One pot synthesis of luminescent Mn doped ZnSe nanoparticles and its silica based water dispersible formulation for targeted delivery of doxorubicin

The manganese doped zinc selenide nanoparticles (ZnSe:Mn NPs) were synthesized by thermolysis method using oleic acid and oleylamine as a capping agent, 1-octadecene as solvent. Coating of mesoporous silica was done on ZnSe:Mn (ZnSe:Mn@mSilica) which was further functionalized with amine functional groups by treating with (3-aminopropyl)trimethoxysilane. Further pegylation was done to achieve water dispersibility by conjugating carboxyl groups of poly(ethylene glycol) diacid with the amine groups. These pegylated NPs were subsequently treated with ethylenediamine followed by acrylic acid. Conjugation of tris-(hydroxymethyl-aminomethan) was performed by Michael-type addition reaction to afford ZnSe:Mn@mSilica-PEG-Tris-OH. These TRIS functionalized NPs exhibited broad emission ranging from 590-620 nm that is an indicative for their suitability in diagnosis and monitoring progress of cancer treatment. To explore the usefulness of increased surface area because of mesoporosity, doxorubicin was loaded on ZnSe:Mn@mSilica-PEG-Tris-OH NPs through silyl ether linkage and evaluated for cytotoxicity against WEHI-164 mouse fibrosarcoma and RAJI human hematopoietic origin cancer cell lines. A decrease in 12 % of cell viability of WEHI-164 cells while 30% decrease in RAJI cell lines (IC50 ≈ 45 nM) were observed.  This shows that our formulation has more cytotoxic in RAJI cancer cell lines than that of WEHI-164 cancer cells. These results revealed that the formulation has potential for the application in drug delivery and diagnosis in chemotherapeutics

One pot synthesis of luminescent Mn doped ZnSe nanoparticles and their silica based water dispersible formulation for targeted delivery of doxorubicin

348-355The manganese doped zinc selenide nanoparticles (ZnSe:Mn NPs) have been synthesized by thermolysis method using oleic acid and oleylamine as capping agents, and 1-octadecene as solvent. Coating of mesoporous silica is done on ZnSe:Mn (ZnSe:Mn@mSilica) which is further functionalized with amine functional groups by treating with (3-aminopropyl)trimethoxysilane. Further pegylation is done to achieve water dispersibility by conjugating carboxyl groups of poly(ethylene glycol) diacid with the amine groups. These pegylated NPs are subsequently treated with ethylenediamine followed by acrylic acid. Conjugation of tris-(hydroxymethyl-aminomethane) is performed by Michael-type addition reaction to afford ZnSe:Mn@mSilica-PEG-Tris-OH. These tris functionalized NPs have exhibited broad emission ranging from 590-620 nm that is an indicative for their suitability in diagnosis and monitoring progress of cancer treatment. To explore the usefulness of increased surface area because of mesoporosity, doxorubicin is loaded on ZnSe:Mn@mSilica-PEG-Tris-OH NPs through silyl ether linkage and evaluated for cytotoxicity against WEHI-164 mouse fibrosarcoma and RAJI human hematopoietic origin cancer cell lines. A decrease in 12% of cell viability of WEHI-164 cells while 30% decrease in RAJI cell lines (IC50 ≈ 45 nM) are observed. This shows that our formulation has more cytotoxic in RAJI cancer cell lines than that of WEHI-164 cancer cells. These results reveal that the formulation has potential for the application in drug delivery and diagnosis in chemotherapeutics

Serum immunoglobulin G, M and A response to Cryptosporidium parvum in Cryptosporidium-HIV co-infected patients

<p>Abstract</p> <p>Background</p> <p><it>Cryptosporidium parvum</it>, the protozoan parasite, causes a significant enteric disease in immunocompromised hosts such as HIV patients. The present study was aimed to compare serum IgG, IgM and IgA responses to crude soluble antigen of <it>C. parvum </it>in HIV seropositive and seronegative patients co-infected with <it>Cryptosporidium </it>and to correlate the responses with symptomatology.</p> <p>Methods</p> <p><it>Cryptosporidium parvum </it>specific serum antibody (IgG, IgM and IgA) responses were assessed by ELISA in 11 HIV seropositive <it>Cryptosporidium </it>positive (Group I), 20 HIV seropositive <it>Cryptosporidium </it>negative (Group II), 10 HIV seronegative <it>Cryptosporidium </it>positive (Group III), 20 HIV seronegative <it>Cryptosporidium </it>negative healthy individuals (Group IV) and 25 patients with other parasitic diseases (Group V).</p> <p>Results</p> <p>A positive IgG and IgA antibody response was observed in significantly higher number of <it>Cryptosporidium </it>infected individuals (Gp I and III) compared to <it>Cryptosporidium </it>un-infected individuals (Gp II, IV and V) irrespective of HIV/immune status. Sensitivity of IgG ELISA in our study was found to be higher as compared to IgM and IgA ELISA. The number of patients with positive IgG, IgM and IgA response was not significantly different in HIV seropositive <it>Cryptosporidium </it>positive patients with diarrhoea when compared to patients without diarrhoea and in patients with CD4 counts <200 when compared to patients with CD4 counts >200 cells/μl.</p> <p>Conclusion</p> <p>The study showed specific serum IgG and IgA production in patients infected with <it>Cryptosporidium</it>, both HIV seropositive and seronegative as compared to uninfected subjects suggesting induction of <it>Cryptosporidium </it>specific humoral immune response in infected subjects. However, there was no difference in number of patients with positive response in HIV seropositive or seronegative groups indicating that HIV status may not be playing significant role in modulation of <it>Cryptosporidium </it>specific antibody responses. The number of patients with positive IgG, IgM and IgA response was not significantly different in patients with or without history of diarrhoea thereby indicating that <it>Cryptosporidium </it>specific antibody responses may not be necessarily associated with protection from symptomatology.</p

Differential Expression of the Two kdp Operons in the Nitrogen-Fixing Cyanobacterium Anabaena sp. Strain L-31

In several types of bacteria, the Kdp ATPase (comprising of the KdpABC complex) is an inducible, high-affinity potassium transporter that scavenges K(+) from the environment. The cyanobacterium Anabaena sp. strain L-31 showed the presence of not one but two distinct kdp operons in its genome. The kdp1 consisted of kdpA1B1G1C1D genes, whereas the kdp2 contained the kdpA2B2G2C2 genes. Among the regulatory genes, the kdpD open reading frame of Anabaena sp. strain L-31 was truncated compared to the kdpD of other bacteria, whereas a kdpE-like gene was absent in the vicinity of the two kdp operons. In response to K(+) limitation (<0.05 mM external K(+)), only kdp2 (and not kdp1) expression could be detected as a 5.3-kb transcript on Northern blots, indicating that kdpA2B2G2C2 genes constitute a polycystronic operon. Unlike E. coli, addition of osmolytes like NaCl, or a change in pH of the medium did not enhance the kdp expression in Anabaena sp. strain L-31. Interestingly, the Anabaena sp. strain L-31 kdp2 operon was strongly induced in response to desiccation stress. The addition of K(+) to K(+)-starved cultures resulted in repression and degradation of kdp2 transcripts. Our results clearly show that kdp2 is the major kdp operon expressed in Anabaena sp. strain L-31 and may play an important role in adaptation to K(+) limitation and desiccation stress

Regulation of Superoxide Dismutase (sod) Genes by SarA in Staphylococcus aureus▿ †

The scavenging of reactive oxygen species (ROS) within cells is regulated by several interacting factors, including transcriptional regulators. Involvement of sarA family genes in the regulation of proteins involved in the scavenging of ROS is largely unknown. In this report, we show that under aerobic conditions, the levels of sodM and sodA transcription, in particular the sodM transcript, are markedly enhanced in the sarA mutant among the tested sarA family mutants. Increased levels of sod expression returned to near the parental level in a single-copy sarA complemented strain. Under microaerophilc conditions, transcription of both sodM and sodA was considerably enhanced in the sarA mutant compared to the wild-type strain. Various genotypic, phenotypic, and DNA binding studies confirmed the involvement of SarA in the regulation of sod transcripts in different strains of Staphylococcus aureus. The sodA mutant was sensitive to an oxidative stress-inducing agent, methyl viologen, but the sarA sodA double mutant was more resistant to the same stressor than the single sodA mutant. These results suggest that overexpression of SodM, which occurs in the sarA background, can rescue the methyl viologen-sensitive phenotype observed in the absence of the sodA gene. Analysis with various oxidative stress-inducing agents indicates that SarA may play a greater role in modulating oxidative stress resistance in S. aureus. This is the first report that demonstrates the direct involvement of a regulatory protein (SarA) in control of sod expression in S. aureus

Characterization of a response regulator protein that binds to Anabaena sp. strain L-31 kdp-promoter region

The potassium dependent adenosine triphosphatase (Kdp-ATPase), encoded by the kdp operon, is a potassium uptake system found in several prokaryotes. The cyanobacterium Anabaena sp. strain L-31 shows the presence of two kdp operons (kdp1 and kdp2) of which the kdp2 is predominantly induced in response to potassium limitation or desiccation stress. Two ORFs, encoding a sensor kinase and a response regulator, respectively, were identified upstream of the kdp2 operon in Anabaena sp. strain L-31. The response regulator protein, tagged with 6 additional C-terminal histidine residues, was over-expressed in Escherichia coli and purified by affinity chromatography. Employing the protein-specific antiserum, the response regulator protein was detected in Anabaena L-31 cytosolic fractions. The response regulator protein bound to the kdp2 promoter region with higher affinity than kdp1 promoter region. Addition of acetyl phosphate increased the ability of the protein to bind to kdp2 promoter region by several fold, suggesting a phosphorylation-dependent binding of response regulator to the promoter. These data implicate the response regulator protein in regulation of kdp2 expression in Anabaena sp. strain L-31

Cyanobacterial Mn-catalase ‘KatB’: Molecular link between salinity and oxidative stress resistance

Catalases are ubiquitous enzymes that detoxify H2O2 in virtually all organisms exposed to oxygen. The filamentous, nitrogen-fixing cyanobacterium, Anabaena PCC 7120, shows the presence of 2 genes (katA and katB) that encode Mn-catalases. We have recently shown that pre-treatment of Anabaena with NaCl causes substantial induction of the KatB protein, which consequently leads to increased oxidative stress resistance in that cyanobacterium. Interestingly, when compared to the wild-type, the katB mutant shows decreased growth and impaired photosynthetic activity in the presence of NaCl. Furthermore, the NaCl-treated katB mutant is extremely sensitive to H2O2. In this study, the ultrastructural changes occurring in the katB mutant and the wild-type Anabaena cells are analyzed to understand the cellular basis of the above-mentioned protective phenomena. Other data show that a wide variety of osmolytes induce katB expression in Anabaena, indicating that katB is a genuine osmo-inducible gene. These results have important biotechnological implications for the development of novel cyanobacterial biofertilzers and transgenic plants with improved resistance to salinity

ArsenazoIII functionalized gold nanoparticles: SPR based optical sensor for determination of uranyl ions (UO22+) in groundwater

Surface plasmon resonance (SPR) based spectrophotometric determination of UO22+ was carried out by arsenazoIII functionalized gold nanoparticles (AZ-AuNPs) based miniaturized detection assay in ground water samples. AZ-AuNPs were synthesized, characterized by transmission electron microscopy (TEM), x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), infrared spectroscopy (IR) and dynamic light scattering (DLS) techniques; AZ-AuNPs were of uniform size (∼10nm), dispersed, highly stable and negative charge surface. The addition of analyte (UO22+) into the detection assay led to UO22+-arsenazoIII complex formation and subsequent release of uncapped gold nanoparticules in solution. Agglomeration based SPR response of gold nanoparticles resulted in visual and spectrophotometric change in the detection assay. The UV-vis spectroscopic investigations showed changes in AZ-AuNPs characteristic absorption peak and an additional peak correspond to UO22+-arsenazoIII complex. Ratio of A650nm/A535nm was used to quantify the concentration of UO22+ in environmental samples. The method showed a linear response from 50−300 ppb (R2> 0.95) for UO22+ with the detection limit of 0.081 µM for ground water samples of total dissolve solids concentration of ∼1000 ppm

Cloning and characterization of the major groESL operon from a nitrogen-fixing cyanobacterium Anabaena sp. strain L-31

The major heat-shock-responsive operon groESL has been cloned from the cyanobacterial diazotroph Anabaena. The bicistronic operon harbors an upstream negative regulatory CIRCE element and is transcriptionally activated upon temperature upshift. The deduced amino acid sequence displays strong identity/similarity with other cyanobacterial GroES and GroEL proteins