Citrate Synthesis of Gold Nanoparticles - YouTube

Pyridyl disulfide linkers include cleavable disulfide bonds, which facilitates a quantitative evaluation of the reaction efficiency. Jon . calculated the concentration of surface-bound peptide molecules on the nanoparticles by quantifying the released pyridine-2-thione []. In an effort to develop integrin-targeted iron oxide nanoparticles as theranostic agents, amine-modified iron oxide nanoparticles were synthesized, and SPDP was added to convert the primary amine groups on the nanoparticles to sulfhydryl-reactive pyridyldisulfide groups. Conjugation between the thiol group-containing cyclic RGD peptides and the SPDP-activated nanoparticles produced pyridine-2-thione, which was immediately collected by spin filtering (at 100 K). The immobilized cRGD molecules were quantified based on the ultraviolet (UV) absorbance at 343 nm of the collected pyridine-2-thione filtrate, indicating that the average number of conjugated cRGD peptides on each nanoparticle was 0.39 wt%. This linker is useful for enhancing the intracellular gene silencing properties of siRNA. Bhatia . studied the gene-silencing efficacy of siRNA-conjugated QDs using cleavable (sulfo-LC-SPDP) or noncleavable (sulfo-SMCC) cross-linkers []. They immobilized thiol-modified siRNA specific for EGFP to amine-functionalized QDs via sulfo-LC-SPDP or sulfo-SMCC linkers and quantified the EGFP fluorescence intensity. The siRNA attached QDs via the sulfo-LC-SPDP linker provided greater silencing efficiency than those attached via the sulfo-SMCC linker. The cleavable disulfide cross-linker released siRNA from the nanoparticles into the intracellular reducing environment, which affected the interactions between the siRNA and the RNA induced silencing complex (RISC), which is necessary for gene knockdown.

8/2/2012 · Citrate Synthesis of Gold ..

All these studiessuggest formation of stable quercetin-gold nanoparticle complex.

since small nanoparticles of gold are red

Targeting moieties are classified as proteins (mainly antibodies and their fragments), peptides, nucleic acids (aptamers), small molecules, or others (vitamins or carbohydrates). Although monoclonal antibodies (mAbs) have been widely used as escort molecules for the targeted delivery of nanoparticles, several limitations including large size and difficulty in conjugation to nanoparticles have hampered their uses. Thus, other smaller-sized ligands including peptides have attracted greater attention these days. This section will discuss the types of targeting moieties that may be used for decorating multifunctional nanoparticles, as well as their potential benefits and drawbacks.

Small Gold Nanoparticles Synthesized with Sodium Citrate ..

Wei and Gao used a single chain anti-prostate stem cell antigen (PSCA) antibody (scAbPSCA) as a specific 'address tag' for prostate cancer targeted imaging and therapy []. Prostate stem cell antigen is a prostate-specific glycosyl phosphatidylinositol-anchored glycoprotein that is marginally expressed in normal prostate and overexpressed in prostate cancer tissues []. As shown in Figure A, the scAbPSCA was prepared by cleaving intact AbPSCA with mercaptoethylamine (MEA), followed by linking to maleimide-PEG-carboxyl (MAL-PEG-COOH) and covalent conjugation to multifunctional polymeric vesicles that had been formed by the entrapping of superparamagnetic iron oxide (SPIO) nanoparticles and docetaxel (Dtxl) by amine-terminated poly(lactic-co-glycolic) acid. The scAbPSCA-Dtxl/SPIO-NPs were 147 nm in size, as determined by dynamic light scattering (DLS), and the amounts of SPIOs and Dtxl in the polymer matrix were 23 wt% and 6.02 wt%, respectively. The high drug encapsulation efficiency was due to partitioning of Dtxl into the oleic acid and oleylamine shell of the SPIOs, which acted as a drug reservoir, thereby exhibiting a triphasic drug release pattern rather than the common two-phase kinetic release pattern, including burst effects of an initial release stage, as observed in vesicles without SPIOs. An cytotoxicity study demonstrated the antiproliferative effects of the multifunctional vesicles toward prostate cancer cells. As indicated in Figures B and C, PC3 cells incubated with scAbPSCA-Dtxl/SPIO-NPs produced distinct darkened regions in the T2-weighted MRI compared to the polymeric vesicles without scAbPSCA or Endorem® (a commercial contrast, Guerbet, France). This result demonstrated that the scAbPSCA-Dtxl/SPIO-NPs could be used as MRI contrast agents for prostate-targeted imaging and real-time monitoring of therapeutic effects.

Gold nanoparticle synthesis - Duration: 3:01.

Schematic illustration of the silica nanoporous particle-supported lipid bilayer, depicting the disparate types of therapeutic and diagnostic agents that can be loaded within the nanoporous silica core, as well as the ligands that can be displayed on the surface of the nanoparticle. Reproduced with permission from ref. [].

The synthesis of gold nanoparticles by a ..

Nanoporous silica offers a higher surface area and binding capacity for therapeutic and diagnostic agents compared to similarly sized liposomes, and, therefore, provides an attractive drug delivery system. Multicomponent cargos are easily loaded onto nanoporous silica cores, and the resultant nanocarriers can potentially be used for targeted multicomponent delivery. Ashley . developed porous silica nanoparticle-supported lipid bilayers (protocells, 100-150 nm in diameter) that synergistically combined the features of mesoporous silica particles and liposomes to address the multiple challenges of targeted delivery (Figure ) []. Protocells were modified with an SP94-targeted peptide that binds to human hepatocellular carcinoma and a histidine-rich fusogenic peptide that promotes endosomal escape of the protocells and cytosolic dispersion of the encapsulated cargos. The nanoporous support resulted in greater stability and enhanced lateral bilayer fluidity compared with both liposomes and non-porous particles, thereby promoting multivalent interactions between the protocell and the target cancer cell using a minimal number of targeting peptides via peptide recruitment to the cell surface. The high surface area and porosity of their nanoporous cores conveyed a one-thousand-fold higher capacity of the protocells for Dox than the similarly sized liposomes. The unique properties of protocells solve the problem of simultaneously achieving high targeting specificity, high cytotoxicity toward the target cell, and low collateral damage to non-cancerous cells. Cell viability tests indicated that Dox-loaded protocell treatment maintained greater than 90% normal hepatocyte viability while killing nearly 97% MDR1+ hepatocellular carcinoma (Hep3B). In contrast, Dox-loaded liposomes or protocells without fluidity on their surface were less efficient at killing Hep3B and caused considerable cytotoxicity to non-cancerous cells. The Dox-loaded protocells demonstrated good therapeutic ability compared to both free Dox and Dox-loaded liposomes.

the X-ray induced gold nanoparticle synthesis.

Nanomaterials offer new opportunities for cancer diagnosis and treatment. Multifunctional nanoparticles harboring various functions including targeting, imaging, therapy, and etc have been intensively studied aiming to overcome limitations associated with conventional cancer diagnosis and therapy. Of various nanoparticles, magnetic iron oxide nanoparticles with superparamagnetic property have shown potential as multifunctional nanoparticles for clinical translation because they have been used asmagnetic resonance imaging (MRI) constrast agents in clinic and their features could be easily tailored by including targeting moieties, fluorescence dyes, or therapeutic agents. This review summarizes targeting strategies for construction of multifunctional nanoparticles including magnetic nanoparticles-based theranostic systems, and the various surface engineering strategies of nanoparticles for applications.