Sugar-quantum dot conjugates for a selective and sensitive detection of lectins

Simple engineering of hybrid cellulose nanocrystal-gold nanoparticles results in a functional glyconanomaterial with biomolecular recognition properties

Cellulose nanocrystal and gold nanoparticles are assembled, in a unique way, to yield a novel modular glyconanomaterial whose surface is then easily engineered with one or two different headgroups, by exploiting a robust click chemistry route. We demonstrate the potential of this approach by conjugating monosaccharide headgroups to the glyconanomaterial and show that the sugars retain their binding capability to C-type lectin receptors, as also directly visualized by cryo-TEM.

Multimodal Radiobioconjugates of Magnetic Nanoparticles Labeled with 44Sc and 47Sc for Theranostic Application

This study was performed to synthesize multimodal radiopharmaceutical designed for the diagnosis and treatment of prostate cancer. To achieve this goal, superparamagnetic iron oxide (SPIO) nanoparticles were used as a platform for targeting molecule (PSMA-617) and for complexation of two scandium radionuclides, 44Sc for PET imaging and 47Sc for radionuclide therapy. TEM and XPS images showed that the Fe3O4 NPs have a uniform cubic shape and a size from 38 to 50 nm. The Fe3O4 core are surrounded by SiO2 and an organic layer. The saturation magnetization of the SPION core was 60 emu/g. However, coating the SPIONs with silica and polyglycerol reduces the magnetization significantly. The obtained bioconjugates were labeled with 44Sc and 47Sc, with a yield higher than 97%. The radiobioconjugate exhibited high affinity and cytotoxicity toward the human prostate cancer LNCaP (PSMA+) cell line, much higher than for PC-3 (PSMA-) cells. High cytotoxicity of the radiobioconjugate was confirmed by radiotoxicity studies on LNCaP 3D spheroids. In addition, the magnetic properties of the radiobioconjugate should allow for its use in guide drug delivery driven by magnetic field gradient.

Engineering Carbohydrate-Based Particles for Biomedical Applications: Strategies to Construct and Modify

Carbohydrate-based micro/nanoparticles have gained significant attention for various biomedical applications such as targeted/triggered/controlled drug delivery, bioimaging, biosensing, etc., because of their prominent characteristics like biocompatibility, biodegradability, hydrophilicity, and nontoxicity as well as nonimmunogenicity. Most importantly, the ability of the nanoparticles to recognize specific cell sites by targeting cell surface receptors makes them a promising candidate for designing a targeted drug delivery system. These particles may either comprise polysaccharides/glycopolymers or be integrated with various polymeric/inorganic nanoparticles such as gold, silver, silica, iron, etc., to reduce the toxicity of the inorganic nanoparticles and thus facilitate their cellular insertion. Various synthetic methods have been developed to fabricate carbohydrate-based or carbohydrate-conjugated inorganic/polymeric nanoparticles. In this review, we have highlighted the recently developed synthetic approaches to afford carbohydrate-based particles along with their significance in various biomedical applications.

Glyco-nanoparticles: New drug delivery systems in cancer therapy

Cancer is known as one of the most common diseases that are associated with high mobility and mortality in the world. Despite several efforts, current cancer treatment modalities often are highly toxic and lack efficacy and specificity. However, the application of nanotechnology has led to the development of effective nanosized drug delivery systems which are highly selective for tumors and allow a slow release of active anticancer agents. Different Nanoparticles (NPs) such as the silicon-based nano-materials, polymers, liposomes and metal NPs have been designed to deliver anti-cancer drugs to tumor sites. Among different drug delivery systems, carbohydrate-functionalized nanomaterials, specially based on their multi-valent binding capacities and desirable bio-compatibility, have attracted considerable attention as an excellent candidate for controlled release of therapeutic agents. In addition, these carbohydrate functionalized nano-carriers are more compatible with construction of the intracellular delivery platforms like the carbohydrate-modified metal NPs, quantum dots, and magnetic nano-materials. In this review, we discuss recent research in the field of multifunctional glycol-nanoparticles (GNPs) intended for cancer drug delivery applications.

An array consisting of glycosylated quantum dots conjugated to MoS2 nanosheets for fluorometric identification and quantitation of lectins and bacteria

A fluorescent array based on the use of saccharide-functionalized multicolored quantum dots (s-QDs) and of 4-mercaptophenylboronic acid-functionalized MoS₂ nanosheets (PBA-MoS₂) was constructed for multiple identification and quantitation of lectins and bacteria. In this array, the fluorescence of the s-QDs is quenched by the PBA-MoS₂ nanosheets. In the presence of multiple lectins, s-QDs differentially detach from the surface of PBA-MoS₂ nanosheets, producing distinct fluorescence response patterns due to both quenching and enhancement of fluorescence. By analyzing the fluorescence responses with linear discriminant analysis, multiple lectins and bacteria were accurately identified with 100% accuracy. The limits of detection of Concanavalin A, Pisum sativum agglutinin, Peanut agglutinin, and Ricius communis I agglutinin are as low as 3.7, 8.3, 4.2 and 3.9 nM, respectively. The array has further been evidenced to be potent for distinguishing and quantifying different bacterial species by recognizing their surface lectins. The detection limits of Escherichia coli and Enterococcus faecium are 87 and 66 cfu mL^-1, respectively. Graphical abstract Schematic of a fluorometric array based on the use of saccharides-functionalized quantum dots (s-QDs) and 4-mercaptophenylboronic acid-functionalized MoS₂ (PBA- MoS₂) nanosheets. This array was successfully applied to simultaneously analysis of lectins, bacteria in real samples with high sensitivity and accuracy.

A Pilot Study Into the Use of FDG-mNP as an Alternative Approach in Neuroblastoma Cell Hyperthermia

Herein, we present a pilot study concerning the use of fluorodeoxy glucose conjugated magnetite nanoparticles (FDG-mNP) as a potential agent in magnetic nanoparticle mediated neuroblastoma cancer cell hyperthermia. This approach makes use of the 'Warburg effect', utilizing the fact that cancer cells have a higher metabolic rate than normal cells. FDG-mNP were synthesized, then applied to the SH-SY5Y neuroblastoma cancer cell line and exposed to an ac magnetic field. 3D Calorimetry was performed on the FDG-mNP compound. Simulations were performed using SEMCAD X software using Thelonious, (an anatomically correct male child model) in order to understand more about the end requirements with respect to cancer cell destruction. We investigated FDG-mNP mediated neuroblastoma cytotoxicity in conjunction with ac magnetic field exposure. Results are presented for 3D FDG-mNP SAR _mnp (10.86 ± 0.99 W/g of particles) using a therapeutic dose of 0.83 mg/ mL. Human model simulations suggest that 43 W/kg SAR _Theo would be required to obtain 42 °C within the centre of a liver tumor (Tumor size, bounding box x = 64, y = 61, z = 65 [mm]), and that the temperature distribution is inhomogeneous within the tumor. Our study suggests that this approach could potentially be used to increase the temperature within cells that would result in cancer cell death due to hyperthermia. Further development of this research will also involve using whole tumors removed from living organisms in conjunction with magnetic resonance imaging and positron emission tomography.

Glyconanomaterials for biosensing applications

Nanomaterials constitute a class of structures that have unique physiochemical properties and are excellent scaffolds for presenting carbohydrates, important biomolecules that mediate a wide variety of important biological events. The fabrication of carbohydrate-presenting nanomaterials, glyconanomaterials, is of high interest and utility, combining the features of nanoscale objects with biomolecular recognition. The structures can also produce strong multivalent effects, where the nanomaterial scaffold greatly enhances the relatively weak affinities of single carbohydrate ligands to the corresponding receptors, and effectively amplifies the carbohydrate-mediated interactions. Glyconanomaterials are thus an appealing platform for biosensing applications. In this review, we discuss the chemistry for conjugation of carbohydrates to nanomaterials, summarize strategies, and tabulate examples of applying glyconanomaterials in in vitro and in vivo sensing applications of proteins, microbes, and cells. The limitations and future perspectives of these emerging glyconanomaterials sensing systems are furthermore discussed.

Carbohydrates in Supramolecular Chemistry

Carbohydrates are involved in a variety of biological processes. The ability of sugars to form a large number of hydrogen bonds has made them important components for supramolecular chemistry. We discuss recent advances in the use of carbohydrates in supramolecular chemistry and reveal that carbohydrates are useful building blocks for the stabilization of complex architectures. Systems are presented according to the scaffold that supports the glyco-conjugate: organic macrocycles, dendrimers, nanomaterials, and polymers are considered. Glyco-conjugates can form host-guest complexes, and can self-assemble by using carbohydrate-carbohydrate interactions and other weak interactions such as π-π interactions. Finally, complex supramolecular architectures based on carbohydrate-protein interactions are discussed.

Glyconanoparticles for colorimetric bioassays

Carbohydrate molecules are involved in many of the cellular processes that are important for life. By combining the specific analyte targeting of carbohydrates with the multivalent structure and change of solution colour as a consequence of plasmonic interactions with the aggregation of metal nanoparticles, glyconanoparticles have been used extensively for the development of bioanalytical assays. The noble metals used to create the nanocore, the methodologies used to assemble the carbohydrates on the nanoparticle surface, the carbohydrate chosen for each specific target, the length of the tether that separates the carbohydrate from the nanocore and the density of carbohydrates on the surface all impact on the structural formation of metal based glyconanoparticles. This tutorial review highlights these key components, which directly impact on the selectivity and sensitivity of the developed bioassay, for the colorimetric detection of lectins, toxins and viruses.

Probing cell-surface carbohydrate binding proteins with dual-modal glycan-conjugated nanoparticles

Dual-modal fluorescent magnetic glyconanoparticles have been prepared and shown to be powerful in probing lectins displayed on pathogenic and mammalian cell surfaces. Blood group H1- and Le(b)-conjugated nanoparticles were found to bind to BabA displaying Helicobacter pylori, and Le(a)- and Le(b)-modified nanoparticles are both recognized by and internalized into DC-SIGN and SIGN-R1 expressing mammalian cells via lectin-mediated endocytosis. In addition, glyconanoparticles block adhesion of H. pylori to mammalian cells, suggesting that they can serve as inhibitors of infection of host cells by this pathogen. It has been also shown that owing to their magnetic properties, glyconanoparticles are useful tools to enrich lectin expressing cells. The combined results indicate that dual-modal glyconanoparticles are biocompatible and that they can be employed in lectin-associated biological studies and biomedical applications.

Glyconanoparticles and their interactions with lectins

Glyconanoparticles and their interactions with lectins.

A biosensing platform for sensitive detection of concanavalin A based on fluorescence resonance energy transfer from CdTe quantum dots to graphene oxide

The sandwich method can detect different lectins simply by exchanging the carbohydrates functionalized on the quantum dots and graphene oxide.

Glyconanomaterials: Emerging applications in biomedical research

Carbohydrates constitute the most abundant organic matter in nature, serving as structural components and energy sources, and mediating a wide range of cellular activities. The emergence of nanomaterials with distinct optical, magnetic, and electronic properties has witnessed a rapid adoption of these materials for biomedical research and applications. Nanomaterials of various shapes and sizes having large specific surface areas can be used as multivalent scaffolds to present carbohydrate ligands. The resulting glyconanomaterials effectively amplify the glycan-mediated interactions, making it possible to use these materials for sensing, imaging, diagnosis, and therapy. In this review, we summarize the synthetic strategies for the preparation of various glyconanomaterials. Examples are given where these glyconanomaterials have been used in sensing and differentiation of proteins and cells, as well as in imaging glycan-medicated cellular responses.

A guide into glycosciences: How chemistry, biochemistry and biology cooperate to crack the sugar code

BACKGROUND

The most demanding challenge in research on molecular aspects within the flow of biological information is posed by the complex carbohydrates (glycan part of cellular glycoconjugates). How the 'message' encoded in carbohydrate 'letters' is 'read' and 'translated' can only be unraveled by interdisciplinary efforts.

SCOPE OF REVIEW

This review provides a didactic step-by-step survey of the concept of the sugar code and the way strategic combination of experimental approaches characterizes structure-function relationships, with resources for teaching.

MAJOR CONCLUSIONS

The unsurpassed coding capacity of glycans is an ideal platform for generating a broad range of molecular 'messages'. Structural and functional analyses of complex carbohydrates have been made possible by advances in chemical synthesis, rendering production of oligosaccharides, glycoclusters and neoglycoconjugates possible. This availability facilitates to test the glycans as ligands for natural sugar receptors (lectins). Their interaction is a means to turn sugar-encoded information into cellular effects. Glycan/lectin structures and their spatial modes of presentation underlie the exquisite specificity of the endogenous lectins in counterreceptor selection, that is, to home in on certain cellular glycoproteins or glycolipids.

GENERAL SIGNIFICANCE

Understanding how sugar-encoded 'messages' are 'read' and 'translated' by lectins provides insights into fundamental mechanisms of life, with potential for medical applications.

The application of CdSe quantum dots with multicolor emission as fluorescent probes for cell labeling

Herein, highly luminescent CdSe quantum dots (QDs) with emissions from the blue to the red region of visible light were synthesized by using a simple method. The emission range of the CdSe QDs could be tuned from λ=503 to 606 nm by controlling the size of the CdSe QDs. Two amino acids, L-tryptophan (L-Trp) and L-arginine (L-Arg), were used as coating agents. The quantum yield (QY) of CdSe QDs (green color) with an optimized thickness could reach up to 52 %. The structures and compositions of QDs were examined by using X-ray diffraction (XRD) and transmission electron microscopy (TEM). Optical properties were studied by using UV/Vis and photoluminescence (PL) spectroscopy and a comparison was made between uncoated and coated CdSe QDs. The amino acid-modified β-cyclodextrin (CD)-coated CdSe QDs presented lower cytotoxicity to cells for 48 h. Furthermore, amino acid-modified β-CD-coated green CdSe QDs in HepG2 cells were assessed by using confocal laser scanning fluorescence microscopy. The results showed that amino acid-modified β-CD-coated green CdSe QDs could enter tumor cells efficiently and indicated that biomolecule-coated QDs could be used as a potential fluorescent probe.

Cadmium-free sugar-chain-immobilized fluorescent nanoparticles containing low-toxicity ZnS-AgInS2 cores for probing lectin and cells

Sugar chains play a significant role in various biological processes through sugar chain-protein and sugar chain-sugar chain interactions. To date, various tools for analyzing sugar chains biofunctions have been developed. Fluorescent nanoparticles (FNPs) functionalized with carbohydrate, such as quantum dots (QDs), are an attractive imaging tool for analyzing carbohydrate biofunctions in vitro and in vivo. Most FNPs, however, consist of highly toxic elements such as cadmium, tellurium, selenium, and so on, causing problems in long-term bioimaging because of their cytotoxicity. In this study, we developed cadmium-free sugar-chain-immobilized fluorescent nanoparticles (SFNPs) using ZnS-AgInS2 (ZAIS) solid solution nanoparticles (NPs) of low or negligible toxicity as core components, and investigated their bioavailability and cytotoxicity. SFNPs were prepared by mixing our originally developed sugar-chain-ligand conjugates with ZAIS/ZnS core/shell NPs. In binding experiments with lectin, the obtained ZAIS/ZnS SFNPs interacted with an appropriate lectin to give specific aggregates, and their binding interaction was visually and/or spectroscopically detected. In addition, these SFNPs were successfully utilized for cytometry analysis and cellular imaging in which the cell was found to possess different sugar-binding properties. The results of the cytotoxicity assay indicated that SFNPs containing ZAIS/ZnS have much lower toxicity than those containing cadmium. These data strongly suggest that our designed SFNPs can be widely utilized in various biosensing applications involved in carbohydrates.

Multivalent glycosylated nanoparticles for studying carbohydrate–protein interactions

Glyconanoparticles decorated with multiple copies of various biologically relevant carbohydrates serve as scaffolds for protein binding assay, molecular imaging, targeted therapy, and bacterium detection.

Simultaneous determination of concanavalin A and peanut agglutinin by dual-color quantum dots

In this work, we designed a novel detection strategy to realize simultaneous determination of multiplex lectin by labeling glucosamine (G1) and galactosamine (G2) with different-colored semiconductor quantum dots (QDs). On the basis of the agglutination of the aminosugar-labeled QDs induced by the exclusive binding between the lectin and sugar on the QDs surfaces, the fluorescence emission of the QDs supernatant after centrifugation decreased with relevant lectin concentration [i.e., when concanavalin A (Con A) exists alone], only green color fluorescence emission from QDs-G1 supernatant decreased, so it is peanut agglutinin (PNA) and red color fluorescence emission from QDs-G2. Moreover, since QDs can be simultaneously excited with multiple fluorescence colors and have a larger Stokes shift than organic fluorophores, when both Con A and PNA are present in the sample, both of the green and red color fluorescence emission from QDs-G1 and QDs-G2 supernatant would decrease, thus realizing the simultaneous determination of Con A and PNA. The detection limits of Con A and PNA are 0.30 and 0.18 nM (3σ), respectively. Furthermore, the present detection method not only can determine the protein/lectins by fluorescence spectral method but also can realize visualization detection by UV lamp illumination. To the best of our knowledge, this is the first report of such analytical method in multiple and simultaneous lectin detection.

Glycoconjugated amphiphilic polymers via click-chemistry for the encapsulation of quantum dots

Herein, we present a strategy for the glycoconjugation of nanoparticles (NPs), with a special focus on fluorescent quantum dots (QDs), recently described by us as "preassembly" approach. Therein, prior to the encapsulation of diverse nanoparticles by an amphiphilic poly(isoprene)-b-poly(ethylene glycol) diblock copolymer (PI-b-PEG), the terminal PEG appendage was modified by covalently attaching a carbohydrate moiety using Huisgen-type click-chemistry. Successful functionalization was proven by NMR spectroscopy. The terminally glycoconjugated polymers were subsequently used for the encapsulation of QDs in a phase transfer process, which fully preserved fluorescence properties. Binding of these nanoconstructs to the lectin Concanavalin A (Con A) was studied via surface plasmon resonance (SPR). Depending on the carbohydrate moiety, namely, D-manno-heptulose, D-glucose, D-galactose, 2-deoxy-2-{[methylamino)carbonyl]amino}-D-glucopyranose ("des(nitroso)-streptozotocin"), or D-maltose, the glycoconjugated QDs showed enhanced affinity constants due to multivalent binding effects. None of the constructs showed toxicity from 0.001 to 1 μM (particle concentration) using standard WST and LDH assays on A549 cells.

A new strategy for intracellular delivery of enzyme using mesoporous silica nanoparticles: superoxide dismutase

We developed mesoporous silica nanoparticle (MSN) as a multifunctional vehicle for enzyme delivery. Enhanced transmembrane delivery of a superoxide dismutase (SOD) enzyme embedded in MSN was demonstrated. Conjugation of the cell-penetrating peptide derived from the human immunodeficiency virus 1 (HIV) transactivator protein (TAT) to mesoporous silica nanoparticle is shown to be an effective way to enhance transmembrane delivery of nanoparticles for intracellular and molecular therapy. Cu,Zn-superoxide dismutase (SOD) is a key antioxidant enzyme that detoxifies intracellular reactive oxygen species, ROS, thereby protecting cells from oxidative damage. In this study, we fused a human Cu,Zn-SOD gene with TAT in a bacterial expression vector to produce a genetic in-frame His-tagged TAT-SOD fusion protein. The His-tagged TAT-SOD fusion protein was expressed in E. coli using IPTG induction and purified using FMSN-Ni-NTA. The purified TAT-SOD was conjugated to FITC-MSN forming FMSN-TAT-SOD. The effectiveness of FMSN-TAT-SOD as an agent against ROS was investigated, which included the level of ROS and apoptosis after free radicals induction and functional recovery after ROS damage. Confocal microscopy on live unfixed cells and flow cytometry analysis showed characteristic nonendosomal distribution of FMSN-TAT-SOD. Results suggested that FMSN-TAT-SOD may provide a strategy for the therapeutic delivery of antioxidant enzymes that protect cells from ROS damage.

Glyco-β-cyclodextrin capped quantum dots: synthesis, cytotoxicity and optical detection of carbohydrate-protein interactions

Highly fluorescent water soluble glyco-quantum dots were synthesized using a sonochemical procedure. The synthetic approach is based on specific host-guest interactions between β-cyclodextrin (β-CD) and trioctylphosphine oxide (TOPO) surfactant on quantum dots. The modified QDs were analyzed by a combination of FT-IR, (1)H-NOESY NMR spectroscopy and by TEM. The high sugar density on QDs resulted in selective colloidal aggregation with ConcanavalinA (ConA), Galanthus nivalis lectin (GNA) and Peanut agglutinin (PNA) lectins. Subsequently, in vitro studies indicated that β-CD modification of QDs enabled good cell viability of human hepatocellular carcinoma cell line (HepG2) cells. Finally, flow cytometry and confocal imaging studies revealed that βCDgal capped QDs undergo preferential binding with HepG2 cells. These results clearly demonstrate that β-CD capped QDs could be a promising candidate for further carbohydrate-based biomedical applications.

Study of carbohydrate-protein interactions using glyco-QDs with different fluorescence emission wavelengths

QDs with different fluorescence emission wavelengths were coated with galactose, glucose, and lactose respectively. The formulas of glyco-QDs were determined by NMR and ICP-OES, and the interactions between glyco-QDs and PNA lectin were investigated by SPR. The results showed that multivalent presentation achieved by using QDs as the scaffold is an effective way to enhance the carbohydrate-protein interactions. The K(D) for the interaction of PNA with multivalent glyco-QDs is over 3 × 10(6)-fold lower than those with the same free sugars. The specific recognition for the sugar coated on the QDs by lectin is maintained. These sugar-coated QDs could be used as a fluorescent probe to label and identify glycoproteins.

Synthetic polymer nanoparticle-polysaccharide interactions: a systematic study

The interaction between synthetic polymer nanoparticles (NPs) and biomacromolecules (e.g., proteins, lipids, and polysaccharides) can profoundly influence the NPs fate and function. Polysaccharides (e.g., heparin/heparin sulfate) are a key component of cell surfaces and the extracelluar matrix and play critical roles in many biological processes. We report a systematic investigation of the interaction between synthetic polymer nanoparticles and polysaccharides by ITC, SPR, and an anticoagulant assay to provide guidelines to engineer nanoparticles for biomedical applications. The interaction between acrylamide nanoparticles (~30 nm) and heparin is mainly enthalpy driven with submicromolar affinity. Hydrogen bonding, ionic interactions, and dehydration of polar groups are identified to be key contributions to the affinity. It has been found that high charge density and cross-linking of the NP can contribute to high affinity. The affinity and binding capacity of heparin can be significantly diminished by an increase in salt concentration while only slightly decreased with an increase of temperature. A striking difference in binding thermodynamics has been observed when the main component of a polymer nanoparticle is changed from acrylamide (enthalpy driven) to N-isopropylacryalmide (entropy driven). This change in thermodynamics leads to different responses of these two types of polymer NPs to salt concentration and temperature. Select synthetic polymer nanoparticles have also been shown to inhibit protein-heparin interactions and thus offer the potential for therapeutic applications.

Enabling biomedical research with designer quantum dots

Quantum Dots (QDs) are a new class of semiconductor nanoparticulate luminophores, which are actively researched for novel applications in biology and nanomedicine. In this review, the recent progress in the design and applications of QD labels for in vitro and in vivo imaging of cells is presented. Surface chemical engineering of hydrophobic QDs is required to render them water soluble and biocompatible. Further surface modification and attachment of bioactive molecules to the surface of QDs, such as peptides, aptamers, or antibodies are intensively explored for targeted imaging of living cells, and disease states in animals. Specially designed surface coatings can drastically decrease nonspecific interactions between QDs and cells, minimize degradation of QDs under in vivo physiological conditions, reduce the cytotoxicity of QDs, and prolong circulation lifetimes in animals. New generations of QD probes are also promising for imaging cellular processes at the single-molecule level. Ultimately, QDs as components of complex therapeutic nanosystems are poised to contribute significantly to the field of personalized medicine.

Overview of stabilizing ligands for biocompatible quantum dot nanocrystals

Luminescent colloidal quantum dots (QDs) possess numerous advantages as fluorophores in biological applications. However, a principal challenge is how to retain the desirable optical properties of quantum dots in aqueous media while maintaining biocompatibility. Because QD photophysical properties are directly related to surface states, it is critical to control the surface chemistry that renders QDs biocompatible while maintaining electronic passivation. For more than a decade, investigators have used diverse strategies for altering the QD surface. This review summarizes the most successful approaches for preparing biocompatible QDs using various chemical ligands.

Gold nanoparticle probes: design and in vitro applications in cancer cell culture

A new architecture has been designed by the conjugation of [(18)F]2-fluoro-2-deoxy-D-glucose ((18)F-FDG), gold nanoparticles (AuNPs), and anti-metadherin (Anti-MTDH) antibody which is specific to the metadherin (MTDH) over-expressed on the surface of breast cancer cells. Mannose triflate molecule is used as a precursor for synthesis of (18)F-FDG by nucleophilic fluorination. For the conjugation of (18)F-FDG and AuNPs, cysteamine was first bound to mannose triflate (Man-CA) before synthesizing of (18)F-FDG which has cysteamine sides ((18)FDG-CA). Then, (18)FDG-CA was reacted with HAuCl(4) to obtain AuNPs and with NaBH(4) for reduction of AuNPs. At the end of this procedure, AuNPs were conjugated to (18)F-FDG via disulphide bonds ((18)FDG-AuNP). For the conjugation of Anti-MTDH, 1,1'-carbonyl diimidazol (CDI) was bound to the (18)FDG-AuNP, and Anti-MTDH was conjugated via CDI ((18)FDG-AuNP-Anti-MTDH). This procedure was also performed by using Na(19)F to obtain non-radioactive conjugates ((19)FDG-AuNP-Anti-MTDH). Scanning electron microscopy (SEM) images demonstrated that synthesized particles were in nano sizes. (18)FDG-AuNP-Anti-MTDH conjugate was characterized and used as a model probe containing both radioactive and optical labels together as well as the biological target. The (18)FDG-AuNP-Anti-MTDH conjugate was applied to MCF7 breast cancer cell line and apoptotic cell ratio was found to be increasing from 2% to 20% following the treatment. Hence, these results have promised an important application potential of this conjugate in cancer research.

Continuous-flow reactor-based synthesis of carbohydrate and dihydrolipoic acid-capped quantum dots

A detailed protocol for the large-scale synthesis of carbohydrate and dihydrolipoic acid (DHLA)-coated CdSe/ZnS and CdTe/ZnS nanoparticles using continuous flow reactors is described here. Three continuous flow microreaction systems, operating at three different temperatures, are used for the synthesis of mannose-, galactose- or DHLA-functionalized quantum dots (QDs). In the first step of synthesis, the CdSe and CdTe nanoparticles are prepared. The size and spectral properties of the CdSe core of the nanoparticles are controlled by adjustment of the residence time and the temperature. As a second step, the zinc sulfide capping under homogenous conditions is carried out at a substantially lower temperature than is required for nanoparticle growth in batch processes. Finally, the trioctylphosphine/oleic acid ligand is effectively replaced with either carbohydrate PEG-thiol moieties or DHLA at 60 °C. This new protocol allows the synthesis of biologically active fluorescent QDs in 4 d.