Self-Assembly-Based Nanoprobes for the Simultaneous Detection and Downregulation of HSP90α mRNA to Enhance Photothermal Therapy.

Although photothermal therapy (PTT) has been widely applied for tumor treatment, tumor cells thermotolerance still limits PTT efficiency. Since the overexpressed HSP90α in tumor cells further enhances thermotolerance and protects them from PTT damage, a new nanoprobe that can specifically detect and downregulate HSP90α mRNA was developed to enhance the PTT effect. Based on the HSP90α mRNA sequence, the nanoprobe Au-DNA1/DNA2 can specifically bind to HSP90α mRNA for recovering its fluorescence and further inhibit the synthesis of HSP90α to reduce tumor heat tolerance. Moreover, another nanoprobe, Au-DNA3, can self-assemble with the Au-DNA1 nanoprobe after the detection to form Au aggregations to enhance PTT afterward for better efficiency. Simultaneously, such a design improves tissue penetration and tumor retention, thereby reducing the damage to the surrounding normal tissues. Both in vitro and in vivo experiments showed that the nanoprobes have excellent tumor diagnosis and cancer treatment capabilities, which is of great significance for clinical translational applications.

Gold Nanoparticles Functionalized with Au-Se-Bonded Peptides Used as Gatekeepers for the Off-Target Release of Resveratrol in the Treatment of Triple-Negative Breast Cancer.

Resveratrol has been garnering considerable attention as a promising chemopreventive and chemotherapeutic drug against metastatic tumors such as triple-negative breast cancer (TNBC). However, the potential in vivo application of resveratrol has been highly limited due to its poor solubility, rapid conjugation, low bioavailability, and bioactivity. In this study, a silica mesoporous nanoparticle (MSN)-based drug delivery system (DDS), named Au-Se@MSN, is developed to deliver the loaded resveratrol, endowing it with properties of targeted delivery, excellent bioavailability, and antioxidation of resveratrol. In Au-Se@MSN(RES), gold nanoparticles functionalized with selenol-modified uPA-specific peptides act as gatekeepers to avoid the interference of glutathione in the bloodstream and realize negligible premature release of resveratrol during delivery. Au-Se@MSN(RES) shows prolonged resveratrol release at the tumor site and endows resveratrol with a remarkable in vitro therapeutic effect. The pharmacological dose of resveratrol treatment on MDA-MB-231 cells was found to result in the generation of a high level of NAD(P)H other than H2O2, indicating reductive stress instead of oxidative stress involved in the resveratrol therapeutic process. In vivo experiments showed that Au-Se@MSN greatly improves the chemotherapeutic effect of resveratrol on mice bearing TNBC tumors, and damage to normal tissues and cells is negligible. Overall, Au-Se@MSN is a potential tool for further studies on the anticancer mechanism and clinical applications of resveratrol.

Au-Se bonded nanoprobe for prostate specific antigen detection in serum.

The detection of prostate specific antigen (PSA) in serum can realize early diagnosis of prostate cancer and prevent the occurrence of prostate tumors, as well as offering guidance during the therapy. Herein, a Au-Se bonded nanoprobes that can specifically detect PSA was designed and constructed. The peptide chains that can be specifically cleaved by PSA were firstly functionalized with fluorescent dye and selenol, and then bind to the Au nanoparticles to produce the probe. The dye's fluorescence was quenched due to the FRET effect, but recovered by PSA's cutting. The nanoprobe can detect PSA in serum with extraordinary anti-interference ability against other proteins (detection range 1-40 ng/mL). This work provides a new method for the detection of PSA in serum, and has potential guiding significance for clinical PSA detection.

Se-modified gold nanorods for enhancing the efficiency of photothermal therapy: avoiding the off-target problem induced by biothiols.

Tumor-targeting gold nanorods (AuNRs) assembled through Au-S bonds have been widely used for photothermal therapy (PTT) via intravenous injection. However, with extended in vivo circulation times, biothiols can replace some S-modified targeting ligands on the surface of the AuNRs, which lowers their targeting efficacy towards cancer cells, resulting in a non-ideal PTT effect. To address this problem, herein, we utilized Se-modified AuNRs to establish a dual functional nanoprobe (Casp-RGD-Se-AuNRs) for improving the therapeutic effect and real-time monitoring of Caspase-9 levels to indicate the degree of cell apoptosis. The experiments demonstrated that the Casp-RGD-Se-AuNRs are better at avoiding interference from biothiols than the S-modified nanoprobe (Casp-RGD-S-AuNRs) for extended blood-circulation times after intravenous injection, significantly improving the PTT efficacy via more effectively targeting cancer cells. Simultaneously, the change of Caspase-9 levels visually shows the degree of apoptosis. Moreover, an in vivo study showed that, compared with the S-modified nanoprobe, the Se-modified nanoprobe exhibits a higher delivery efficiency to the tumor region after intravenous injection (accumulation in the tumor increased by 87%) and a better anticancer efficacy under NIR light irradiation (the tumor inhibition rate increased 6-fold). This work provides a valuable strategy to overcome the off-target problem, and new ideas for avoiding interference by biomolecules during blood circulation.

Reconstruction of nano-flares based on Au-Se bonds for high-fidelity detection of RNA in living cells.

We have, for the first time, developed a Au-Se-DNA nanoprobe by upgrading the conventional Au-S bonds of nano-flares to more stable Au-Se bonds for high-fidelity imaging of target RNAs in living cells. The design concept is potentially introduced into various Au-DNA nanosensors that offer wide application prospects in research and clinical practice.

Homotypic cell membrane-cloaked biomimetic nanocarrier for the accurate photothermal-chemotherapy treatment of recurrent hepatocellular carcinoma.

BACKGROUND: Tumor recurrence in patients after surgery severely reduces the survival rate of surgical patients. Targeting and killing recurrent tumor cells and tissues is extremely important for the cancer treatment. RESULTS: Herein, we designed a nano-biomimetic photothermal-controlled drug-loading platform HepM-TSL with good targeting ability and immunocompatibility for the treatment of recurrent hepatocellular carcinoma. HepM-TSL can accurately target the recurrent tumor area with the aid of the cloaked homotypic cell membrane and release the chemotherapy drugs in a controlled manner. In vivo results have confirmed that HepM-TSL loaded with drugs and photosensitizer achieves the synergistic treatment of recurrent hepatocellular carcinoma with good therapeutic effect and slight side effects. CONCLUSION: Accordingly, HepM-TSL provides a sound photothermal-chemotherapy synergistic strategy for the treatment of other recurrent cancers besides of recurrent hepatocellular carcinoma.

An Au-Se nanoprobe for the evaluation of the invasive potential of breast cancer cells via imaging the sequential activation of uPA and MMP-2.

Urokinase-type plasminogen activator (uPA) has been shown to activate matrix metalloproteinase-2 (MMP-2) that leads to the migration and invasion of breast cancer cells. Overexpressed uPA and MMP-2 are regarded as signs of malignant tumors in clinical practice. Therefore, real-time monitoring of the sequential activation of these two signal molecules may have important implications for the evaluation of the invasive potential and tumor progression of breast cancer. However, due to the complicated intracellular environment, visualizing the dynamic changes of protein expression levels in living cells with a noninvasive method is still a great challenge. Here, a novel gold-selenium (Au-Se) fluorescent nanoprobe with excellent selectivity and strong anti-interference capability was designed for the simultaneous in situ imaging of uPA and MMP-2 and real-time monitoring of their changes in living cells. The imaging results demonstrated that the nanoprobe achieved a better prevention of glutathione interference compared to the conventional Au-S nanoprobe, thus it could be applied to actually reflect the expression level of uPA and MMP-2 in different breast cancer cells. Furthermore, the Au-Se nanoprobe could visually present the activation process of the two signal molecules, which play a dual role of insuring the invasiveness evaluation of breast cancer cells. Overall, our work offers a visual biomarker detection method for the judgment of the degree of breast cancer malignancy, and also provides an effective strategy to investigate the relationships among signal molecules of other signaling pathways in the future.

Real-Time in Situ Visualizing of the Sequential Activation of Caspase Cascade Using a Multicolor Gold-Selenium Bonding Fluorescent Nanoprobe.

The caspase cascade is an ensemble of very important signaling molecules that plays a critical role in cell apoptosis. Real-time monitoring of the upstream and downstream activation relationships of the caspases in the signal pathway is of great significance for understanding the regulatory mechanisms of these signaling molecules in the development of various diseases. Herein, a multicolor fluorescent nanoprobe, GNP-Se-Casp, has been developed based on Au-Se bonding for real-time in situ monitoring caspase- (casp-) 3, 8, and 9 during cell apoptosis. In the real-time fluorescence imaging of apoptotic HeLa cells induced by staurosporine using GNP-Se-Casp, the fluorescence signals corresponding to casp-8 and casp-9 sequentially turn on, followed by the appearance of the fluorescence of casp-3, which visualizes the upstream and downstream relationships of casp-3, -8, and -9. Thus, GNP-Se-Casp is an effective tool for real-time in situ monitoring of caspase cascade activation in the apoptosis process of tumor cells. This design strategy is easily adaptable to in situ detection of other signal molecules, especially those with upstream and downstream activation relationships.

Au-Se-Bond-Based Nanoprobe for Imaging MMP-2 in Tumor Cells under a High-Thiol Environment.

The gold nanosensors based on the Au-S bond have been widely applied to biochemical detections. However, signal distortion caused by biothiols has been seldom mentioned and urgently needs to be solved. Herein, we designed a novel but easily assembled gold nanoprobe by coupling a selenol-modified peptide with FITC onto the gold nanoparticle's surface via an Au-Se bond for fluorescence imaging of a tumor marker matrix, metalloproteinases 2 (MMP-2). Compared to the Au-S probes, the Au-Se probes display high thermal stability and a very good anti-interference ability toward glutathione under simulated physiological conditions. More importantly, the Au-Se nanoprobe exhibits a high-fidelity fluorescent signal toward MMP-2, effectively avoiding interference caused by high levels of thiol compounds in vivo. In addition, in vivo experiments further proved that no significant signal intensity change for the tumor cells treated by the Au-Se probes was observed before and after eliminating glutathione. Hence, we believe such Au-Se probes with in vivo glutathione interfering resistance offer new routes and perspectives in biology and medicine in the future.

A nanosensor for in vivo selenol imaging based on the formation of Au-Se bonds.

Selenol is a key metabolite of Na2SeO3 and plays an important role in many physiological and pathological processes. The real-time monitoring of selenol is of scientific interest for understanding the anti-cancer mechanism of Na2SeO3. Based on selenol's ability to specifically break AuS bonds and form more stable AuSe bonds on the surfaces of gold nanoparticles (AuNPs), we developed a novel near-infrared fluorescent nanosensor (Cy5.5-peptide-AuNPs) for detecting selenol. The nanosensor exhibited rapid response to selenol with high selectivity and sensitivity, and it was successfully used to image changes in the selenol level in HepG2 cells during Na2SeO3-induced apoptosis. Moreover, in vivo fluorescence imaging of selenol was obtained from H22 tumor-bearing mice injected with both the nanosensor and sodium selenite. The results showed that the tumor cell apoptosis induced by Na2SeO3 is correlated with high-level of selenol under hypoxic conditions. We believe that this nanosensor could serve as a powerful tool for monitoring selenol and exploring the physiological function of selenol in a variety of physiological and pathological contexts and that the probe-designed strategy will provide a new platform for research on relevant selenium chemistry.

Study of highly selective and efficient thiol derivatization using selenium reagents by mass spectrometry.

This paper reports a systemic mass spectrometry (MS) investigation of a novel strategy for labeling biological thiols, involving the cleavage of the Se-N bond by thiol to form a new Se-S bond. Our data show that the reaction is highly selective, rapid, reversible, and efficient. Among 20 amino acids, only cysteine is reactive toward Se-N containing reagents and the reaction occurs in seconds. With the addition of dithiothreitol, peptides derivatized by selenium reagents can be recovered. The high reaction selectivity and reversibility provide potential in both selective identification and isolation of thiols from mixtures. Also, with dependence on the selenium reagent used, derivatized peptide ions exhibit tunable dissociation behaviors (either facile cleavage or preservation of the formed Se-S bond upon collision-induced dissociation), a feature that is useful in proteomics studies. Equally importantly, the thiol derivatization yield is striking, as reflected by 100% conversion of protein beta-lactoglobulin A using ebselen within 30 s. In addition, preliminary applications such as rapid screening of thiol peptides from mixtures and identification of the number of protein free and bound thiols have been demonstrated. The unique selenium chemistry uncovered in this study would be valuable in the MS analysis of thiols and disulfide bonds of proteins/peptides.

Use of selenium to detect mercury in water and cells: an enhancement of the sensitivity and specificity of a seleno fluorescent probe.

Seleno fluorescent probe: An organoselenium fluorescent probe (FSe-1) for mercury was designed based on the irreversible deselenation mechanism. FSe-1 exhibits an ultrahigh selectivity and sensitivity for Hg(2+) detection only for reactive selenium atom sites, due the strong affinity between Se and Hg. Furthermore, the new probe has been successfully used for imaging mercury ions in RAW 264.7 cells (a mouse macrophage cell line; see figure).Inspired by the antitoxic function of selenium towards heavy-metal ions, we designed an organoselenium fluorescent probe (FSe-1) for mercury. The reaction of FSe-1 and Hg(2+) is an irreversible deselenation mechanism based on the selenophilic character of mercury. FSe-1 exhibits an ultrahigh selectivity and sensitivity for Hg(2+) detection only for reactive selenium atom sites due to the strong affinity between Se and Hg. The experimental results proved that FSe-1 was selective for Hg(2+) ions over other relevant metal ions and bioanalytes, and also showed an enhancement in sensitivity of up to 1.0 nM, which is lower than the current Environmental Protection Agency standard for drinking water. Furthermore, the new probe has been successfully applied to the imaging of mercury ions in RAW 264.7 cells (a mouse macrophage cell line) with high sensitivity and selectivity.