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Background: Prediction of resistance mechanisms for epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) remains challenging. Thus, we investigated whether resistant cancer cells that expand shortly after EGFR-TKI treatment would eventually cause the resistant phenotype. Methods: We generated two EGFR-mutant lung cancer cell lines resistant to gefitinib (PC9GR and HCC827GR). The parent cell lines were exposed to short-term treatment with gefitinib or paclitaxel and then were assessed for EGFR T790M mutation and C-MET expression. These experiments were repeated in vivo and in clinically relevant patient-derived cell (PDC) models. For validation in clinical cases, we measured these gene alterations in plasma circulating tumor DNA (ctDNA) before and 8 weeks after starting EGFR-TKIs in four patients with EGFR-mutant lung cancer. Results: T790M mutation was only detected in the PC9GR cells, whereas C-MET amplification was detected in the HCC827GR cells. The T790M mutation level significantly increased in PC9 cells after short-term treatment with gefitinib but not in the paclitaxel. C-MET mRNA expression was only significantly increased in gefitinib-treated HCC827 cells. We confirmed that the C-MET copy number in HCC827 cells that survived after short-term gefitinib treatment was significantly higher than that in dead HCC827 cells. These findings were reproduced in the in vivo and PDC models. An early on-treatment increase in the plasma ctDNA level of these gene alterations was correlated with the corresponding resistance mechanism to EGFR-TKIs, a finding that was confirmed in post-treatment tumor tissues. Conclusions: Early on-treatment kinetics in resistance-related gene alterations may predict the final mechanism of EGFR-TKI resistance.

Unlike conventional 1H magnetic resonance imaging (MRI), 19F MRI features unambiguous detection of fluorine spins due to negligible background signals. Therefore, it is considered a promising noninvasive and selective imaging method for the diagnosis of cancers and other diseases. For 19F MRI, fluorine-rich molecules such as perfluorocarbons (PFC) have been formulated into nanoemulsions and used as its tracer agent. Along with advancements in other types of nanoparticles as targeted theranostics and stimuli-triggered probes and combined with the advantages of 19F MRI, PFC nanoemulsions are being empowered with these additional functionalities and becoming a promising theranostic platform. In this Review, we provide an overview of fluorine-based materials for sensitive 19F MRI of biological and pathological conditions. In particular, we describe designs and applications of recently reported stimuli-responsive and theranostic 19F MRI probes. Finally, challenges and future perspectives regarding the further development of 19F MRI probes for their clinical applications are described.

We report a photoactivatable fluorophore that relies on the conversion of a dark meso-ester-BODIPY to an emissive meso-carboxylate-BODIPY. The process is triggered by the photolysis of an aryl azid...

With the development of advanced and minimally invasive surgical techniques, and in view of the functional and cosmetic aspects, the need for rapid and accurate diagnosis during surgery is increasing. This study was conducted to develop a tissue diagnosis method using confocal microscopy after simple tissue staining that does not require freezing and slicing. At present, fluorescence staining with confocal microscopy is not generalized for real-time diagnosis during surgery. In this paper, we propose a fluorescence staining method using Hoechst 33342 and Eosin that does not require tissue freezing and slicing. The proposed method can be used as part of a rapid tissue diagnosis method that is suitable for use in the operating room, although further research is required before it can be applied in clinical practice.

Epidermal growth factor receptor (EGFR) is overexpressed in many types of cancers, which is associated with metastatic potential and poor prognosis in cancer patients. Therefore, development of EGFR-targeted sensitive imaging probes has been a challenge in tumor targeting, image-guided cancer surgery, patient-selective anti-EGFR therapy, and efficient targeted therapies. Methods: We synthesized a zwitterionic near-infrared fluorophore (ATTO655)-conjugated epidermal growth factor (EGF) as a novel activatable molecular probe. Fluorescence OFF/ON property and EGFR-targeting specificity of EGF-ATTO655 as well as its utility in real-time near-infrared (NIR) fluorescence imaging of EGFR-positive cancers were evaluated using in vitro and in vivo studies. Results: When conjugated to EGF, the fluorescence of ATTO655 quenched efficiently by photo-induced electron transfer (PET) mechanism between the conjugated dyes and nearby amino acid quenchers (tryptophan/tyrosine residues), which was stably maintained at physiological pH and in the presence of serum for at least 17 h. The fluorescence of EGF-ATTO655 turned on by receptor-mediated endocytosis and subsequent disintegration of EGF in EGFR-positive A431 cancer cells, thereby enabling specific and real-time fluorescence imaging of EGFR-positive cancer cells. Consequently, EGFR-positive tumors could be clearly visualized 3 h post-injection with a significantly high tumor-to-background ratio (TBR = 6.37). Conclusion: This PET mechanism-based OFF/ON type of EGF probe showed great potential for rapid, real-time, and target-cell-specific imaging of EGFR-overexpressing cancers in vitro and in vivo.

Successful applications of photodynamic therapy (PDT) in cancer treatment require the development of effective photosensitizers with controllable singlet oxygen generation. Here we report a ubiquinone-BODIPY photosensitizer that self-assembles into nanoparticles (PS-Q-NPs) and undergoes selective activation and deaggregation within the highly reductive intracellular environment of tumor cells. PS-Q-NPs are highly stable in aqueous buffer solution, and exhibit minimal fluorescence and photosensitization due to a rapid non-radiative relaxation process. Upon endocytosis by cancer cells, reduction of the ubiquinone moiety by intracellular glutathione (GSH) triggers the conversion of the aggregated hydrophobic precursor into the active hydrophilic carboxylate derivative PS-A. The conversion results in enhanced fluorescence and therapeutic singlet oxygen generation, portending to its application as an activatable photosensitizer for fluorescence imaging-guided photodynamic cancer therapy.

In article number 2002988, Yongdoo Choi, Hyonchol Jang, and co‐workers developed a quenched annexin V‐near‐infrared (NIR) fluorophore conjugate (Q‐annexin V) as the first OFF‐ON‐type NIR fluorescence probe for real‐time apoptosis imaging. The NIR fluorescence of Q‐annexin V is quenched in the extracellular region but can be selectively turned on upon binding to apoptotic cells, thereby enabling the real‐time monitoring of dynamic and topological apoptosis in 2D and 3D cell‐culture systems. Its potential utility in vivo was also confirmed in animal models of cisplatin‐induced acute kidney injury and cancer immunotherapy. [Image: see text]

Cetuximab–dye conjugates have shown great potential for image-guided surgery of epidermal growth factor receptor (EGFR)-positive cancers in clinical trials. However, their long circulation half-life and prolonged generation of high background signals require the injection of antibody conjugates several days prior to imaging, which limits the clinical applications. Herein, we developed a cetuximab–ATTO655 conjugate (i.e., Q-Cetuximab) for fast and real-time fluorescence imaging of EGFR-positive lung cancers. The fluorescence intensity of Q-Cetuximab was quenched to just 6.9% of that of the unconjugated dye when only 2.14 ATTO655 dyes were conjugated to cetuximab. In vitro real-time cell imaging showed that EGFR-positive A549 cells emitted strong fluorescence at 10 min after Q-Cetuximab treatment in the absence of the washing step, implying target-specific activation of quenched Q-Cetuximab fluorescence upon binding with EGFR-positive cancer cells. When mice with orthotropic A549 tumors received intravenous injection of Q-Cetuximab, scattered microsized tumors in the lungs could be clearly identified from near-infrared fluorescence imaging with a tumor-to-background ratio of 4.28 at 8 h post-injection. For comparison, the cetuximab–Alexa647 conjugate (i.e., ON-Cetuximab), which does not show fluorescence quenching, was synthesized as an always-on type of probe. The ON-Cetuximab-treated mice expressed strong fluorescence throughout their body at 8 h post-injection; therefore, lung tumor sites could not be discriminated using fluorescence imaging. These results confirm the benefits of Q-Cetuximab for image-guided precision surgery of EGFR-positive lung cancers.

Radiotherapy (RT) is a major modality for cancer treatment, along with surgery and chemotherapy. Despite its therapeutic effect, the recurrence and metastasis of tumors due to the acquired resistance of cancer cells to RT remain significant clinical problems. Therefore, it is imperative to overcome radioresistance and improve radiosensitivity in cancer patients. Here, we synthesized hydroxychloroquine (HCQ)-loaded hollow mesoporous silica nanoparticles (HMSNs) to enable effective inhibition of radiation-induced cytoprotective autophagy and enhance the therapeutic efficacy of RT. HCQ-HMSN-treated HCT116 colon cancer cells showed a 200-fold higher intracellular uptake of HCQ than that of free HCQ-treated cells, thereby effectively inhibiting the radiation-induced autophagy of cancer cells. In vivo imaging and therapy studies of a tumor xenograft model showed preferential accumulation of HCQ-HMSNs in tumor tissues and significant enhancement of RT by inhibiting autophagy in the tumor sites. Histopathology analyses of major organs, blood chemistry profiles, and changes in body weights of mice confirmed the good biocompatibility of HCQ-HMSNs.

Photosensitizers conjugated with hyaluronic acid via disulfide linkers were developed for biologically activatable near-infrared fluorescence imaging and photodynamic therapy. The nanoparticles prepared from the conjugate are nonfluorescent and nonphototoxic in their native state, but become highly fluorescent and phototoxic in response to reductive agents inside cancer cells.

Here, we propose a zwitterionic near-infrared (NIR) fluorophore-tryptophan (Trp) conjugate with a cleavable linker as a minimal-sized versatile platform (MP) for the preparation of peptide ligand-based off-on type molecular probes. The zwitterionic NIR fluorophore in MP undergoes fluorescence quenching via a photoinduced electron transfer mechanism when in close proximity to tryptophan, and nonspecific binding with serum proteins is minimized by the zwitterionicity of the fluorophore. The linker can be cleaved inside cancer cells in response to tumor-associated stimuli. As a proof-of-concept experiment, ATTO655 was covalently linked with Trp via a diarginine linker to form an MP. A cyclic peptide consisting of Arg-Gly-Asp-d-Phe-Lys (cRGD) was used as a cancer-targeting ligand and was conjugated to the MP to form cRGD-MP. The NIR fluorescence of cRGD-MP could be selectively turned on inside the target cancer cells, thereby enabling specific fluorescence imaging of integrin αvβ3-overexpressing cancer cells in vitro and in vivo.

Background Simplified hematoxylin and eosin (H&E) staining followed by cryo-sectioning enables rapid identification of cancerous tissue within the procedure room during Mohs micrographic surgery. Yet, a faster evaluation method is desirable as the staining protocol requires physically sectioning of the tissue after freezing, which leads to prolonged sectioning time along with the frozen artifacts that may occur in frozen sectioning. Methods We present a multichannel confocal microscopy system to rapidly evaluate cancerous tissue. Using the optical sectioning capability of the confocal microscope, optically sectioned images of the freshly excised mouse tissue were acquired and converted into images resembling H&E histology. To show details of the nuclei and structure of the tissue, we applied a newly developed rapid tissue staining method using Hoechst 33342 and Eosin-Y. Line scanning and stitching was performed to overcome the limited field of view of the confocal microscope. Unlike previous confocal systems requiring an additional mechanical device to tilt the sample and match the focus of the objective lens, we developed a focus tracking method to rapidly scan large sample area. The focus tracking provides an effective means of keeping the image of the thick tissue in focus without additional devices. We then evaluated the performance of the confocal microscope to obtain optically sectioned images in thick tissue by comparing fluorescence stained slide images. We also obtained the corresponding H&E histology image to assess the potential of the system as a diagnostic tool. Results We successfully imaged freshly excised mouse organs including stomach, tumor, and heart within a few minutes using the developed multichannel confocal microscopy and the tissue staining method. Using the pseudocolor method, colors of the acquired confocal grayscale images are converted to furthermore resemble Hematoxylin and Eosin histology. Due to the focus tracking and the line scanning, optically sectioned images were obtained over the large field of view. Comparisons with H&E histology have shown that the confocal images can acquire large details such as the ventricle as well as small details such as muscle fibers and nuclei. Conclusions This study confirms the use of confocal fluorescence microscopy technique to acquire rapid pathology results using optical sectioning, line scanning and focus tracking. We anticipate that the presented method will enable intraoperative histology and significantly reduce stress on patients undergoing surgery requiring repeated histology examinations.

Background: Atherosclerosis is a major global health concern. Targeting macrophages is hypothesized as an alternative treatment for atherosclerosis. Methods: We synthesized alginate-based cisplatin-loaded nanogels (TANgel) as a pH-responsive drug-releasing theranostic nanoplatform for macrophage cells. Carboxylic acid groups of alginic acid were modified with iminodiacetic acid (IDA) to enhance chelation of platinum ions. The near infrared (NIR) fluorophore ATTO655 was conjugated to the modified alginic acid. Cisplatin was used as an antiproliferation drug and as a crosslinking agent between alginate molecules to form TANgel. Release behavior of cisplatin from TANgel was analyzed under different pH conditions. Cellular uptake and therapeutic efficacy of TANgel were tested in the macrophage cell line J774A.1 and normal human cell lines such as HDMVECn. Results: The nanogel had a narrow size distribution of approximately 100 nm. The nanogel showed highly pH-responsive drug release behavior. All incorporated cisplatin was released at pH 5 within 48 h, while less than 15% was released at pH 7.4. The nanogel was preferentially taken up by J774A.1 cells compared to normal human cells, enabling selective NIR fluorescence imaging and chemotherapy of macrophage cells. In addition, the nanogel formulation lowered the therapeutic concentration of the drug with and without low dose radiation therapy (RT) compared to the free drug form. Conclusions: This nanogel system may have potential utility for selective NIR fluorescence imaging and combined chemo/radio therapy of proliferating macrophage cells in atherosclerotic regions, allowing for reduction of systemic toxicity.

Here we have developed a redox-responsive folate-fluorophore conjugate (RFC) with a disulfide linker for the target-specific imaging of cancers. The quenched fluorescence of the RFC could be turned on after folate receptor-mediated endocytosis and subsequent cleavage of the disulfide linker by intracellular glutathione, enabling target-cell-specific fluorescence imaging with a high target-to-background ratio.

We report the p-nitrobenzyl ester of a meso-carboxyl BODIPY as a new fluorogenic probe for the monitoring of nitroreductase activity. It showed remarkable fluorescence enhancement (∼220-fold), high sensitivity (detection limit of 0.9 ng/mL), and high selectivity for nitroreductase over other bio-related species. In vitro cell studies confirmed its utility for the rapid fluorescence imaging of hypoxic cancer cells.

A whey protein isolate–rhodamine B conjugate (WPI-RB) was synthesized to visualize changes in the location of a protein emulsifier in oil-in-water emulsions during digestion. An oil-soluble dye (Nile Red) was used to visualize changes in the lipid phase during digestion. Protein-labeled and lipid-labeled emulsions were passed through a simulated gastrointestinal tract consisting of mouth, stomach, and intestinal phases, and changes in protein and lipid location and morphology were monitored using confocal laser scanning microscopy. The proteins remained attached to the lipid droplet surfaces in the mouth and stomach, but formed large aggregates in the small intestine. The lipid droplets were highly flocculated in the mouth, highly coalesced in the stomach, and fully digested in the small intestine. Our results show that conjugation of fluorescence dyes to protein emulsifiers is useful for direct visualization of their location, as well as for understanding the behavior of food emulsions within the gastrointestinal tract.

Antibody-fluorophore conjugates have high potential for the specific fluorescence detection of target cancer cells in vitro and in vivo. However, the antibody-fluorophore conjugates described to date are inappropriate for real-time imaging of target cells because removal of unbound antibody is required to reduce background fluorescence before quantifiable analysis by microscopy. In addition, clinical applications of the conjugates have been limited by persistent background retention due to their long systemic circulation and nonspecific uptake. Here we report fast and real-time near-infrared fluorescence imaging of target cancer cells using an antigen-responsive molecular "on-off" sensor: the fluorescence of trastuzumab-ATTO680 conjugate is dark (i.e., turned off) in the extracellular region, while it becomes highly fluorescent (i.e., turned on) upon binding to the target antigen HER2 on cancer cell surface. This molecular switch enables fast and real-time imaging of target cancer cells in vitro and in vivo.

Unlike conventional

Nanomaterials have revolutionized cancer imaging, diagnosis, and treatment. Multifunctional nanoparticles in particular have been designed for targeted cancer therapy by modulating their physicochemical properties to be delivered to the target and activated by internal and/or external stimuli. This review will focus on the fundamental “chemical” design considerations of stimuli-responsive nanosystems to achieve favorable tumor targeting beyond biological barriers and, furthermore, enhance targeted cancer therapy. In addition, we will summarize innovative smart nanosystems responsive to external stimuli (e.g., light, magnetic field, ultrasound, and electric field) and internal stimuli in the tumor microenvironment (e.g., pH, enzyme, redox potential, and oxidative stress).

Here we report that new dual-targeted theranostic anti-cancer agents can be produced by simple conjugation of photosensitizers with tryptophan-containing peptide ligands via cyclic disulfide linkages. In the proof-of-concept study, photosensitizers conjugated with EGFR-targeting peptide GE11 (C-EGFR) were in close proximity with tryptophan residues in the conjugate, resulting in quenching of its fluorescence and singlet oxygen generation. C-EGFR specifically binds to target receptors on the cancer cell surface, after which it is internalized via receptor-mediated endocytosis. Intracellular cleavage of cyclic disulfide bonds allows separation of the photosensitizers from the tryptophan residue, after which they emit near-infrared (NIR) fluorescence and produce a phototoxic effect in the target cells. This strategy enabled us to accomplish simultaneous real-time NIR fluorescence imaging of EGFR-overexpressing cancer cells with high contrast and selective photodynamic therapy.

Objectives We produced hematoxylin and eosin (H&E) staining-like color images by using confocal laser scanning microscopy (CLSM), which can obtain the same or more information in comparison to conventional tissue staining. Methods We improved images by using several image converting techniques, including morphological methods, color space conversion methods, and segmentation methods. Results An image obtained after image processing showed coloring very similar to that in images produced by H&E staining, and it is advantageous to conduct analysis through fluorescent dye imaging and microscopy rather than analysis based on single microscopic imaging. Conclusions The colors used in CLSM are different from those seen in H&E staining, which is the method most widely used for pathologic diagnosis and is familiar to pathologists. Computer technology can facilitate the conversion of images by CLSM to be very similar to H&E staining images. We believe that the technique used in this study has great potential for application in clinical tissue analysis.

A redox-responsive specific theranostic agent was developed by the conjugation of photosensitizers with the tryptophan-containing GE11 peptide via a cleavable disulfide linker. It showed a potential utility for the target-cell-specific activatable fluorescence imaging and photodynamic therapy of triple-negative breast cancers.

Here, we propose the use of photosensitizer-complexed polypyrrole nanoparticles (PCe4@HANP) as activatable theranostics. The fluorescence emission and singlet oxygen generation of PCe4@HANP were mostly turned off in the extracellular region, but became highly fluorescent and phototoxic upon internalization into cancer cells, enabling real-time near-infrared fluorescence imaging and photodynamic therapy of cancer.

Radiotherapy (RT), along with surgery and chemotherapy, is a major modality of cancer therapy. Nevertheless, insufficient deposition of radiation energy in tumors and hypoxia-associated radioresistance remain the greatest challenges in RT. Here, we propose porous platinum nanoparticles as a new nanomedicine platform for solving these two problems at the same time using a single agent. Because of the combined advantages of a high-Z element and oxygen generation capability, porous platinum nanoparticles can significantly increase radiation-induced DNA damage, ROS stress, and cell cycle arrest by effectively depositing X-ray radiation energy within the cancer cells. Further, porous platinum nanoparticles increase tumor oxygenation by converting endogenic H2O2 to O2, thus greatly enhancing RT with no apparent in vivo toxicity to animals. This study presents a new nanomedicine strategy based on the use of porous high-Z metal nanoparticles with oxygen generation function for the synergistic enhancement of RT in cancer treatment.

Lymphadenectomy is a prerequisite for most malignancies to define the precise staging of cancer, as well as resect the possible metastases completely. While it improves prognosis, lymphadenectomy often causes postoperative edema or bleeding because of unclear surgical margins. In this study, we synthesized near-infrared (NIR) fluorescent nanoprobes with conjugating various mannose moieties on the surface to target macrophages in the lymph node. Armed with these NIR nanoprobes, we demonstrated the feasibility of intraoperative pan lymph nodes (PLN) mapping and real-time optical imaging under the NIR fluorescence imaging system. We found that even single mannose-conjugated ZW800-1 showed specific uptake in lymph nodes within 4 h, and multiple mannose-employed polyrotaxanes highlighted PLN efficiently with low background signals in major organs. This technology can help surgeons perform lymphadenectomy with ease and safety by identifying all regional lymph nodes proficiently after a single intravenous injection of NIR nanoprobes.

In this study, we synthesized manganese dioxide nanoparticles (MnO2 NPs) stabilized with biocompatible polymers (polyvinylpyrrolidone and polyacrylic acid) and analyzed their effect on non-small cell lung cancer (NSCLC) cells with or without gefitinib resistance in vitro. MnO2 NPs showed glutathione (GSH)-responsive dissolution and subsequent enhancement in magnetic resonance (MR) imaging. Of note, treatment with MnO2 NPs induced significant cytotoxic effects on NSCLC cells, and additional dose-dependent therapeutic effects were obtained upon X-ray irradiation. Normal cells treated with MnO2 NPs were viable at the tested concentrations. In addition, increased therapeutic efficacy could be achieved when the cells were treated with MnO2 NPs in hypoxic conditions. Therefore, we conclude that the use of MnO2 NPs in MR imaging and combination radiotherapy may be an efficient strategy for the imaging and therapy of NSCLC.

A new design for fluorescence probes of esterase activity that features a carboxylate-side pro-fluorophore is demonstrated with boron dipyrromethene (BODIPY)-based probes 1 a and 1 b. Because the design relies on the enzyme-catalyzed hydrolysis of an ester group that is not electronically activated, these probes exhibit a stability to background hydrolysis that is far superior to classical alcohol-side profluorophore-based probes, large signal-to-noise ratios, reduced sensitivity to pH variations, and high enzymatic reactivity. The utility of probe 1 a was established with a real-time fluorescence imaging experiment of endogenous esterase activity that does not require washing of the extracellular medium.

Hydrolysis of the oil phase in a water-in-oil-in-water (W/O/W) emulsion was studied using pancreatic lipase. The influence of the W/O volume fraction, lipase concentration, and concentration of emulsifiers used to prepare W/O/W emulsions on lipid digestion and release of encapsulated material were investigated. The extent of lipid digestion differed depending on the W/O volume and lipase concentration, and the amount of dye released was not dependent on the W/O content or lipase concentration. The concentration of emulsifiers did not affect the extent of digestion. The information obtained in this study will be useful for design of W/O/W emulsion formulations with controlled release profiles and lipid digestion.

Photodynamic therapy (PDT) is an established method for the treatment of cancer which utilizes light, a photosensitizer (PS), and oxygen. Unfavourable characteristics of most PSs, such as low solubility and tumour specificity have led many researchers to adopt nanoscale drug delivery platforms for use in PDT. Mesoporous silica nanoparticles (MSNs) form a significant part of that effort, due to their ease and controllability of synthesis, ease of loading, availability of diverse surface functionalization, and biocompatibility. Therefore, in this review, we discuss the properties of MSNs as they pertain to their use in PDT and review the latest advances in the field, comparing the different approaches currently being used.

Gastric cancer is the third most common cause of cancer mortality, and the survival rate of stage IV advanced gastric cancer (AGC) patients with distant metastasis is very low. Thus, the detection and eradication of disseminated cancer cells by targeting cell surface molecules in AGC would improve patient survival. The hyaluronic acid receptor, CD44, has various isoforms generated by alternative splicing, and some isoforms are known to be correlated to gastric cancer. In this study, to find out the most appropriate CD44v for targeting AGC, we analysed the expression differences of CD44 isoforms at the mRNA level in stomach cancer cell lines as well as in 74 patients with AGC by using exon-specific qRT-PCR. Among the CD44v isoforms, CD44v8-10 was determined as the most promising biomarker for the development of theranostic agents of gastric cancer. Next, we synthesised the conjugate of anti-CD44v9 antibody with near-infrared fluorophore or photosensitiser, and then demonstrated its feasibility for target cell-specific imaging and photoimmunotherapy in gastric cancer. As a result, these conjugates have clearly demarcated the surface of CD44v8-10 expressing cancer cells and showed efficient phototoxic effects. Therefore, this study revealed that CD44v8-10 is the efficient theranostic biomarker to target disseminated cancer cells in AGC.

Here we report indocyanine green (ICG)-loaded hollow mesoporous silica nanoparticles (ICG@HMSNP) as an activatable theranostic platform. Near-infrared fluorescence and singlet oxygen generation of ICG@HMSNP was effectively quenched (i.e. turned off) in its native state because of the fluorescence resonance energy transfer between ICG molecules. Therefore, ICG@HMSNP was nonfluorescent and nonphototoxic in the extracellular region. After the nanoparticles entered the cancer cells via endocytosis, they became highly fluorescent and phototoxic. In addition, intracellular uptake of ICG@HMSNP was 2.75 times higher than that of free ICG, resulting in an enhanced phototherapy of cancer.

Here we show that "off-on" type of photodynamic therapy agents could be developed using hollow mesoporous silica nanoparticles (HMSNPs), which can be used not only for enhancing delivery of photosensitizers to cancer cells but also for enabling switchable optical properties of the photosensitizers. Fluorescence and singlet oxygen generation of the photosensitizer-loaded HMSNP are turned off in its native state. In vitro cell studies showed that this HMSNP-based "off-on" agent may have potential utility in selective fluorescence detection and photodynamic therapy of cancers.

A gel-based encapsulation system was developed by incorporating W/O/W emulsions and 4-α-glucanotransferase (4αGTase) treated starch capable of thermoreversible gel formation, and its physical and release characteristics were investigated as functions of preparation conditions and temperature. Release properties of the W/O/W gels were affected by stability and encapsulation efficiency (EE) of W/O/W emulsions embedded within. Lower EE caused by longer sonication time increased fast release dye portion, which resulted in higher dye release rate, even though emulsion stability improved at longer sonication time. Lower dye release rate of W/O/W gels prepared with relatively higher W/O volume fractions slightly increased as temperature increased from room temperature to 90 °C. However, samples prepared with relatively lower W/O volume fractions showed higher dye release rate and a larger increase at 90 °C. The 4αGTase-treated starch gel improved W/O/W emulsion stability and thus retarded dye release even at 90 °C.

A boronate-based fluorescent probe 1 for the selective monitoring of intracellular peroxynitrite has been developed. The probe takes advantage of the fast reaction of an arylboronate group with peroxynitrite, yielding a corresponding phenol that undergoes spontaneous subsequent reactions to produce a strongly fluorescent product associated with a large turn-on signal.

A smart dual-targeted theranostic agent becomes highly fluorescent and phototoxic only when its linker is cleaved by tumor-associated lysosomal enzyme cathepsin B after internalization into folate receptor-positive cancer cells.

We have developed a folate receptor-specific activatable probe for in vivo near-infrared fluorescence imaging of ovarian cancer. This probe becomes highly fluorescent only when its linker is cleaved by a tumor-associated lysosomal enzyme cathepsin B after internalization into folate receptor-positive cancer cells.

We investigate a free-space propagation of a truncated terahertz beam created as a result of a partial reflection from a small-sized metallic reflector. By using terahertz time-domain spectroscopy, we obtain both magnitude and phase spectra of a clipped terahertz beam after its propagation by about 15 cm. Compared to a fully reflected terahertz beam, the partially reflected beam exhibits large variations in both magnitude and phase spectra in the entire spectral range investigated, i.e., from 0.2 to 1.3 terahertz. To model the free-space propagation of the truncated Gaussian beam, we decompose it using a super-Gaussian beam and several other Gaussian beams with phase factors separately assigned to each component. From this, we could successfully reproduce the experimental results, i.e., the modulations observed in both magnitude and phase spectra.

Objective— To investigate whether an intravenously injected cathepsin-B activatable theranostic agent (L-SR15) would be cleaved in and release a fluorescent agent (chlorin-e6) in mouse atheromata, allowing both the diagnostic visualization and therapeutic application of these fluorophores as photosensitizers during photodynamic therapy to attenuate plaque-destabilizing cathepsin-B activity by selectively eliminating macrophages. Approach and Results— Thirty-week-old apolipoprotein E knock-out mice (n=15) received intravenous injection of L-SR15 theranostic agent, control agent D-SR16, or saline 3× (D0, D7, D14). Twenty-four hours after each injection, the bilateral carotid arteries were exposed, and Cy5.5 near-infrared fluorescent imaging was performed. Fluorescent signal progressively accumulated in the atheromata of the L-SR15 group animals only, indicating that photosensitizers had been released from the theranostic agent and were accumulating in the plaque. After each imaging session, photodynamic therapy was applied with a continuous-wave diode-laser. Additional near-infrared fluorescent imaging at a longer wavelength (Cy7) with a cathepsin-B–sensing activatable molecular imaging agent showed attenuation of cathepsin-B–related signal in the L-SR15 group. Histological studies demonstrated that L-SR15–based photodynamic therapy decreased macrophage infiltration by inducing apoptosis without significantly affecting plaque size or smooth muscle cell numbers. Toxicity studies (n=24) showed that marked erythematous skin lesion was generated in C57/BL6 mice at 24 hours after intravenous injection of free chlorin-e6 and ultraviolet light irradiation; however, L-SR15 or saline did not cause cutaneous phototoxicity beyond that expected of ultraviolet irradiation alone, neither did we observe systemic toxicity or neurobehavioral changes. Conclusions— This is the first study showing that macrophage-secreted cathepsin-B activity in atheromata could be attenuated by photodynamic therapy using a protease-mediated theranostic agent.