Bioimaging Of Cancer Cells Research Articles

Targeted Bioimaging of Cancer Cells Using Free Folic Acid-Sensitive Molybdenum Disulfide Quantum Dots through Fluorescence "Turn-Off".

In the present study, a proficient way for targeted bioimaging of folate receptor (FR)-positive cancer cells using free folic acid (FA)- and MoS2 QD-based nanoprobes is discussed along with its advantages over the preparation of orthodox direct FA-nanoprobe bioconjugates for the imaging. The water-soluble MoS2 QDs of size 4-5 nm with cysteine functionalization are synthesized by a simplistic bottom-up hydrothermal method. The as-prepared MoS2 QDs exhibit the blue emission with the highest emission intensity at 444 nm upon excitation of 370 nm. The MoS2 QDs are too sensitive toward FA to produce an effective and stable nanofiber structure through supramolecular interaction, which demonstrates ∼97% quenching of fluorescence. Moreover, the high selectivity and sensitivity of MoS2 QDs toward FA make the MoS2 QD-based nanoprobe an appropriate candidate for FA-targeted "turn-off" imaging probes for in vivo study of FA-pretreated FR-overexpressed cancer cells. It is obvious from the confocal microscopy images that the FA-pretreated B16F10 cancer cells show higher population of dimmed fluorescence compared to untreated cancer cells and HEK-293 normal cells. The flow cytometry study quantitatively reveals the significant difference of the geometric mean of fluorescence between FA-pretreated and untreated B16F10 cancer cells. Hence, these MoS2 QD-based nanoprobes can be applied as potential nanoprobes for the prediagnosis of cancer through targeted bioimaging.

Biocompatible exosomes nanodrug cargo for cancer cell bioimaging and drug delivery

Therapy against cancer remains a daunting issue for human health, despite remarkable innovations in many areas of pathology. In situ biosynthesized nanoclusters bestow a novel remedy for carcinogenic cell imaging. Exosomes have received special attention as an efficient tool for the diagnosis of various diseases, including cancers. All types of cells (healthy or diseased) generate exosomes, making them significantly unique for relevant disease diagnosis and treatment. In this contribution, we exploit the possibility of utilizing the exosomes to facilitate chemotherapeutics, viz. the combination of doxorubicin (Dox) and biosynthesized silver nanoclusters in cancer cells. Our study showed a new facile way for bioimaging of cancer cells using biosynthesized silver-DNA nanoclusters, and thus further targeting cancer cells using the relevant cancer exosomes as drug delivery cargo. After isolating exosomes from neoplastic cells, i.e. HeLa, loaded with the drug, and treating other neoplastic cells with cargo-loaded isolated exosomes, we found that cargo-loaded isolated exosomes can readily enter into the targeted cancer cells and efficiently kill these neoplastic cells. This raises the possibility of acting as a novel facile modality for target cancer theranostics with high efficiency and biocompability.

Functionalized Fluorescent Silica Nanoparticles for Bioimaging of Cancer Cells.

Functionalized fluorescent silica nanoparticles were designed and synthesized to selectively target cancer cells for bioimaging analysis. The synthesis method and characterization of functionalized fluorescent silica nanoparticles (50–60 nm), as well as internalization and subcellular localization in HeLa cells is reported here. The dye, rhodamine 101 (R101) was physically embedded during the sol–gel synthesis. The dye loading was optimized by varying the synthesis conditions (temperature and dye concentration added to the gel) and by the use of different organotriethoxysilanes as a second silica precursor. Additionally, R101, was also covalently bound to the functionalized external surface of the silica nanoparticles. The quantum yields of the dye-doped silica nanoparticles range from 0.25 to 0.50 and demonstrated an enhanced brightness of 230–260 fold respect to the free dye in solution. The shell of the nanoparticles was further decorated with PEG of 2000 Da and folic acid (FA) to ensure good stability in water and to enhance selectivity to cancer cells, respectively. In vitro assays with HeLa cells showed that fluorescent nanoparticles were internalized by cells accumulating exclusively into lysosomes. Quantitative analysis showed a significantly higher accumulation of FA functionalized fluorescent silica nanoparticles compared to nanoparticles without FA, proving that the former may represent good candidates for targeting cancer cells.

Synthesis of CuInS2 and CuInS2@ZnX (X = S, Se) nanoparticles for bioimaging of cancer cells using electrochemically generated S2- and Se2-

An electrochemical approach has been used for the aqueous synthesis of low-toxicity and eco-friendly copper indium sulfide (CuInS2) nanocrystals, and related core@shell systems (CuInS2@ZnX, where X = S2- and Se2-). The chalcogenide precursors (S2-, Se2-) were generated in electrochemical cavity cell, using a constant current electrolysis (i = 30 mA and Q = 11.5C), in the presence of metallic precursors (In3+, Cu+, Zn2+), room temperature and argon atmosphere. Firstly, In2S3 seeds were obtained in the intermediate compartment of the cell and converted to CuInS2 by thermoactivated diffusion (colloidal solution under reflux) of Cu+ ions into the In2S3 lattice. Cu+/In3+ ratios = 0.25 and 0.125 were tested for the production of CuInS2 stabilized by l-glutathione (GSH), and characterized by UV–vis and emission spectroscopy, XRD, HRTEM and zeta potential. CuInS2@ZnX nanoparticles were prepared by using the same electrochemical system, paired electrolysis and Zn sacrificial anode. Nanocrystals prepared under Cu+/In3+ = 0.125 reached 3.1% (CuInS2), 4.6% (CuInS2@ZnSe), and 9.6% (CuInS2@ZnS) quantum yields. The CuInS2@ZnX systems presented high cell viability (85%–94%) and internalization in cytosol region of HeLa cells, showing high potential for biological labeling.

Ecofriendly Multiphase Aqueous Colloidal Based on Carboxymethylcellulose Nanoconjugates with Luminescence Properties for Potential Bioimaging Cancer Cells

Quantum dots (QD) or semiconductor nanoparticles are within the most researched nanomaterials currently. Their attractive optical, electronic and chemical properties can be adjusted by varying composition, size, and synthesis parameters. This tunability pushes these nanocrystals into different types of applications such as biomedical and environmental ones. One of the concerns about their use regards the inherent toxicity related to the most efficient emission QD based on heavy metals. In this context, we report the synthesis of eco-friendly Ag-In-S (AIS) and Zn-Ag-In-S (ZAIS) QD conjugated with a biodegradable polymer, carboxymethylcellulose (CMC). Colloidal AIS were synthesized using an eco-friendly aqueous route at room temperature. Co-precipitation process was controlled via CMC with two degrees of substitution (DS) and under different pH conditions. In order to improve the as-prepared AIS’ optical properties, ZnS was deposited over the nanocrystals with further annealing process, creating a core/shell alloyed nanostructure. The obtained QD were extensively characterized considering their optical, physicochemical and morphological features. Results demonstrated the presence of fairly monodispersed photoluminescent nanoparticles with average size of 3.0 nm for AIS QD and 4.3 nm for ZAIS QD. Moreover, modifying the synthesis parameters, it was possible to tune and improve the emission of the fluorescent nanoparticles (λem = 500 to 900 nm). Diffraction patterns suggested the formation of solid solutions of AIS and its correspondent binary compounds. Furthermore, cellular uptake assays demonstrated a more rapid internalization of fluorescent AIS and ZAIS nanoconjugates by cancer cells when compared to normal cells. These luminescent materials showed the potential of use in a wide range of applications, such as bioimaging of cancer cells.

Selective bioimaging of cancer cells and detection of HSA with indomethacin-based fluorescent probes.

Two fluorescent probes were designed by connecting indomethacin to coumarin through different linkers. The introduction of indomethacin quenched the fluorescence of coumarin-based probes with apparent red-shifts in the absorption and emission maxima, probably due to the photoinduced electron transfer (PET) from the indomethacin to the fluorophore and the formation of folding conformation. The addition of human serum albumin (HSA) triggered about 40-fold fluorescence enhancements of ADC-IMC-2 and ADC-IMC-6 with 85nm blue-shifts. The probe with longer spacer ADC-IMC-6 exhibited ratiometric fluorescent response toward HSA, and that with shorter linker showed "off-on" fluorescence response to HSA. However, insignificant spectral changes of the reference compounds (ADC-6 and ADC-2) initiated by HSA implied that indomethacin played critical role in the identification of HSA. The competitive assays and molecular docking results reveal that the indomethacin in ADC-IMC-6 could tightly combine at drug site I of HSA. Fluorescence bio-imaging experiments show that both probes could distinguish cancer cells from normal cells.

Multi-Functional Carbon Dots from an Ayurvedic Medicinal Plant for Cancer Cell Bioimaging Applications.

The combination of an Ayurvedic wisdom and nanotechnology may help us to resolve the complex healthcare challenges. A facile and economical one-pot hydrothermal synthesis method has been adopted for preparing a blue fluorescent carbon dots (CDs) with a quantum yield of 15.10% from an Ayurvedic medicinal plant Andrographis paniculata (AP). The Andrographis paniculata derived CDs (AAPCDs) were then characterized using different techniques. Through High Performance Thin Layer Chromatography (HPTLC) profiling of the AP extract and the CDs, it was found that some of the phytoconstituents are retained as such while others may have been converted into their derivatives during the process of formation of CDs. The CDs are designed to possess cellular imaging of human breast carcinoma cells (MCF-7), apart from free radicals sensing and scavenging capabilities. AAPCDs showed minimal cytotoxicity in Multi Drug Resistant clinically isolated strains of gram positive and gram negative bacteria which may be employed for microbiology oriented experiments. These results suggest potential of multi-functional AAPCDs as nano-probes for various pharmaceutical, biomedical and bioengineering applications.

Perylene-Tagged Polycaprolactone Block Copolymers and Their Enzyme-Biodegradable Fluorescent Nanoassemblies for Intracellular Bio-imaging in Cancer Cells

The present investigation reports enzyme-biodegradable perylenebisimide (PBI)-tagged polycaprolactone (PCL) block copolymers, and their aqueous nanoassemblies were employed as probes for intracellular bio-imaging in cancer cells. Bishydroxyl functionalized PBI initiator was tailor-made, and it was employed as initiator for the ring opening polymerization (ROP) methodology to make PBI-tagged tert-butyl ester-substituted polycaprolactone (PBI-BPCLx) block copolymers. The deprotection of these copolymers yielded carboxylic acid-substituted PBI-CPCLx amphiphilic block copolymers. The carboxylic blocks were self-assembled to produce stable red-fluorescent nanoparticles of <150 nm in size in aqueous medium with fluorescent quantum yield of ϕ = 0.25–0.30 suitable for bio-imaging application. In vitro studies confirmed that the aliphatic polyester backbone in the PBI-CPCLx polymer nanoparticles was readily biodegradable by lysosomal enzymes under physiological conditions. Dynamic light scattering, gel permeation ...

Enzyme-Responsive Theranostic FRET Probe Based on l-Aspartic Amphiphilic Polyester Nanoassemblies for Intracellular Bioimaging in Cancer Cells.

The present study reports one of the first attempts on the design and development of an enzymatic-biodegradable theranostic fluorescence resonance energy transfer (FRET) probe constructed on l-amino acid polymer nanoassemblies and demonstrates the proof-of-concept in live cell bioimaging. l-Aspartic acid was converted into amide or carbamate pendants containing bis-carboxylic acid ester monomers, and they were subjected to melt polymerization along with commercial diols to produce amphiphilic aliphatic polyesters. Nanoparticles of size <200 nm were obtained because of self-assembly of these amphiphilic polyesters in an aqueous medium. These nanoparticles exhibited excellent encapsulation capability for green-fluorescent anti-inflammatory drug curcumin (CUR) and highly luminescent red-fluorophore Nile red (NR) to yield a CUR-NR theranostic FRET probe. Detailed photophysical studies were carried out to demonstrate photoexcitation energy transfer from CUR to NR for the occurrence of the FRET phenomena. The theranostic FRET probe was found to be very stable at extracellular environment and underwent biodegradation at the intracellular regions for delivery of the loaded cargoes. As a result, the theranostic FRET probe functioned as turn-on at the extracellular level and became turn-off at the intracellular level under lysosomal enzyme-responsiveness. The polymer nanoparticle was nontoxic to cells, whereas its CUR encapsulated nanoparticle showed relatively good cytotoxicity in breast cancer cell lines. Live cell confocal microscopy studies using lysotracker staining confirmed the colocalization of CUR as well as NR within the polymer nanoparticles in the lysosomes for enzymatic-biodegradation. Selective photoexcitation experiments in the confocal microscope were carried out to study the FRET probe action in cancer cells. Time-dependent FRET imaging directly supported the occurrence of FRET at the intracellular level and enabled the real-time drug release studies. The present approach opens natural resource-based biodegradable theranostic FRET probes for bioimaging application.

Substrate Metabolism-Driven Assembly of High-Quality CdS xSe1- x Quantum Dots in Escherichia coli: Molecular Mechanisms and Bioimaging Application.

Biosynthesis offers opportunities for cost-effective and sustainable production of semiconductor quantum dots (QDs), but is currently restricted by poor controllability on the synthesis process, resulting from limited knowledge on the assembly mechanisms and the lack of effective control strategies. In this work, we provide molecular-level insights into the formation mechanism of biogenic QDs (Bio-QDs) and its connection with the cellular substrate metabolism in Escherichia coli. Strengthening the substrate metabolism for producing more reducing power was found to stimulate the production of several reduced thiol-containing proteins (including glutaredoxin and thioredoxin) that play key roles in Bio-QDs assembly. This effectively diverted the transformation route of the selenium (Se) and cadmium (Cd) metabolic from Cd3(PO4)2 formation to CdS xSe1- x QDs assembly, yielding fine-sized (2.0 ± 0.4 nm), high-quality Bio-QDs with quantum yield (5.2%) and fluorescence lifetime (99.19 ns) far exceeding the existing counterparts. The underlying mechanisms of Bio-QDs crystallization and development were elucidated by density functional theory calculations and molecular dynamics simulation. The resulting Bio-QDs were successfully used for bioimaging of cancer cells and tumor tissue of mice without extra modification. Our work provides fundamental knowledge on the Bio-QDs assembly mechanisms and proposes an effective, facile regulation strategy, which may inspire advances in controlled synthesis and practical applications of Bio-QDs as well as other bionanomaterials.

A Simple and Rapid Fluorescent Probe for Detection of Cr3+ Based on a Coumarin Schiff Base in Aqueous Solution.

A new Cr3+ probe was synthesized using simple Schiff base reaction, which showed prominent fluorescence increasing switch before and after addition Cr3+. The probe proved to have excellent properties, based on both UV-vis absorption and fluorescence spectra. Those properties included high switching performance, good selectivity, and small interference with other metal ions. The fluorescent change mechanism of the probe was attributed to the combined action between the restricted C=N isomerization and the suppression of highly efficient photo-induced electron transfer (PET) process. Moreover, this fluorescence probe for Cr3+ detection also has great potential for bioimaging of cancer cells.

Synthesis of ecofriendly fluorescent carbon dots and their biomedical and environmental applications

ABSTRACTGreen Synthesis of nanoparticles is an emerging field with enormous advantages over conventional synthesis methods. Herein we have reported a green method for the preparation of water soluble polydisperse carbon dots (c-dots) from Cocos nucifera frond pinnae by a modified version of the ‘single step hydrothermal carbonization’. C-dots having blue emission were obtained with this method and we further evaluated the effect of metal ions interactions on c-dots, as a sharp decrease in photoluminescence was observed. The synthesized c-dots were found bioactive against B.subtilis, M. smegmatis and S. aureus as determined by the well diffusion assay. We also explored nanotheranostic applications of c-dots as biosensor matrix in DNA hybridization sensor for pancreatic cancer and in bioimaging of cancer cells. This study demonstrated that c-dots can be explored for numerous biomedical and environmental applications in a variety of fields owing to the cost effective synthesis, biocompatibility and excellent physico-chemical properties.

Real-Time Multimodal Bioimaging of Cancer Cells and Exosomes through Biosynthesized Iridium and Iron Nanoclusters.

Multimodal bioimaging is a powerful tool for visualizing the abnormal state at the target site of the related disease. In this study, we used multimodal imaging techniques such as computed tomography, fluorescence, and magnetic resonance imaging to improve early and precise diagnosis of tumor. Herein, we reported the facile in situ biosynthesis of iridium and iron oxide nanoclusters (NCs) in cancer cells or tumor tissue. These NCs are used as a multimodal bioimaging probe to improve the image sensitivity and specificity toward the tumor. These NCs are applied for the in vivo multimodal imaging in the form of an imaging probe capable of enhancing the sensitivity of the image and specificity toward the tumor tissue. Our observation demonstrates that highly luminescent and magnetic NCs are not only biocompatible but also tumor-targeted because NC formation does not take place in normal cells and tissues. In addition, we isolated exosomes and the biosynthesized NCs internalized within exosomes, and these exosomes can be used as cancer biomarkers.

NIR photo-driven upconversion in NaYF4:Yb,Er/PLGA particles for in vitro bioimaging of cancer cells

Lanthanide-doped fluoride up-converting nanoparticles (UCNPs) represent the new class of imaging contrast agents which hold great potential for overcoming existing problems associated with traditionally used dyes, proteins and quantum dots. In this study, a new kind of hybrid NaYF4:Yb,Er/PLGA nanoparticles for efficient biolabeling were prepared through one-pot solvothermal synthesis route. Morphological and structural characteristics of the as-designed particles were obtained using X-ray powder diffraction (XRPD), scanning and transmission electron microscopy (SEM/TEM), energy dispersive spectroscopy (EDS), Fourier transform infrared (FTIR) and photoluminescence (PL) spectroscopy, while their cytotoxicity as well as up-conversion (UC) labeling capability were tested in vitro toward human gingival cells (HGC) and oral squamous cell carcinoma (OSCC). The results revealed coexistence of the cubic (Fm-3m) and hexagonal (P63/m) phase in spherical and irregularly shaped nanoparticles, respectively. PLGA [Poly(lactic-co-glycolic acid)] ligands attached at the surface of UCNPs particles provide their enhanced cellular uptake and enable high-quality cells imaging through a near-infrared (NIR) laser scanning microscopy (λex = 980 nm). Moreover, the fact that NaYF4:Yb,Er/PLGA UCNPs show low cytotoxicity against HGC over the whole concentration range (10–50 μg/mL) while a dose dependent viability of OSCC is obtained indicates that these might be a promising candidates for targeted cancer cell therapy.

Tuning the Optical Properties of Silicon Quantum Dots via Surface Functionalization with Conjugated Aromatic Fluorophores

Silicon Quantum Dots (SQDs) have recently attracted great interest due to their excellent optical properties, low cytotoxicity, and ease of surface modification. The size of SQDs and type of ligand on their surface has a great influence on their optical properties which is still poorly understood. Here we report the synthesis and spectroscopic studies of three families of unreported SQDs functionalized by covalently linking to the aromatic fluorophores, 9-vinylphenanthrene, 1-vinylpyrene, and 3-vinylperylene. The results showed that the prepared functionalized SQDs had a highly-controlled diameter by HR-TEM, ranging from 1.7–2.1 nm. The photophysical measurements of the assemblies provided clear evidence for efficient energy transfer from the fluorophore to the SQD core. Fӧrster energy transfer is the likely mechanism in these assemblies. As a result of the photogenerated energy transfer process, the emission color of the SQD core could be efficiently tuned and its emission quantum efficiency enhanced. To demonstrate the potential application of the synthesized SQDs for bioimaging of cancer cells, the water-soluble perylene- and pyrene-capped SQDs were examined for fluorescent imaging of HeLa cells. The SQDs were shown to be of low cytotoxicity

Graphene-Based Nanomaterials for Theranostic Applications

Graphene and graphene-based nanomaterials such as graphene oxide (GO), reduced graphene oxide (rGO) and graphene quantum dots (GQDs) have gained a lot of attention from diverse scientific fields for applications in sensing, catalysis, nanoelectronics, material engineering, energy storage and biomedicine due to its unique structural, optical, electrical and mechanical properties. Graphene-based nanomaterials emerge as a novel class of nanomedicine for cancer therapy for several reasons. Firstly, its structural properties like high surface area and aromaticity enables easy loading of hydrophobic drugs. Secondly, presence of oxygen containing functional groups improve its physiological stability and also act as site for biofunctionalization. Thirdly, its optical absorption in the NIR region enable them to act as photoagents for photothermal and photodynamic therapies of cancer, both in vitro and in vivo. Finally, its intrinsic fluorescence property helps in bioimaging of cancer cells. Overall, graphene-based nanomaterials can act as agents for developing multifunctional theranostic platforms for carrying out more efficient detection and treatment of cancers. This review provides a detailed summary of the different applications of graphene-based nanomaterials in drug delivery, nucleic acid delivery, phototherapy, bioimaging and theranostics.

Ca2+ Induced Crosslinking of AIE-Active Polyarylene Ether Nitrile into Fluorescent Polymeric Nanoparticles for Cellular Bioimaging.

Biocompatible fluorescent polymeric nanoparticles (FPNs) are promising luminescent probes in cellular bioimaging, while the fabrication of high-quantum-yield FPN using nonconjugated heterochain polymers derived from step-growth polymerization is still in its infancy. Herein, the nonconjugated polyarylene ether nitrile (PEN) is endowed with aggregation-induced emission (AIE) feature by incorporation of an AIEgen named of 1,2-di(4-hydroxyphenyl)-1,2-diphenylethene into macromolecular backbone. Furthermore, the AIE-active PEN is crosslinked into water soluble fluorescent nanospheres showing good biocompatibility and strong emission ≈480 nm with a quantum yield of 21% in the presence of Ca2+ , which allows the successful bioimaging of cancer cells. Due to the facile fabrication of FPNs and their effective bioimaging performance, the current work will open the way for the biomedical applications of various high performance polyarylene ethers.

Fluorescent-Tagged Biodegradable Polycaprolactone Block Copolymer FRET Probe for Intracellular Bioimaging in Cancer Cells.

The present investigation reports a new fluorophore-tagged biodegradable polycaprolactone (PCL) block copolymer FRET-probe for intracellular imaging in cancer therapy. A hydroxyl functionalized π-conjugated oligo-phenylenevinylene (OPV) chromophore was tailor-made, and it was incorporated in a t-butyl ester substituted polycaprolactone block copolymer via ring opening polymerization. This blue-luminescent OPV-PCL triblock self-assembled as <200 nm spherical nanoparticles (FRET donor), and it encapsulated water insoluble Nile red (NR, FRET acceptor) to yield an OPV-NR FRET probe. Selective photo excitation of the OPV chromophore in block nanoassemblies enabled the excitation energy transfer from the OPV to NR and facilitated the efficient FRET process in aqueous medium. Time-correlated fluorescent decay dynamics and detailed photophysical studies were carried out to estimate the Förster distance, donor-acceptor distance, and the excitation energy transfer efficiency. These parameters confirmed the occurrence of the FRET process within the confined nanoparticle environment. The PCL chains in the FRET probe were susceptible to enzymatic biodegradation in intracellular environments, and the degradation process controlled the FRET on/off mechanism. Cytotoxicity studies revealed that the FRET probe was biocompatible and nontoxic to cells, and the FRET-probe was found to be readily taken up by the cancer cells, and it was internalized in the cytoplasm and peri-nuclear environment. Selective photoexcitation of the OPV chromophore in a confocal microscope exhibited dual emission from the FRET probe. The cancer cells exhibited blue luminescence (self-emission) with respect to the OPV chromophore (in the blue channel) and bright red-luminescence from the NR dye followed by the FRET process at the cellular level (in the red channel). The dual luminescence characteristics, biodegradation and biocompatibility, make the newly designed PCL-OPV-NR FRET probe an excellent biomedical nanodevice for bioimaging applications, and the proof-of-concept was established in cervical (HeLa) and breast cancer (MCF 7) cell lines.

π-Conjugate Fluorophore-Tagged and Enzyme-Responsive l-Amino Acid Polymer Nanocarrier and Their Color-Tunable Intracellular FRET Probe in Cancer Cells.

The present investigation accounts one of the first example of enzyme-responsive and π-conjugate-tagged l-amino acid amphiphilic polymer and their fluorescence resonance energy transfer (FRET) probes for color-tunable intracellular bioimaging in cancer cells. Melt polymerizable oligo-phenylenevinylene (OPV) π-conjugated diol was tailor-made and subjected to thermo-selective melt transesterification reaction with multifunctional l-aspartic acid monomer to yield OPV-tagged amphiphilic luminescent polyesters. These amphiphilic polyesters self-assembled through strong aromatic π-π stacking and hydrophilic/hydrophobic noncovalent forces into <200 nm size blue-luminescent nanoparticles in aqueous medium. The OPV-tagged polymer nanoparticles served as FRET donor and encapsulated water insoluble Nile Red (NR) fluorophore as a FRET acceptor. Detail photophysical studies revealed that both the OPV and NR were confined within Förster distance in the polymer nanocontainer and the nanodomains provided appropriate geometry for efficient excitation energy transfer from OPV to NR. Cytotoxicity studies in breast cancer (MCF 7), cervical cancer (HeLa) and normal (Wild-type MEF) cell lines revealed that both the nascent luminescent OPV nanoparticles and OPV-NR FRET probes were nontoxic to cells up to 100 μg/mL. Confocal microscope images confirmed the efficient transportation of polymer and FRET probes across the cell membranes and their preferable accumulation in the cytoplasm of the cells. Lysosomal tracker assisted live cell imaging provided direct evidence for the localization of the polymer nanoparticles at the lysosomal compartments in the cytoplasm. In vitro enzyme-responsive studies revealed that the aliphatic polyester backbone in the polymer nanoparticles was readily biodegradable by lysosomal enzymes like esterase, chymotrypsin, trypsin, and also redox GSH species in the cytoplasm. Selective photoexcitation in confocal microscope exhibited bright OPV blue-luminescence and strong red-emission from NR followed by the excitation energy transfer and occurrence of FRET process at the intracellular environment in cancer cell lines. Both the polymer design and the biodegradable polymer FRET concept are completely new; thus, the present approach opens up new platform of research opportunities for natural l-amino acid based luminescent polymer probes for color-tunable bioimaging in cancer cells.

Two-Photon Fluorescent Molybdenum Disulfide Dots for Targeted Prostate Cancer Imaging in the Biological II Window.

Molybdenum disulfide (MoS2) quantum dots (QDs) derived from this two-dimensional (2D) transition metal dichalcogenide are emerging zero-dimensional materials that possess very good optical properties. Bioimaging using light in the biological II window (950–1350 nm) is a next-generation approach that will allow clinicians to achieve deeper tissue imaging with better image contrast and reduced phototoxicity and photobleaching. This article reports the development of a water-soluble, zero-dimensional antibody-conjugated transition metal dichalcogenide MoS2 QD-based two-photon luminescence (TPL) probe for the targeted bioimaging of cancer cells in the biological II window. The data indicates that MoS2 QDs exhibit an extremely high two-photon absorption cross-section (σ = 58960 GM) and two-photon brightness (4.7 × 103 GM) because of the quantum confinement and edge effects. Experimental data show that anti-PSMA antibody-attached MoS2 QDs can be used for selective two-photon imaging of live prostate cancer cells using 1064 nm light because of the high two-photon brightness, very good photostability, and very good biocompatibility of these MoS2 QDs. The data demonstrate that the bioconjugated MoS2 QDs can distinguish targeted and nontargeted cells. This study illuminates the high two-photon brightness mechanism of MoS2 QDs and provides a zero-dimensional transition metal dichalcogenide-based selective TPL agent for high-efficiency live cell imaging.