Hybridization chain reaction-based nanoprobe for cancer cell recognition and amplified photodynamic therapy.

Precision diagnosis and effective treatment are the cores of early cancer therapy. Here, for the first time, we report a hybridization chain reaction-based nanoprobe for selective and sensitive cancer cell recognition and amplified photodynamic therapy.

In Situ Localization of Enzyme Activity in Live Cells by a Molecular Probe Releasing a Precipitating Fluorochrome.

Current enzyme-responsive, fluorogenic probes fail to provide in situ information because the released fluorophores tend to diffuse away from the reaction sites. The problem of diffusive signal dilution can be addressed by designing a probe that upon enzyme conversion releases a fluorophore that precipitates. An excited-state intramolecular proton transfer (ESIPT)-based solid-state fluorophore HTPQ was developed that is strictly insoluble in water and emits intense fluorescence in the solid state, with λex/em =410/550 nm, thus making it far better suited to use with a commercial confocal microscope. HTPQ was further utilized in the design of an enzyme-responsive, fluorogenic probe (HTPQA), targeting alkaline phosphatase (ALP) as a model enzyme. HTPQA makes possible diffusion-resistant in situ detection of endogenous ALP in live cells. It was also employed in the visualizing of different levels of ALP in osteosarcoma cells and tissue, thus demonstrating its interest for the diagnosis of this type of cancer.

Visualization of Endoplasmic Reticulum Aminopeptidase 1 under Different Redox Conditions with a Two-Photon Fluorescent Probe.

Endoplasmic reticulum aminopeptidase 1 (ERAP1), a metallopeptidase belonging to the M1 peptidase family, plays an important role in antigen processing in vivo. Additionally, many diseases are caused by ERAP1 perturbation. Thus, an efficient method for monitoring its content is extremely important for disease diagnosis and treatment. However, few fluorescent probes have been reported for efficiently monitoring ERAP1 in living cells and tissues. In this work, a two-photon fluorescent probe (SNCL) containing 1,8-naphthalimide (two-photon fluorophore), l-leucine (trigger moiety), and a methyl sulfonamide moiety (endoplasmic reticulum-targeting group) for imaging ERAP1 activity in living cells is reported for the first time. The optimized probe exhibited high sensitivity toward ERAP1, with about a 95-fold fluorescence enhancement at 550 nm. Herein, we monitored ERAP1 with SNCL by introducing interferon-γ to induce ERAP1 activity in living cells. The content of ERAP1 was dependent on the redox state of the endoplasmic reticulum, which was demonstrated by using SNCL to monitor the enzymatic activity of ERAP1 under different redox conditions. Excitingly, SNCL was also successfully applied for monitoring ERAP1 in tumor tissue with an imaging depth of 50-120 µm. In conclusion, SNCL not only can be used for the sensitive detection of endogenous ERAP1 in living cells and tumor tissues but also can serve as a potentially useful tool to reveal ERAP1-related diseases.

A mitochondrial-targeted prodrug for NIR imaging guided and synergetic NIR photodynamic-chemo cancer therapy.

Nontoxic prodrugs, especially activated by tumor microenvironment, are urgently required for reducing the side effects of cancer therapy. And combination of chemo-photodynamic therapy prodrugs show effectively synergetic therapeutic efficiency, however, this goal has not been achieved in a single molecule. In this work, we developed a mitochondrial-targeted prodrug PNPS for near infrared (NIR) fluorescence imaging guided and synergetic chemo-photodynamic precise cancer therapy for the first time. PNPS contains a NIR photosensitizer (NPS) and an anticancer drug 5'-deoxy-5-fluorouridine (5'-DFUR). These two parts are linked and caged through a bisboronate group, displaying no fluorescence and very low cytotoxicity. In the presence of H2O2, the bisboronate group is broken, resulting in activation of NPS for NIR photodynamic therapy and activation of 5'-DFUR for chemotherapy. The activated NPS can also provide a NIR fluorescence signal for monitoring the release of activated drug. Taking advantage of the high H2O2 concentration in cancer cells, PNPS exhibits higher cytotoxicity to cancer cells than normal cells, resulting in lower side effects. In addition, based on its mitochondrial-targeted ability, PNPS exhibits enhanced chemotherapy efficiency compare to free 5'-DFUR. It also demonstrated a remarkably improved and synergistic chemo-photodynamic therapeutic effect for cancer cells. Moreover, PNPS exhibits excellent tumor microenvironment-activated performance when intravenously injected into tumor-bearing nude mice, as demonstrated by in vivo fluorescence imaging. Thus, PNPS is a promising prodrug for cancer therapy based on its tumor microenvironment-activated drug release, synergistic therapeutic effect and "turn-on" NIR imaging guide.

Pyrophosphate-regulated Zn(2+)-dependent DNAzyme activity: an amplified fluorescence sensing strategy for alkaline phosphatase.

In this work, based on the fact that pyrophosphate (PPi) could regulate the activity of Zn(2+)-dependent DNAzyme, we for the first time report a fluorescence turn-on sensing system for alkaline phosphatase (ALP) with improved sensitivity via nonprotein-enzymatic signal amplification. A catalytic and molecular beacon (CAMB) design was employed to further improve its sensitivity. Taking advantage of the strong interactions between PPi and the Zn(2+), the cofactor Zn(2+) was caged, and the DNAzyme activity was effectively inhibited. The introduction of ALP, however, could catalyze the hydrolysis of PPi and release free Zn(2+), resulting in the activation of DNAzyme to catalyze the cleavage of the molecular beacon substrate with a remarkable increase of fluorescent signal. These optimized designs together allow a high sensitivity for ALP, with a detection limit of 20 pM observed, much lower than previously reported methods. It has also been used for detection of ALP in human serum with satisfactory results, demonstrating its potential applications in clinical diagnosis.

A nano-Ni based ultrasensitive nonenzymatic electrochemical sensor for glucose: enhancing sensitivity through a nanowire array strategy.

Highly ordered Ni nanowire arrays (NiNWAs) were synthesized for the first time using a template-directed electropolymerization strategy with a nanopore polycarbonate (PC) membrane template, and their morphological characterization were examined by scanning electron microscopy (SEM) and transmission electron microscope (TEM). A NiNWAs based electrode shows very high electrochemical activity for electrocatalytic oxidation of glucose in alkaline medium, which has been utilized as the basis of the fabrication of a nonenzymatic biosensor for electrochemical detection of glucose. The biosensor can be applied to the quantification of glucose with a linear range covering from 5.0x10(-7) to 7.0x10(-3) M, a high sensitivity of 1043 microA mM(-1) cm(-2), and a low detection limit of 1x10(-7) M. The experiment results also showed that the sensor exhibits good reproducibility and long-term stability, as well as high selectivity with no interference from other oxidable species.

In situ chemical reductive growth of platinum nanoparticles on glass slide for the mass fabrication of biosensors.

Platinum nanoparticles (PtNPs) attached to glass slide surface was successfully prepared by using a simple in situ chemical reduction method. In this method, a approximately 10nm gold layer was first sputtered uniformly onto the glass slide surface, PtNPs could be grown directly on the gold layer by immersing the glass slide into the grown solution containing H(2)PtCl(4) and ascorbic acid. The gold layer sputtered uniformly serves as "seed" for the following growth of PtNPs and high dense of PtNP modified film can be prepared. Control experiment without the gold layer found no obvious formation of PtNPs indicating the importance of the "seed". The electrocatalytic effect of the PtNP film was investigated with the detection of hydrogen peroxide and for the fabrication of biosensors. Glucose oxidase was selected and directly electrodeposited onto the PtNPs modified surface. The resulting biosensor has a fast response time (<10s) with wide linear range (5x10(-6) to 2x10(-2)). The fabrication method is simple, convenient and can be used for the mass fabrication of biosensors. The present preparation method of PtNPs modified film could be used for the preparation of other metal nanoparticle and find electrochemical applications as well as for optical uses.