Advanced Colloids Experiment (Temperature Controlled) ACE-T5

The attached will be presented at the JSC Science Symposium as a preview of the ACE-T5 flight experiment. The Principal Investigator (PI) for this experiment is Professor Ali Mohraz at the University of California - Irvine.Bijels (bicontinuous interfacially jammed emulsion gels) were discovered in 2007 at the University of Edinburgh. These materials feature a tubular, bicontinuous arrangement of two fluid phases separated by a monolayer of jammed colloidal particles at the interface.Because of their unique morphological characteristics, bijels hold significant promise as next-generation materials for energy and biotechnology applications. But in order to fully realize their potential, their physics and mechanical properties must be better understood. The mechanical properties and stability of bijels is mediated by an interplay between interfacial forces that impart elasticity to the system, and external stresses. Unfortunately, the interfacial forces are inherently coupled with density differences and cannot be studied systematically in the presence of gravity

Cloning, expression and library construction for HIV-1 Tat Protein

Background: Designing novel therapeutic agents has been a critical challenge for HIV disease.Materials and Methods: In current study a DNA sequence which was encoded the Tat protein was synthesized and inserted in pET 28 vector. Vector was cloned in BL21-DE3 E. coli and cultured in TB media. After protein expression, recombinant Tat protein was purified by NTA affinity chromatography. The Tat purified protein efficiency and confirmed by SDS-PAGE and Western blot, respectively. We were immunized the camel against HIV-1 Tat recombinant protein to made a camelid antibody library. Total RNA was extracted from camel lymphocytes and VHH fragments synthesized and amplified using RT-PCR and Nested- PCR methods by special primers.Results: The 350- 450 bp VHH gene fragment was produced by RT-PCR and Nested- PCR and extracted from agarose gel 1%. Then gel extraction was performed and pure fragments were inserted in HEN-4 vector by T4 DNA ligase.Conclusion: The library can be applied for biopanning and isolation of nanobody against HIV-1 Tat Protein. Nanobody small size may be a useful drug for treatment of HIV disease because give them the potency of the recognizing the cryptic epitopes of tat and neutralized the virus

Sexual Risk Behaviors and Condom Use Barriers in Iranian Men with Substance Use Disorders

Background: We aimed to investigate risky sexual behaviors (RSBs) and condom use barriers in Iranian men with substance use disorders (SUDs).Methods: Of the total 1800 outpatient drug free (ODF) and methadone maintenance treatment program (MMTP) active centers in Tehran, Iran, six were selected to participate in the current study. Data were collected (n = 300 men) using three questionnaires including a demographic questionnaire, the Risky Sexual Behavior Questionnaire (RSBQ), and the Condom Barriers Scale (CBS). The statistical software R, analysis of variance post hoc and multivariate analysis of variance (MANOVA) logistic regression tests were used in data analysis.Findings: The majority, (n = 194, 64.7%) reported at least one lifetime episode of RSBs. Compared to married participants (23.1%), 88.5% of single and 87.0% of divorced men had a history of RSB. Generally, the lowest and highest subscale scores of the CBS were related to sexual experience (2.60 ± 0.71) and access/availability structure (3.77 ± 0.54), respectively. The results of MANOVA analysis showed that there was a statistically significant difference between the CSB subscales based on the participants' education and marital status (P < 0.001). Only the partner barrier subscale had a significant negative relationship (P = 0.003) with RSB.Conclusion: Sexual dynamic of Iranian men with SUDs is different. Barriers to condom use seem to be socio-culturally determined. Culturally acceptable strategies need to be utilized in Iranian clinical settings reaching beyond simply condom accessibility for this at risk population

Prevalence and Correlates of Hepatitis C Infection among Male Injection Drug Users in Detention, Tehran, Iran

For the benefit of planning for the future care and treatment of people infected with hepatitis C virus (HCV) and to help guide prevention and control programs, data are needed on HCV seroprevalence and associated risk factors. We conducted a cross-sectional sero-behavioral survey of injection drug users (IDU) detained for mandatory rehabilitation during a police sweep of Tehran, Iran, in early 2006. During the study period, a consecutive sample comprising 454 of 499 (91.0%) men arrested and determined to be IDU by urine test and physical examination consented to a face-to-face interview and blood collection for HCV antibody testing. Overall, HCV prevalence was 80.0% (95% confidence interval (CI) 76.2–83.6). Factors independently associated with HCV infection included history of incarceration (adjusted OR 4.35, 95% CI 1.88–10.08), age of first injection ≤25 years (OR 2.72, 95% CI 1.09–6.82), and history of tattooing (OR 2.33, 95% CI 1.05–5.17). HCV prevalence in this population of IDU upon intake to jail was extremely high and possibly approaching saturation. Findings support that incarceration is contributing to the increased spread of HCV infection in Iran and calls for urgent increased availability of HCV treatment, long-term preparation for the care of complications of chronic infection, and rapid scale-up of programs for the primary prevention of parenterally transmitted infections among drug users

Effect of particle shape on the structure and rheology of colloidal suspensions and gels.

The role of particle geometry in mediating the structural and mechanical properties of colloidal suspensions and gels is investigated, using the techniques of laser light scattering, confocal laser scanning microscopy, and rheometry. The static structure of aggregated colloidal rods displays an unexpected dependence on the geometry of primary particles. Monte Carlo simulations of Brownian rod aggregation corroborate the experimental finding that the measured fractal dimension in the diffusion-limited cluster aggregation regime is an increasing function of the monomer aspect ratio. The implications of the observed behavior for colloidal gel dynamics are investigated by means of photon correlation spectroscopy. Increasing the rod aspect ratio decreases the minimum volume fraction for gelation. Further, the dynamic structure factor of rod clusters exhibits anomalous behavior, becoming highly non-exponential as the colloid volume fraction is increased. By means of light scattering in the flow-gradient plane of shear flow, the structural evolution of colloidal gels during the start-up of steady shear flow is investigated. Central forces between singly connected colloidal spheres in the gel backbone give rise to flexible structures that evolve through three distinct regimes: Orientation, rupture, and shear-densification. Universal scaling with the applied strain and retention of structural anisotropy upon flow cessation indicate the lack of structural relaxation mechanisms during cluster orientation. Rheological measurements demonstrate that the rupture point coincides with a maximum in shear stress. The volume fraction dependence of the critical strain for non-linear rupture agrees with the simple model of a gel network that ruptures after the cluster backbone is affinely extended to its full length. Fractal cluster gels whose primary constituents are anisometric form brittle structures whose orientation and rupture are not detectable by our apparatus. The finding reveals important effects of the primary particle geometry on the non-linear rheology of colloidal aggregates and gels. Suitable materials and image processing methods for confocal microscopic studies of anisometric colloids are developed. By means of three methods, the self-assembly of colloidal rod sediments is directly quantified. The ultimate sediment structure results from the interplay between thermodynamic and hydrodynamic variables such as particle rotational diffusivity, anisotropic excluded volume interactions, and sedimentation velocity.Ph.D.Applied SciencesChemical engineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/124510/2/3150045.pd

Effect of Porous Substrate Topographies on Cell Dynamics: A Computational Study.

Controlling cell-substrate interactions via the microstructural characteristics of biomaterials offers an advantageous path for modulating cell dynamics, mechanosensing, and migration, as well as for designing immune-modulating implants, all without the drawbacks of chemical-based triggers. Specifically, recent in vivo studies have suggested that a porous implants microscale curvature landscape can significantly impact cell behavior and ultimately the immune response. To investigate such cell-substrate interactions, we utilized a 3D computational model incorporating the minimum necessary physics of cell migration and cell-substrate interactions needed to replicate known in vitro behaviors. This model specifically incorporates the effect of membrane tension, which was found to be necessary to replicate in vitro cell behavior on curved surfaces. Our simulated substrates represent two classes of porous materials recently used in implant studies, which have markedly different microscale curvature distributions and pore geometries. We found distinct differences between the overall migration behaviors, shapes, and actin polymerization dynamics of cells interacting with the two substrates. These differences were correlated to the shape energy of the cells as they interacted with the porous substrates, in effect interpreting substrate topography as an energetic landscape interrogated by cells. Our results demonstrate that microscale curvature directly influences cell shape and migration and, therefore, is likely to influence cell behavior. This supports further investigation of the relationship between the surface topography of implanted materials and the characteristic immune response, a complete understanding of which would broadly advance principles of biomaterial design

Composite bijel-templated hydrogels for cell delivery.

Numerous processing techniques aim to impart interconnected, porous structures within regenerative medicine materials to support cell delivery and direct tissue growth. Many of these techniques lack predictable control of scaffold architecture, and rapid prototyping methods are often limited by time-consuming, layer-by-layer fabrication of micro-features. Bicontinuous interfacially jammed emulsion gels (bijels) offer a robust, self-assembly-based platform for synthesizing a new class of morphologically unique cell delivery biomaterials. Bijels form via kinetic arrest of temperature-driven spinodal decomposition in partially miscible binary liquid systems. These non-equilibrium soft materials are comprised of co-continuous, fully percolating, non-constricting liquid domains separated by a nanoparticle monolayer. Through the selective introduction of biocompatible precursors, hydrogel scaffolds displaying the morphological characteristics of the parent bijel can be formed. We report using bijel templating to generate structurally unique, fibrin-loaded polyethylene glycol hydrogel composites. Demonstration of composite bijel-templated hydrogels (CBiTHs) as a new cell delivery system was carried out in vitro using fluorescence-based tracking of cells delivered to previously acellular fibrin gels. Imaging analysis confirmed repeatable delivery of normal human dermal fibroblasts to acellular fibrin gels

Bijel-templated implantable biomaterials for enhancing tissue integration and vascularization.

Mitigation of the foreign body response (FBR) and successful tissue integration are essential to ensuring the longevity of implanted devices and biomaterials. The use of porous materials and coatings has been shown to have an impact, as the textured surfaces can mediate macrophage interactions with the implant and influence the FBR, and the pores can provide space for vascularization and tissue integration. In this study, we use a new class of implantable porous biomaterials templated from bicontinuous interfacially jammed emulsion gels (bijels), which offer a fully percolating, non-constricting porous network with a uniform pore diameter on the order of tens of micrometers, and surfaces with consistent curvature. We demonstrate that these unique morphological features, inherent to bijel-templated materials (BTMs), can enhance tissue integration and vascularization, and reduce the FBR. Cylindrical polyethylene glycol diacrylate (PEGDA) BTMs, along with PEGDA particle-templated materials (PTMs), and non-templated materials (NTMs), were implanted into the subcutaneous space of athymic nude mice. After 28 days, implants were retrieved and analyzed via histological techniques. Within BTMs, blood vessels of increased size and depth, changes in collagen deposition, and increased presence of pro-healing macrophages were observed compared to that of PTM and NTM implants. Bijel templating offers a new route to biomaterials that can improve the function and longevity of implantable devices. STATEMENT OF SIGNIFICANCE: All implanted biomaterials are subject to the foreign body response (FBR) which can have a detrimental effect on their efficacy. Altering the surface chemistry can decrease the FBR by limiting the amount of proteins adsorbed to the implant. This effect can be enhanced by including pores in the biomaterial to allow new tissue growth as the implant becomes integrated in the body. Here, we introduce a new class of self-assembled biomaterials comprising a fully penetrating, non-constricting pore phase with hyperbolic (saddle) surfaces for enhanced tissue integration. These unique morphological characteristics result in dense blood vessel formation and favorable tissue response properties demonstrated in a four-week implantation study

Composite Bijel-Templated Hydrogels for Cell Delivery

Numerous processing techniques aim to impart interconnected, porous structures within regenerative medicine materials to support cell delivery and direct tissue growth. Many of these techniques lack predictable control of scaffold architecture, and rapid prototyping methods are often limited by time-consuming, layer-by-layer fabrication of microfeatures. Bicontinuous interfacially jammed emulsion gels (bijels) offer a robust, self-assembly based platform for synthesizing a new class of morphologically unique cell delivery biomaterials. Bijels form via kinetic arrest of temperature-driven spinodal decomposition in partially miscible binary liquid systems. These nonequilibrium soft materials comprise cocontinuous, fully interpenetrating, nonconstricting liquid domains separated by a nanoparticle monolayer. Through the selective introduction of biocompatible precursors, hydrogel scaffolds displaying the morphological characteristics of the parent bijel can be formed. We report using bijel templating to generate structurally unique, fibrin-loaded polyethylene glycol hydrogel composites. Demonstration of composite bijel-templated hydrogels (CBiTHs) as a new cell delivery system was carried out in vitro using fluorescence-based tracking of cells delivered to previously acellular fibrin gels. Imaging analysis confirmed repeatable delivery of normal human dermal fibroblasts to acellular fibrin gels