http://www.jnanobiotechnology.com The latest research articles published by Journal of Nanobiotechnology 2010-02-24T00:00:00Z This is an RSS newsfeed from BioMed Central It is intended to be used with an RSS reader. For more information about RSS newsfeeds from BioMed Central, visit http://www.biomedcentral.com/info/about/rss/ Plasmid DNA encoding a luciferase reporter gene was complexed with each of six different hybrid nanoparticles (NPs) synthesized from mixtures of poly (D, L-lactide-co-glycolide acid) (PLGA 50:50) and the cationic lipids DOTAP (1, 2-Dioleoyl-3-Trimethyammonium-Propane) or DC-Chol {3β-[N-(N', N'-Dimethylaminoethane)-carbamyl] Cholesterol}. Particles were 100-400 nm in diameter and the resulting complexes had DNA adsorbed on the surface (out), encapsulated (in), or DNA adsorbed and encapsulated (both). A luciferase reporter assay was used to quantify DNA expression in 293 cells for the uptake of six different NP/DNA complexes. Optimal DNA delivery occurred for 105 cells over a range of 500 ng - 10 μg of NPs containing 20-30 μg DNA per 1 mg of NPs. Uptake of DNA from NP/DNA complexes was found to be 500-600 times as efficient as unbound DNA. Regression analysis was performed and lines were drawn for DNA uptake over a four week interval. NP/DNA complexes with adsorbed NPs (out) showed a large initial uptake followed by a steep slope of DNA decline and large angle of declination; lines from uptake of adsorbed and encapsulated NPs (both) also exhibited a large initial uptake but was followed by a gradual slope of DNA decline and small angle of declination, indicating longer times of luciferase expression in 293 cells. NPs with encapsulated DNA only (in), gave an intermediate activity. The latter two effects were best seen with DOTAP-NPs while the former was best seen with DC-Chol-NPs. These results provide optimal conditions for using different hybrid NP/DNA complexes in vitro and in the future, will be tested in vivo. http://www.jnanobiotechnology.com/content/8/1/6 Qiu Zhong Dakshina Murthy Devanga Chinta Sarala Pamujula Haifan Wang Xin Yao Tarun Mandal Ronald Luftig Journal of Nanobiotechnology 2010, 8:6 2010-02-24T00:00:00Z doi:10.1186/1477-3155-8-6 Journal of Nanobiotechnology 1477-3155 8 6 2010-02-24T00:00:00Z XML Molecular nanodiagnostics applied to cancer may provide rapid and sensitive detection of cancer related molecular alterations, which would enable early detection even when those alterations occur only in a small percentage of cells. The use of gold nanoparticles derivatized with thiol modified oligonucleotides (Au-nanoprobes) for the detection of specific nucleic acid targets has been gaining momentum as an alternative to more traditional methodologies. Here, we present an Au-nanoparticles based approach for the molecular recognition and quantification of the BCR-ABL fusion transcript (mRNA), which is responsible for chronic myeloid leukemia (CML), and to the best of our knowledge it is the first time quantification of a specific mRNA directly in cancer cells is reported. This inexpensive and very easy to perform Au-nanoprobe based method allows quantification of unamplified total human RNA and specific detection of the oncogene transcript. The sensitivity settled by the Au-nanoprobes allows differential gene expression from 10 ng.ul-1 of total RNA and takes less than 30 min to complete after total RNA extraction, minimizing RNA degradation. Also, at later stages, accumulation of malignant mutations may lead to resistance to chemotherapy and consequently poor outcome. Such a method, allowing for fast and direct detection and quantification of the chimeric BCR-ABL mRNA, could speed up diagnostics and, if appropriate, revision of therapy. This assay may constitute a promising tool in early diagnosis of CML and could easily be extended to further target genes with proven involvement in cancer development. http://www.jnanobiotechnology.com/content/8/1/5 Joao Conde Jesus de la Fuente Pedro Baptista Journal of Nanobiotechnology 2010, 8:5 2010-02-24T00:00:00Z doi:10.1186/1477-3155-8-5 Journal of Nanobiotechnology 1477-3155 8 5 2010-02-24T00:00:00Z PDF Background: Cosmeceuticals are cosmetic-pharmaceutical hybrids intended to enhance health and beauty of the skin. Nanocosmeceuticals use nano-sized system for the delivery of active ingredients to the targeted cells for better penetration. In this work, nanoemulsion from palm oil esters was developed as a delivery system to produce nanocosmeceuticals. The stability of the resulting formulation was tested using various methods. In addition, the effect of components i.e. Vitamin E and Pluronic F-68 on the formulation was also studied. Results: Both vitamin E and Pluronic F-68 were found to co-emulsify and co-stabilized the formulations. The best formulation was found to be the one having the composition of 10% Palm Oil Esters (POEs), 10% vitamin E, 24% Tween 80, 2.4% Pluronic F-68 and 53.6% deionized water. Those compositions are considered to be the best as a nanocosmeceutical product due to the small particle size (94.21 nm), low occurrence of Ostwald ripening and the stablity at different storing temperatures (5, 25 and 45 oC) for four weeks. Conclusions: Palm oil esters-in-water nanoemulsions loaded with vitamin E was successfully formulated and has the potential to be used as nanocosmeceuticals. http://www.jnanobiotechnology.com/content/8/1/4 Brian Sheng Xian Teo Mahiran Basri Mohd. Rezuwan Shah Zakaria Abu Bakar Salleh Raja Noor Zaliha Raja Abdul Rahman Mohd. Basyaruddin Abdul Rahman Journal of Nanobiotechnology 2010, 8:4 2010-02-23T00:00:00Z doi:10.1186/1477-3155-8-4 Journal of Nanobiotechnology 1477-3155 8 4 2010-02-23T00:00:00Z PDF Background: Nucleic acid based recognition of viral sequences can be used together with label-free biosensors to provide rapid, accurate confirmation of viral infection. To enhance detection sensitivity, gold nanoparticles can be employed with mass-sensitive acoustic biosensors (such as a quartz crystal microbalance) by either hybridising nanoparticle-oligonucleotide conjugates to complimentary surface-immobilised ssDNA probes on the sensor, or by using biotin-tagged target oligonucleotides bound to avidin-modified nanoparticles on the sensor. We have evaluated and refined these signal amplification assays for the detection from specific DNA sequences of Herpes Simplex Virus (HSV) type 1 and defined detection limits with a 16.5 MHz fundamental frequency thickness shear mode acoustic biosensor. Results: In the study the performance of semi-homogeneous and homogeneous assay formats (suited to rapid, single step tests) were evaluated utilising different diameter gold nanoparticles at varying DNA concentrations. Mathematical models were built to understand the effects of mass transport in the flow cell, the binding kinetics of targets to nanoparticles in solution, the packing geometries of targets on the nanoparticle, the packing of nanoparticles on the sensor surface and the effect of surface shear stiffness on the response of the acoustic sensor. This lead to the selection of optimised 15 nm nanoparticles that could be used with a 6 minute total assay time to achieve a limit of detection sensitivity of 5.2 × 10-12 M. Larger diameter nanoparticles gave poorer limits of detection than smaller particles. The limit of detection was three orders of magnitude lower than that observed using a hybridisation assay without nanoparticle signal amplification. Conclusions: An analytical model was developed to determine optimal nanoparticle diameter, concentration and probe density, which allowed efficient and rapid optimisation of assay parameters. Numerical analysis and subsequent associated experimental data suggests that the response of the mass sensitive biosensor system used in conjunction with captured particles was affected by i) the coupled mass of the particle, ii) the proximal contact area between the particle and the sensor surface and iii) the available capture area on the particle and binding dynamics to this capture area. The latter two effects had more impact on the detection limit of the system than any potential enhancement due to added mass from a larger nanoparticle. http://www.jnanobiotechnology.com/content/8/1/3 Yildiz Uludag Richard Hammond Matthew Cooper Journal of Nanobiotechnology 2010, 8:3 2010-02-14T00:00:00Z doi:10.1186/1477-3155-8-3 Journal of Nanobiotechnology 1477-3155 8 3 2010-02-14T00:00:00Z XML We have quantitatively analyzed the confocal spectra of colloidal quantum dots (QDs) in rat endothelial progenitor cells (EPCs) by using Leica TCS SP5 Confocal Microscopy System. Comparison of the confocal spectra of QDs located inside and outside EPCs revealed that the interaction between the QDs and EPCs effectively reduces the radius of the exciton confinement inside the QDs so that the excitonic energy increases and the QD fluorescence peak blueshifts. Furthermore, the EPC environment surrounding the QDs shields the QDs so that the excitation of the QDs inside the cells is relatively weak, whereas the QDs outside the cells can be highly excited. At high excitations, the occupation of the ground excitonic state in the QD outside the cells becomes saturated and high-energy states excited, resulting in a large relaxation energy and a broad fluorescence peak. This permits, in concept, to use QD biomarkers to monitor EPCs by characterizing QD fluorescence spectra. http://www.jnanobiotechnology.com/content/8/1/2 Matyas Molnar Ying Fu Peter Friberg Yun Chen Journal of Nanobiotechnology 2010, 8:2 2010-02-04T00:00:00Z doi:10.1186/1477-3155-8-2 Journal of Nanobiotechnology 1477-3155 8 2 2010-02-04T00:00:00Z XML Background: Silver nanoparticles have proven to exert antiviral activity against HIV-1 at non-cytotoxic concentrations, but the mechanism underlying their HIV-inhibitory activity has not been not fully elucidated. In this study, silver nanoparticles are evaluated to elucidate their mode of antiviral action against HIV-1 using a panel of different in vitro assays. Results: Our data suggest that silver nanoparticles exert anti-HIV activity at an early stage of viral replication, most likely as a virucidal agent or as an inhibitor of viral entry. Silver nanoparticles bind to gp120 in a manner that prevents CD4-dependent virion binding, fusion, and infectivity, acting as an effective virucidal agent against cell-free virus (laboratory strains, clinical isolates, T and M tropic strains, and resistant strains) and cell-associated virus. Besides, silver nanoparticles inhibit post-entry stages of the HIV-1 life cycle. Conclusions: These properties make them a broad-spectrum agent not prone to inducing resistance that could be used preventively against a wide variety of circulating HIV-1 strains. http://www.jnanobiotechnology.com/content/8/1/1 Humberto Lara Nilda Ayala-Nunez Liliana Ixtepan-Turrent Cristina Rodriguez-Padilla Journal of Nanobiotechnology 2010, 8:1 2010-01-20T00:00:00Z doi:10.1186/1477-3155-8-1 Journal of Nanobiotechnology 1477-3155 8 1 2010-01-20T00:00:00Z XML Laser Desorption Ionization Mass Spectrometry employs matrix which is co-crystallised with the analyte to achieve "soft ionization" that is the formation of ions without fragmentation. A variety of matrix-free and matrix-assisted LDI techniques and matrices have been reported to date. LDI has been achieved using ultra fine metal powders (UFMPs), desorption ionisation on silicon (DIOS), sol-gel assisted laser desorption/ionization (SGALDI), as well as with common MALDI matrices such as 2,5-dihydroxy benzoic acid (DHB), 3,5-dimethoxy-4-hydroxycinnamic acid (SA), α-cyano-4-hydroxycinnamic acid (CHCA) to name a few. A variety of matrix additives have been shown to improve matrix assisted desorption, including silicon nanowires (SiNW), carbon nanotubes (CNT), metal nanoparticles and nanodots. To our knowledge no evidence exists for the application of highly fluorescent CdSe/ZnS quantum dots to enhance MALDI desorption of biological samples. Here we report that although CdSe/ZnS quantum dots on their own can not substitute matrix in MALDI-MS, their presence has a moderately positive effect on MALDI desorption, improves the signal-to-noise ratio, peak quality and increases the number of detected peptides and the overall sequence coverage. http://www.jnanobiotechnology.com/content/7/1/10 Julian Bailes Loic Vidal Dimitri Ivanov Mikhail Soloviev Journal of Nanobiotechnology 2009, 7:10 2009-12-31T00:00:00Z doi:10.1186/1477-3155-7-10 Journal of Nanobiotechnology 1477-3155 7 10 2009-12-31T00:00:00Z XML We describe an intein based method to site-specifically conjugate Quantum Dots (QDs) to target proteins in vivo. This approach allows the covalent conjugation of any nanostructure and/or nanodevice to any protein and thus the targeting of such material to any intracellular compartment or signalling complex within the cells of the developing embryo. We genetically fused a pleckstrin-homology (PH) domain with the N-terminus half of a split intein (IN). The C-terminus half (IC) of the intein was conjugated to QDs in vitro. IC-QD's and RNA encoding PH-IN were microinjected into Xenopus embryos. In vivo intein-splicing resulted in fully functional QD-PH conjugates that could be monitored in real time within live embryos. Use of Near Infra Red (NIR)-emitting QDs allowed monitoring of QD-conjugates within the embryo at depths where EGFP is undetectable demonstrating the advantages of QD's for this type of experiment. In conclusion, we have developed a novel in vivo methodology for the site-specific conjugation of QD's and other artificial structures to target proteins in different intracellular compartments and signaling complexes. http://www.jnanobiotechnology.com/content/7/1/9 Anna Charalambous Maria Andreou Paris Skourides Journal of Nanobiotechnology 2009, 7:9 2009-12-10T00:00:00Z doi:10.1186/1477-3155-7-9 Journal of Nanobiotechnology 1477-3155 7 9 2009-12-10T00:00:00Z XML The aim of this study is to determine the effects of silver nanoparticles (Ag-NP) on vascular endothelial growth factor (VEGF)-and interleukin-1 beta (IL-1β)-induced vascular permeability, and to detect the underlying signaling mechanisms involved in endothelial cells. Porcine retinal endothelial cells (PRECs) were exposed to VEGF, IL-1β and Ag-NP at different combinations and endothelial cell permeability was analyzed by measuring the flux of RITC-dextran across the PRECs monolayer. We found that VEGF and IL-1β increase flux of dextran across a PRECs monolayer, and Ag-NP block solute flux induced by both VEGF and IL-1β. To explore the signalling pathway involved VEGF- and IL-1β-induced endothelial alteration, PRECs were treated with Src inhibitor PP2 prior to VEGF and IL-1β treatment, and the effects were recorded. Further, to clarify the possible involvement of the Src pathways in endothelial cell permeability, plasmid encoding dominant negative(DN) and constitutively active(CA) form of Src kinases were transfected into PRECs, 24 h prior to VEGF and IL-1β exposure and the effects were recorded. Overexpression of DN Src blocked both VEGF-and IL-1β-induced permeability, while overexpression of CA Src rescues the inhibitory action of Ag-NP in the presence or absence of VEGF and IL-1β. Further, an in vitro kinase assay was performed to identify the presence of the Src phosphorylation at Y419. We report that VEGF and IL-1β-stimulate endothelial permeability via Src dependent pathway by increasing the Src phosphorylation and Ag-NP block the VEGF-and IL-1β-induced Src phosphorylation at Y419. These results demonstrate that Ag-NP may inhibit the VEGF-and IL-1β-induced permeability through inactivation of Src kinase pathway and this pathway may represent a potential therapeutic target to inhibit the ocular diseases such as diabetic retinopathy. http://www.jnanobiotechnology.com/content/7/1/8 Sardarpasha Sheikpranbabu Kalimuthu Kalishwaralal Deepak Venkataraman Soo Hyun Eom Jongsun Park Sangiliyandi Gurunathan Journal of Nanobiotechnology 2009, 7:8 2009-10-30T00:00:00Z doi:10.1186/1477-3155-7-8 Journal of Nanobiotechnology 1477-3155 7 8 2009-10-30T00:00:00Z XML Scanning ion conductance microscopy (SICM) is a suitable tool for imaging surfaces of living cells in a contact-free manner. We have shown previously that SICM in backstep mode allows one to trace the outlines of entire cell somata and to detect changes in cellular shape and volume. Here we report that SICM can be employed to quantitatively observe cellular structures such as cell processes of living cells as well as cell somata of motile cells in the range of hours. http://www.jnanobiotechnology.com/content/7/1/7 Patrick Happel Irmgard Dietzel Journal of Nanobiotechnology 2009, 7:7 2009-10-27T00:00:00Z doi:10.1186/1477-3155-7-7 Journal of Nanobiotechnology 1477-3155 7 7 2009-10-27T00:00:00Z XML