost exclusively selective for ERß compared to ERα. In addition, P1 exhibited good optical properties, such as strong near-infrared emission, large Stokes shift, and better anti-interference ability, along with excellent imaging ability for living cells. P1 also exhibited potent inhibitory activity against HDAC6 and DU-145 cells, with IC50 values of 52 nM and 0.96 µM, respectively. Further, P1 was applied successfully for the in vivo imaging of prostate cancer in a mouse model, and significant in vivo antitumor efficacy was achieved. The developed dual-target NIR fluorescent probe is expected to serve as an effective tool in the research on prostate cancer, leading to novel insights for the theranostic study of diseases related to ERß and HDACs.

Ginseng root extract-mediated synthesis of monodisperse silver nanoparticles as a fluorescent probe for the spectrofluorometric determination of nilvadipine; Evaluation of remarkable anti-bacterial, anti-fungal and in-vitro cytotoxic activities.

Nanoparticles are a boon for humanity because of their improved functionality and unlimited potential applications. Considering this significance, the proposed study introduced a simple, fast and eco-friendly method for synthesis of fluorescent silver nanoparticles (Ag-NPs) using Panax Ginseng root extract as a reducing and capping agent. Synthesis of Ag-NPs was performed in one step within three minutes utilizing microwave irradiation. The resulting Ag-NPs were characterized using various microscopic and spectroscopic techniques such as, Transmission Electron Microscope (TEM), UV/Visible spectroscopy, Fourier Transform Infrared Spectroscopy(FTIR) and Energy Dispersive X-ray analysis (EDX). The prepared Ag-NPs, which act as a fluorescent nano-probe with an emission band at 416 nm after excitation at 331 nm, were used to assay nilvadipine (NLV) spectrofluorimetrically in its pharmaceutical dosage form with good sensitivity and reproducibility. The proposed study is based on the ability of NLV to quantitatively quench the native Ag-NPs fluorescence, forming a ground state complex as a result of static quenching and an inner filter mechanism. The suggested approach displayed a satisfactory linear relationship throughout a concentration range of 5.0 µM - 100.0 µM, with LOD and LOQ values of 1.18 µM and 3.57 µM, respectively. Validation of the suggested approach was examined in accordance with ICH recommendations. In addition, the anti-bacterial and anti-fungal activities of the prepared nanoparticles were investigated, and they demonstrated effective anti-microbial activities and opened a future prospective to combat future antibiotic resistance. Finally, in-vitro cytotoxicity assay of Ag-NPs against normal and cancerous human cell lines was studied using MTT assay. The results proved the potential use of the produced Ag-NPs as an adjunct to anticancer treatment or for drug delivery without significantly harming healthy human cells.

A novel NIR fluorescent probe inhibits melanoma progression through apoptosis and ERK/DRP1-mediated mitochondrial fission.

Melanoma, a highly metastatic malignant tumour, necessitated early detection and intervention. This study focuses on a hemicyanine fluorescent probe activated by near-infrared (NIR) light for bioimaging and targeted mitochondrial action in melanoma cells. IR-418, our newly designed hemicyanine-based NIR fluorescent probe, demonstrated effective targeting of melanoma cell mitochondria for NIR imaging. In vitro and in vivo experiments revealed IR-418's inhibition of melanoma growth through the promotion of mitochondrial apoptosis (Bax/Bcl-2/Cleaved Caspase pathway). Moreover, IR-418 inhibited melanoma metastasis by inhibiting mitochondrial fission through the ERK/DRP1 pathway. Notably, IR-418 mitigated abnormal ATL and ASL elevations caused by tumours without inflicting significant organ damage, indicating its high biocompatibility. In conclusion, IR-418, a novel hemicyanine-based NIR fluorescent probe targeting the mitochondria, exhibits significant fluorescence imaging capability, anti-melanoma proliferation, anti-melanoma lung metastasis activities and high biosafety. Therefore, it has significant potential in the early diagnosis and treatment of melanoma.

Counterion influence on near-infrared-II heptamethine cyanine salts for photothermal therapy.

Photothermal therapy (PTT) has attracted extensive attention in cancer treatment. Heptamethine cyanine dyes with near-infrared (NIR) absorption performance have been investigated for PTT. However, they are often accompanied by poor photostability, suboptimal photothermal conversion and limited therapeutic efficacy. The photophysical properties of fluorescent organic salts can be tuned through counterion pairing. However, whether the counterion can influence the photostability and photothermal properties of heptamethine cyanine salts has not been clarified. In this work, we investigated the effects of eleven counter anions on the physical and photothermal properties of NIR-II heptamethine cyanine salts with the same heptamethine cyanine cation. The anions have great impacts on the physiochemical properties of dyes in solution including aggregation, photostability and photothermal conversion efficiency. The physical tuning enables the control over the cytotoxicity and phototoxicity of the dyes. The selected salts have been demonstrated to significantly suppress 4T1 breast tumor growth with low toxicity. The findings that the counterion has great effects on the photothermal properties of cationic NIR-II heptamethine cyanine dyes will provide a reference for the preparation of improved photothermal agents through counterion pairing with possible translation to humans.

Polymer Nanoparticles with 2-HP-ß-Cyclodextrin for Enhanced Retention of Uptake into HCE-T Cells.

Triamcinolone acetonide (TA), a medium-potency synthetic glucocorticoid, is primarily employed to treat posterior ocular diseases using vitreous injection. This study aimed to design novel ocular nanoformulation drug delivery systems using PLGA carriers to overcome the ocular drug delivery barrier and facilitate effective delivery into the ocular tissues after topical administration. The surface of the PLGA nanodelivery system was made hydrophilic (2-HP-ß-CD) through an emulsified solvent volatilization method, followed by system characterization. The mechanism of cellular uptake across the corneal epithelial cell barrier used rhodamine B (Rh-B) to prepare fluorescent probes for delivery systems. The triamcinolone acetonide (TA)-loaded nanodelivery system was validated by in vitro release behavior, isolated corneal permeability, and in vivo atrial hydrodynamics. The results indicated that the fluorescent probes, viz., the Rh-B-(2-HP-ß-CD)/PLGA NPs and the drug-loaded TA-(2-HP-ß-CD)/PLGA NPs, were within 200 nm in size. Moreover, the system was homogeneous and stable. The in vitro transport mechanism across the epithelial barrier showed that the uptake of nanoparticles was time-dependent and that NPs were actively transported across the epithelial barrier. The in vitro release behavior of the TA-loaded nanodelivery systems revealed that (2-HP-ß-CD)/PLGA nanoparticles could prolong the drug release time to up to three times longer than the suspensions. The isolated corneal permeability demonstrated that TA-(2-HP-ß-CD)/PLGA NPs could extend the precorneal retention time and boost corneal permeability. Thus, they increased the cumulative release per unit area 7.99-fold at 8 h compared to the suspension. The pharmacokinetics within the aqueous humor showed that (2-HP-ß-CD)/PLGA nanoparticles could elevate the bioavailability of the drug, and its Cmax was 51.91 times higher than that of the triamcinolone acetonide aqueous solution. Therefore, (2-HP-ß-CD)/PLGA NPs can potentially elevate transmembrane uptake, promote corneal permeability, and improve the bioavailability of drugs inside the aqueous humor. This study provides a foundation for future research on transocular barrier nanoformulations for non-invasive drug delivery.

One-step synthesis of a dual-functional AIE-active probe for ClO- detection and photodynamic therapy.

An amphiphilic fluorescent probe (BHSMP) with aggregation-induced emission (AIE) features was synthesized via a one-step route. The probe showed high water dispersibility, low toxicity and the ability of selective and sensitive (limit of detection of 0.11 µM) detection of ClO- with fast-response (≤30 s) in aqueous solution and living organisms. Owing to the donor-acceptor (D-A) structure and existence of cationic groups, BHSMP could also generate reactive oxygen species under light-irradiation and potentially be utilized for photodynamic therapy. The strategy described in this work is of great significance for the design and synthesis of multifunctional AIE-active functional materials to facilitate their biomedical applications.

Azide-modified corrole phosphorus complexes for endoplasmic reticulum-targeted fluorescence bioimaging and effective cancer photodynamic therapy.

Study on corrole photosensitizers (PSs) for photodynamic therapy (PDT) has made remarkable progress. Targeted delivery of PSs is of great significance for enhancing therapeutic efficiency, decreasing the dosage, and reducing systemic toxicity during PDT. The development of PSs that can be specifically delivered to the subcellular organelle is still an attractive and challenging work. Herein, we synthesize a series of azide-modified corrole phosphorus and gallium complex PSs, in which phosphorus corrole 2-P could not only precisely target the endoplasmic reticulum (ER) with a Pearson correlation coefficient (PCC) up to 0.92 but also possesses the highest singlet oxygen quantum yields (ΦΔ = 0.75). This renders it remarkable PDT activity at a very low dosage (IC50 = 23 nM) towards HepG2 tumor cell line while ablating solid tumors in vivo with excellent biosecurity. Furthermore, 2-P exhibits intense red fluorescence (ΦF = 0.25), outstanding photostability, and a large Stokes shift (190 nm), making it a promising fluorescent probe for ER. This study provides a clinically potential photosensitizer for cancer photodynamic therapy and a promising ER fluorescent probe for bioimaging.

A novel fluorescent probe based on carbazole-thiophene for the recognition of hypochlorite and its applications.

A carbazole thiophene-aldehyde and 4-methylbenzenesulfonhydrazide conjugate CSH was synthesized by introducing 5-thiophene aldehyde at the 3-position of the carbazole group as the precursor and then condensing it with 4-methylbenzenesulfonhydrazide. CSH has high selectivity and sensitivity towards ClO-, which can specifically identify ClO- by UV-Vis and fluorescence spectroscopy. CSH can rapidly respond to ClO- in the physiological pH range through a fluorescence quenching pattern, accompanied by the color of CSH changing markedly from turquoise to yellowish green under the 365 nm UV light. Probe CSH exhibits a quantitative response to ClO- (0-11 µM) with a low detection limit (1.16 × 10-6 M). Cell imaging experiments have shown that CSH can capture fluorescent signals in the cyan and yellow channels of HeLa cells through fluorescence confocal microscopy, and can successfully identify exogenous ClO- in HeLa cells. In addition, probe CSH can also be used to detect ClO- in environmental water samples. These results indicate that CSH has potential application prospects in the environmental analysis and biological aspects.

De Novo Design of Near-Infrared Fluorescent Agents Activated by Peroxynitrite and Glutathione-Responsive Imaging for Diabetic Liver Disease.

Diabetes and its complications, such as diabetes liver disease, is a major problem puzzling people's health. The detection of redox states in its pathological process can effectively help us gain a deeper understanding of the disease. The pair of oxidation-reduction substances peroxynitrite (ONOO- ) and glutathione (GSH) is considered to be closely related to their occurrence and development. Thus, direct visualization of ONOO- and GSH in diabetes liver disease is critical to evaluate the disease at the molecular level. Herein, two activatable agents NTCF-ONOO- and NTCF-GSH are prepared for selectively detecting ONOO- and GSH through protection and deprotection strategies based on hydroxyl and amino groups of near-infrared fluorophore. Fluorescence imaging of exogenous and endogenous ONOO- and GSH changes in living cells and in vivo is observed. The ONOO- and GSH level in the diabetes liver disease cellular model are visualized and the possible redox imbalance mechanism related to the oxidized (NAD+ ) and reduced (NADH) nicotinamide adenine dinucleotides is explored in this process. Moreover, these probes can sensitively recognize ONOO- and GSH in the process of oxidative stress resulting from streptozotocin and streptozotocin/acetaminophen-induced complex diabetic liver disease in vivo. In addition, they can be applied for monitoring the clinical serum sample related with diabetic patients.

Thiophene π-bridge-based second near-infrared luminogens with aggregation-induced emission for biomedical applications.

In the past 5 years, aggregation-induced emission luminogens (AIEgens) with emission in the second near-infrared (NIR-II) optical window have aroused great interest in bioimaging and disease phototheranostics, benefiting from the merits of deep penetration depth, reduced light scatting, high spatial resolution, and minimal photodamage. To construct NIR-II AIEgens, thiophene derivatives are frequently adopted as π-bridge by virtue of their electron-rich feature and good modifiability. Herein, we summarize the recent progress of NIR-II AIEgens by employing thiophene derivatives as π-bridge mainly compassing unsubstituted thiophene, alkyl thiophene, 3,4-ethylenedioxythiophene, and benzo[c]thiophene, with a discussion on their structure-property relationships and biomedical applications. Finally, a brief conclusion and perspective on this fascinating area are offered.

Visualization of production and remediation of acetaminophen-induced liver injury by a carboxylesterase-2 enzyme-activatable near-infrared fluorescent probe.

Acetaminophen (APAP) overdose, also known as APAP poisoning, may directly result in hepatic injury, acute liver failure and even death. Nowadays, APAP-induced liver injury (AILI) has become an urgent public health issue in the developing world so the early accurate diagnosis and the revelation of underlying molecular mechanism of AILI are of great significance. As a major detoxifying organ, liver is responsible for metabolizing chemical substances, in which human carboxylesterase-2 (CES2) is present. Hence, we chose CES2 as an effective biomarker for evaluating AILI. By developing a CES2-activatable and water-soluble fluorescent probe PFQ-E with superior affinity (Km = 5.9 µM), great sensitivity (limit of detection = 1.05 ng/mL), near-infrared emission (655 nm) and large Stokes shift (135 nm), activity and distribution of CES2 in cells were determined or imaged effectively. More importantly, the APAP-induced hepatotoxicity and the underlying molecular mechanism of pathogenesis of AILI were investigated by measuring the "light-up" response of PFQ-E towards endogenous CES2 in vivo for the first time. Based on the superior performance of the probe PFQ-E for sensing CES2, we believe that it has broad potential in clinical diagnosis and therapy response evaluation of AILI.

A single mitochondria-targetable fluorescent probe for visualizing cysteine and glutathione in ferroptosis of myocardial ischemia/reperfusion injury.

Ferroptosis plays an important role in the early stage of myocardial ischemia/reperfusion (MI/R) injury, which is closely associated with the antioxidant damage of mitochondrial cysteine (Cys)/glutathione (GSH)/glutathione peroxidase 4 (GPX4) axis. Visualization of Cys and GSH in mitochondria is meaningful to value ferroptosis and further contributes to understanding and preventing MI/R injury. Herein a mitochondria-targetable thiols fluorescent probe (MTTP) was designed and synthesized based on sulfonyl benzoxadiazole (SBD) chromophore with a triphenylphosphine unit as the mitochondria-targeted functional group. Cys and GSH can be differentiated by MTTP with two distinguishable emission bands (583 nm and 520 nm) through the controllable aromatic substitution-rearrangement reaction. Importantly, MTTP is capable of monitoring ferroptosis and its inhibition by measuring mitochondrial Cys and GSH. MTTP was also employed to non-invasively detect ferroptosis during oxygen and glucose deprivation/reoxygenation (OGD/R)-induced MI/R injury in H9C2 cells. In a word, MTTP provides a visual tool that can simultaneously detect Cys and GSH to monitor ferroptosis processes during MI/R injury, which helps for more deeper understanding of the role of ferroptosis in MI/R injury-related diseases.

Development of an activatable Lysosome-targeted fluorescent probe for the detection of endogenous ONOO- levels.

The liver plays a crucial role in several important processes in the human body, including metabolism, detoxification, and immune function. When the liver experiences acute injury, it can cause significant harm and requires prompt detection. Traditional biomarkers lack specificity and cannot detect changes in real-time, making them unsuitable for monitoring pathological processes. Recent studies have shown that acute liver injury (ALI) is closely related to oxidative stress, with peroxynitrite (ONOO-) being a vital byproduct of liver metabolism and become a critical biomarker for detecting liver damage. As a result, this research developed an activatable near-infrared fluorescent probe W-3a that can be used to detect endogenous ONOO- in a mouse model of ALI induced by lipopolysaccharides (LPS). The probe has high selectivity and anti-interference ability, with a reaction time <10 min and a detection limit of 85 nM. It was successfully utilized in detecting endogenous ONOO- in cells and live imaging of ALI mice.

CO2-Responsive Water-Soluble Conjugated Polymers as a Multifunctional Fluorescent Probe for Bioimaging Applications.

We describe important progress in the synthesis and development of gas-responsive water-soluble conjugated polymers (WSCPs) with potential as multifunctional fluorescent materials for biomedical imaging and probes. A water-soluble WSCP (I-PT) composed of a hydrophobic fluorescent polythiophene backbone and a hydrophilic imidazole side chain was successfully prepared through a facile and efficient two-step synthetic route. Owing to the repulsive force between the hydrophilic and hydrophobic segments and the highly sensitive carbon dioxide (CO2)- and nitrogen (N2)-responsive imidazole groups in its structure, I-PT can spontaneously self-assemble into spherical-like nanoparticles in an aqueous environment, and thus exhibits unique light absorption and fluorescence properties as well as rapid responsiveness to CO2 and N2. In addition, its structure, optical absorption/fluorescence behavior, and surface potential can be quickly turned on and off through alternating cycles of CO2 and N2 bubbling and exhibit controllable cyclic switching stability, thereby allowing effective manipulation of its hierarchical structure and chemical-physical characteristics. More importantly, a series of in vitro cell experiments confirmed that, compared to the significant cytotoxicity of pristine and N2-treated I-PT nanoparticles, CO2-treated I-PT nanoparticles exhibit extremely low cytotoxicity in normal and cancer cells and undergo greatly accelerated cellular uptake, resulting in a significant increase in the intensity and stability of their fluorescence signal in the intracellular environment. Overall, this newly discovered CO2/N2-responsive system provides new insights to effectively enhance the biocompatibility, cellular internalization, and intracellular fluorescence characteristics of WSCPs and holds great potential for biomedical imaging/sensing applications.