Search

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. [ABSTRACT FROM AUTHOR]

Unique physicochemical characteristics of graphitic carbon nitride (g-CN) nanosheets suit them to be a useful tool for two-photon fluorescence bioimaging. Current g-CN nanosheets based imaging probes typically use the "always-on" design strategies, which may suffer from increased fluorescence background and limited contrast. To advance corresponding applications, g-CN nanosheets based activatable two-photon fluorescence probes remain to be explored. For the first time, we developed an activatable two-photon fluorescence probe, constructed from a nanoassembly of g-CN nanosheets and hyaluronic acid (HA)-gold nanoparticles (HA-AuNPs), for detection and imaging of hyaluronidase (HAase) in cancer cells. The deliberately introduced HA in our design not only functions as the buffering layer for stabilizing AuNPs and inducing corresponding self-assembly on g-CN nanosheets but also as a pilot for targeting HA receptors overexpressed on cancer cell surfaces. Our results show that the developed nanoassembly enables specific detection and activatable imaging of HAase in cancer cells and deep tissues, with superb signal-to-background ratio and high sensitivity. This nanoassembly can afford a promising platform for highly specific and sensitive imaging of HAase and for related cancer diagnosis. [ABSTRACT FROM AUTHOR]

Here, we propose a strategy for unique nuclear-shell biopolymers initiated by telomere elongation for telomerase activity detection and precise drug delivery to individual cancer cells. Telomerase-triggered DNA rolling-circle amplification (RCA) is used to assemble nuclear-shell biopolymers with signal molecules for selective cancer cell recognition and efficient drug delivery to targeted individual cells. This strategy not only should allow the creation of clustered 5-carboxyfluorescein (FAM)-fluorescence spots in response to human-telomerase activity in individual cancer cells but also could efficiently deliver drugs to reduce the undesired death of healthy cells. These findings offer new opportunities to improve the efficacy of cancer cell imaging and therapy. [ABSTRACT FROM AUTHOR]

We report a surprising discovery that Prussian blue (PB) can be employed as a highly sensitive and background-free resonant Raman reporter. Conventional Raman reporters show multiple spectral bands in the fingerprint region, which are generally overlapped with those from dominant endogenous biomolecules, and are thus difficult to be separated. Herein, we found that PB only possesses a strong and sharp single-band in the cellular Raman-silent region, where no Raman signals from biological species were observed. Therefore, the Raman spectra from PB and endogenous biomolecules are completely resolved without resorting to complicated spectral unmixing. Moreover, PB holds a strong UV-vis absorption band between 500 and 900 nm, which is resonant with the incident detection lasers, providing extremely high sensitivity. Through assembly of PB onto plasmonic cores, a new surface-enhanced resonance Raman scattering (SERRS) probe was achieved with a high signal-to-background ratio (SBR). We demonstrated the performance of the PB-based SERRS tags for high-sensitivity immunoassay and cancer cell imaging. [ABSTRACT FROM AUTHOR]

Due to its large enhancement effect, nanostructure-based surface-enhanced Raman scattering (SERS) technology had been widely applied for bioanalysis and cell imaging. However, most SERS nanostructures suffer from poor signal reproducibility, which hinders the application of SERS nanostructures in quantitative detection. We report an etching-assisted approach to synthesize SERS-active plasmonic nanoparticles with 1 nm interior nanogap for multiplex quantitative detection and cancer cell imaging. Raman dyes and methoxy poly(ethylene glycol) thiol (mPEG-SH) were attached to gold nanoparticles (AuNPs) to prepare gold cores. Next, Ag atoms were deposited on gold cores in the presence of Pluronic F127 to form a Ag shell. HAuCl4 was used to etch the Ag shell and form an interior nanogap in Au@AgAuNPs, leading to increased Raman intensity of dyes. SERS intensity distribution of Au@AgAuNPs was found to be more uniform than that of aggregated AuNPs. Finally, Au@AgAuNPs were used for multiplex quantitative detection and cancer cell imaging. With the advantages of simple and rapid preparation of Au@AgAuNPs with highly uniform, stable, and reproducible Raman intensity, the method reported here will widen the applications of SERS-active nanoparticles in diagnostics and imaging. [ABSTRACT FROM AUTHOR]

Multipurpose polymer nanoscaffolds for cellular imaging and delivery of anticancer drug are urgently required for the cancer therapy. The present investigation reports a new polymer drug delivery concept based on biodegradable polycaprolactone (PCL) and highly luminescent π-conjugated fluorophore as dual functional nanocarrier for cellular imaging and delivery vehicles for anticancer drug to cancer cells. To accomplish this goal, a new substituted caprolactone monomer was designed, and it was subjected to ring opening polymerization using a blue luminescent bishydroxyloligo-phenylenevinylene (OPV) fluorophore as an initiator. A series of A-B-A triblock copolymer building blocks with a fixed OPV π-core and variable chain biodegradable PCL arm length were tailor-made. These triblocks self-assembled in organic solvents to produce well-defined helical nanofibers, whereas in water they produced spherical nanoparticles (size ~150 nm) with blue luminescence. The hydrophobic pocket of the polymer nanoparticle was found to be an efficient host for loading water insoluble anticancer drug such as doxorubicin (DOX). The photophysical studies revealed that there was no cross-talking between the OPV and DOX chromophores, and their optical purity was retained in the nanoparticle assembly for cellular imaging. In vitro studies revealed that the biodegradable PCL arm was susceptible to enzymatic cleavage at the intracellular lysosomal esterase under physiological conditions to release the loaded drugs. The nascent nanoparticles were found to be nontoxic to cancer cells, whereas the DOX-loaded nanoparticles accomplished more than 80% killing in HeLa cells. Confocal microscopic analysis confirmed the cell penetrating ability of the blue luminescent polymer nanoparticles and their accumulation preferably in the cytoplasm. The DOX loaded red luminescent polymer nanoparticles were also taken up by the cells, and the drug was found to be accumulated at the perinuclear environment. The new nanocarrier approach reported in the present manuscript accomplishes both cellular imaging and delivering drugs to intracellular compartments in a single polymer system. The present investigation is one of the first examples to demonstrate the dual functional biodegradable luminescence nanocarrier concept in the literature, and the studies established this proof-of-concept in cellular imaging and drug delivery in cancer cells. [ABSTRACT FROM AUTHOR]

Achieving highly selective and sensitive detection/visualization of intracellular biological events through the use of cell-penetrable, bioanalyte-activatable, tum-on probes is dependent on the presence of specific event-linked cellular biomarkers, if and only if there exist activatable probes that appropriately respond to the biomarker analyte. Here is described the evaluation of, and use in cellular imaging studies, a previously undisclosed naphthalimide probe QMeNN, whose fluorescence is deactivated by photoinduced electron transfer (PeT) quenching that results from the presence of a covalently linked biomarkerspecific quinone trigger group. Highly selective and rapid activation of the quinone group by the human cancer tumor-linked NAD(P)H:quinone oxido-reductase isozyme 1 (hNQO1) results in fast trigger group removal to yield a highly fluorescent green-energy-range reporter that possesses a high molar absorptivity; there is a 136-fold increase in brightness for the enzymatically produced reporter versus probe precursor, a value 4 times greater than previously reported for the hNQO1 analyte. The novel probe is taken up and activated rapidly within only hNQO1 -positive human cancer cells; addition of an hNQO1 inhibitor prevents the selective activation of the probe. Comparison of cytosolic fluorescence intensity in positive cells versus background in negative cells yields a quantitative metric (positive-to-negative ratio, PNR) for judging hNQO1 activity. We show it is possible to determine hNQOl presence in previously studied colorectal cancer cells and the unexplored ovarian cancer cell line NIH:OVCAR-3, with respective PNR values of 926 and 34 being obtained. Even with 10 min probe incubation, ready discrimination of positive cells from negative cells is achieved. Cell viability is unaffected by probe presence, thereby highlighting the practicality of probe use in live-cell imaging applications. [ABSTRACT FROM AUTHOR]

The lysosome-targetable OFF-ON type pH sensor that does not emit at pH = 4.0 is adopted for the selective detection of cancer cells, and the acidity difference of lysosomes in cancer and normal cells is verified. Three pH probes based on Darrow Red derivatives were designed and prepared that were demonstrated to be lysosome-specific biomarkers with inducible emission at 580-850 nm by the comparable in cellular imaging assays using HeLa, KB, and V79 cells. Of these, a pyridineium-2-yl Darrow Red analogue with a pKa of 2.4 was found to be a lysosome tracker for cancer cells, it is a unique pH sensor for the optical identification and distinction of cancer cells from normal cells and has potential application as a fluorescent biomaker of cancer cells in in vitro assays. [ABSTRACT FROM AUTHOR]

Two-photonfluorescence microscopy is a widely used noninvasivebioimaging technique because of unique advantages such as a largepenetration depth and 3D mapping capability. Ideal two-photon fluorophoresrequire large two-photon absorption cross sections and red emissionwith high quantum yields. Here we report red-emitting-dye-doped conjugatedpolymer nanoparticles that display high two-photon excitation brightness.In these nanoparticles, conjugated polymer (PFV) was chosen as a two-photonlight-harvesting material, and red-emitting dyes (MgPc and Nile red)were chosen as the energy acceptors and red-emitting materials. Two-photonexcitation fluorescence of MgPc and Nile red was enhanced by up to∼53 and ∼240 times, respectively. We have successfullydemonstrated the application of these conjugated polymer-based nanoparticlesin two-photon excitation cancer cell imaging with an excellent contrastratio. This concept could become a general approach to the preparationof two-photon excitation red-emitting materials for deep-tissue live-cellimaging with high contrast. [ABSTRACT FROM AUTHOR]

In this study, we describe a solutionprocedure for the preparationand surface modification of photostable colloidal silicon quantumdots (SiQDs) for imaging of cancer cells. Photoluminescent SiQDs weresynthesized by reduction of halogenated silane precursors using amicroemulsion process. It was shown that 1,8-nonadiyne molecules couldbe grafted onto the surface of hydrogen-terminated SiQDs via ultraviolet(UV)-promoted hydrosilylation, demonstrated by Fourier transform infraredspectroscopy (FTIR) measurements. In addition, various azide moleculeswere coupled onto nonadiyne-functionalized particles, rendering particlesdispersible in selected polar and nonpolar solvents. The photoluminescenceof functionalized SiQDs was stable against photobleaching and didnot vary appreciably within biologically applicable pH and temperatureranges. To demonstrate compatibility with biological systems, water-solubleSiQDs were used for fluorescent imaging of HeLa cells. In addition,the SiQDs were shown to be non-cytotoxic at concentrations up to 240μg/mL. The results presented herein provide good evidence forthe versatility of functionalized SiQDs for fluorescent bioimagingapplication. [ABSTRACT FROM AUTHOR]

Scanning electrochemical microscopy (SECM) is increasingly applied to study and image live cells. Quantitative analyses of biological systems, however, still remain challenging. In the presented study, single human adenocarcinoma cervical cancer cells are electrochemically investigated by means of SECM. The target cell's electrochemical response is observed over time under the influence of green tea catechins (GTC), which are suggested to offer chemopreventive and therapeutic effects on cancer. The electrochemical response of living target cells is measured experimentally and quantified in an apparent heterogeneous rate constant by using a numerical model, based on forced convection during high speed SECM imaging. The beneficial effect of GTC on cancer cells could be confirmed by SECM, and the presented study shows an alternative approach toward unraveling the mechanisms involved during inhibition of carcinogenesis. [ABSTRACT FROM AUTHOR]