http://users.encs.concordia.ca/~mojtaba/elec6271/silver%20nanoparticles.pdf

Silver nanoparticles: green synthesis and their antimicrobial activities.

Epstein-Barr virus.

A one-step simple synthesis of silver colloid nanoparticles with controllable sizes is presented. In this synthesis, reduction of [Ag(NH3)2]+ complex cation by four saccharides was performed. Four saccharides were used:  two monosaccharides (glucose and galactose) and two disaccharides (maltose and lactose). The syntheses performed at various ammonia concentrations (0.005−0.20 mol L-1) and pH conditions (11.5−13.0) produced a wide range of particle sizes (25−450 nm) with narrow size distributions, especially at the lowest ammonia concentrations. The average size, size distribution, morphology, and structure of particles were determined by dynamic light scattering (DLS), transmission electron microscopy (TEM), and UV/Visible absorption spectrophotometry. The influence of the saccharide structure (monosacharides versus disaccharides) on the size of silver particles is briefly discussed. The reduction of [Ag(NH3)2]+ by maltose produced silver particles with a narrow size distribution with an average size of ...

Silver Colloid Nanoparticles: Synthesis, Characterization, and Their Antibacterial Activity

The physical and chemical properties of silver nanoparticles that are responsible for their antimicrobial activities have been studied with spherical silver nanoparticles (average diameter approximately 9 nm) synthesized by the borohydride reduction of Ag+ ions, in relation to their sensitivity to oxidation, activities towards silver-resistant bacteria, size-dependent activities, and dispersal in electrolytic solutions. Partially (surface) oxidized silver nanoparticles have antibacterial activities, but zero-valent nanoparticles do not. The levels of chemisorbed Ag+ that form on the particle's surface, as revealed by changes in the surface plasmon resonance absorption during oxidation and reduction, correlate well with the observed antibacterial activities. Silver nanoparticles, like Ag+ in the form of AgNO3 solution, are tolerated by the bacteria strains resistant to Ag+. The antibacterial activities of silver nanoparticles are related to their size, with the smaller particles having higher activities on the basis of equivalent silver mass content. The silver nanoparticles aggregate in media with a high electrolyte content, resulting in a loss of antibacterial activities. However, complexation with albumin can stabilize the silver nanoparticles against aggregation, leading to a retention of the antibacterial activities. Taken together, the results show that the antibacterial activities of silver nanoparticles are dependent on chemisorbed Ag+, which is readily formed owing to extreme sensitivity to oxygen. The antibacterial activities of silver nanoparticles are dependent on optimally displayed oxidized surfaces, which are present in well-dispersed suspensions.

Silver nanoparticles: partial oxidation and antibacterial activities.

Silver nanoparticles (nano-Ag) are potent and broad-spectrum antimicrobial agents. In this study, spherical nano-Ag (average diameter = 9.3 nm) particles were synthesized using a borohydride reduction method and the mode of their antibacterial action against E. coli was investigated by proteomic approaches (2-DE and MS identification), conducted in parallel to analyses involving solutions of Ag+ ions. The proteomic data revealed that a short exposure of E. coli cells to antibacterial concentrations of nano-Ag resulted in an accumulation of envelope protein precursors, indicative of the dissipation of proton motive force. Consistent with these proteomic findings, nano-Ag were shown to destabilize the outer membrane, collapse the plasma membrane potential and deplete the levels of intracellular ATP. The mode of action of nano-Ag was also found to be similar to that of Ag+ ions (e.g., Dibrov, P. et al, Antimicrob. Agents Chemother. 2002, 46, 2668−2670); however, the effective concentrations of nano-Ag and Ag...

Proteomic analysis of the mode of antibacterial action of silver nanoparticles

Silver nanoparticles fabricated in Hepes buffer exhibit cytoprotective activities toward HIV-1 infected cells.

Indoleamine 2, 3-dioxygenase (IDO) is a rate-limiting enzyme for the tryptophan catabolism In human and murine cells, IDO inhibits antigen-specific T cell proliferation in vitro and suppresses T cell responses to fetal alloantigens during murine pregnancy In mice, IDO expression is an inducible feature of specific subsets of dendritic cells (DCs), and is important for T cell regulatory properties However, the effect of IDO and tryptophan deprivation on DC functions remains unknown We report here that when tryptophan utilization was prevented by a pharmacological inhibitor of IDO, 1-methyl tryptophan (1MT), DC activation induced by pathogenic stimulus lipopolysaccharide (LPS) or inflammatory cytokine TNF-alpha was inhibited both phenotypically and functionally Such an effect was less remarkable when DC was stimulated by a physiological stimulus, CD40 ligand Tryptophan deprivation during DC activation also regulated the expression of CCR5 and CXCR4, as well as DC responsiveness to chemokines These results suggest that tryptophan usage in the microenvironment is essential for DC maturation, and may also play a role in the regulation of DC migratory behaviors

/pdf/indoleamine-2-3-dioxygenase-ido-is-essential-for-dendritic-1l3mdytioy.pdf

Indoleamine 2, 3-dioxygenase (IDO) is essential for dendritic cell activation and chemotactic responsiveness to chemokines.

Nasopharyngeal carcinoma (NPC) is a common neoplasm in Southeastern Asia, and cisplatin-containing regimens for combinational chemotherapy are widely used for treating locally recurrent or metastatic diseases. However, resistance to cisplatin is not infrequently seen and its associated side effects may be life-threatening. In this report, another metallo-pharmaceutical agent gold(III) porphyrin complex [Au(TPP)]Cl was investigated in comparison to cisplatin for its in vitro and in vivo anticancer effects. Through induction of the intrinsic apoptosis pathway, [Au(TPP)]Cl exhibited 100-fold higher potency than cisplatin in killing NPC cells, including cisplatin-sensitive and cisplatin-resistant variants, and also an variant harboring the Epstein-Barr virus. In addition, a safety concentration window was demonstrated, allowing [Au(TPP)]Cl to kill tumors with minimal cytotoxicity to noncancerous cells. More importantly, weekly intraperitoneal injection of 3 mg/kg [Au(TPP)]Cl was more effective than the same dose of cisplatin in inducing tumor apoptosis in vivo and remarkably inhibited tumor growth in animals without any noticeable side effect. [Au(TPP)]Cl therefore is a promising chemotherapeutic agent that deserves further development as a novel drug for the treatment of advanced NPC, in particular, for cases with cisplatin-resistance.

Gold(III) porphyrin complex is more potent than cisplatin in inhibiting growth of nasopharyngeal carcinoma in vitro and in vivo

A structurally characterized mixed-valent tetranuclear ruthenium-oxo oxalato cluster exhibits anti-viral activities toward R5- and X4-tropic HIV-1, and possesses cytoprotective activity toward HIV-1 infected cells.

A Mixed-Valent Ruthenium−Oxo Oxalato Cluster Na7[Ru4(μ3-O)4(C2O4)6] with Potent Anti-HIV Activities

Dendritic cells (DCs) are the most potent antigen-presenting cells, and are regarded as "natural adjuvants" for the induction of primary T or T-dependent immunity. DCs in the peripheral sites capture and process antigens. Encounter of exogenous or endogenous stimuli mature the function of DCs, and they thus acquire T-cell stimulatory capacity and distinct chemotactic behavior which enables them to migrate to lymphoid tissue. In the secondary lymphoid organs, they present antigens to T- and B-cells and stimulate their proliferation. Dendritic cells are also involved in tolerance induction, in particular, to self antigens. DCs also play a key role in the transmission of many pathogens, and therefore may become targets for designing new therapies. DCs have been manipulated in vitro and in vivo for cancer immunotherapy. In this article, we provide a concise overview of DC biology and its current and future role in clinical settings.

/pdf/dendritic-cells-sentinels-against-pathogens-2n3kxnqmqt.pdf

Chen-Lung Steve Lin

Papers

Silver nanoparticles fabricated in Hepes buffer exhibit cytoprotective activities toward HIV-1 infected cells.

Indoleamine 2, 3-dioxygenase (IDO) is essential for dendritic cell activation and chemotactic responsiveness to chemokines.

Gold(III) porphyrin complex is more potent than cisplatin in inhibiting growth of nasopharyngeal carcinoma in vitro and in vivo

A Mixed-Valent Ruthenium−Oxo Oxalato Cluster Na7[Ru4(μ3-O)4(C2O4)6] with Potent Anti-HIV Activities

Dendritic cells, sentinels against pathogens