Understanding Three Hydration-Dependent Transitions of Zwitterionic Carboxybetaine Hydrogel by Molecular Dynamics Simulations

In this work, molecular dynamics simulations were performed to study a carboxybetaine methacrylate (CBMA) hydrogel under various swelling states. The water content in this study ranged from 28% to 91% of the total weight of the hydrogel. Three transitions of the CBMA hydrogel were observed as the water content increased. The first transition occurs when the water content increases from 33% to 37%. The observed kink in the self-diffusion coefficient of water indicates that the hydration of the polymer network of the hydrogel is saturated; the further added water is in a less confined state. The second transition was found to be related to the physical cross-links of the polymer network. As the water content rises to above 62%, the lifetime of the physical cross-links decreases significantly. This abrupt change in the lifetime indicates that the transition represents the equilibrium swelling state of the hydrogel. Finally, the third transition was observed when the water content goes above 81%. The significant increases in the bond and angle energies of the polymer network indicate that the hydrogel reaches its upper limit swelling state at this transition. These results are comparable to previously published experimental studies of similar zwitterionic hydrogels

Formation and Stability of Substituted Pyromorphite: A Molecular Modeling Study

Soils contaminated with lead pose significant risk to human as well as terrestrial and aquatic ecosystems. Theoretical phase relationships and field observations suggest that the interaction of lead and phosphorus to form pyromorphites Pb5(PO4 )3 X (X= OH-, Br-, Cl-, or F-) is an important buffer mechanism controlling the migration and fixation of lead in the environment. We report a molecular modeling approach to investigate the formation and stability of the substituted pyromorphites, which involved evaluating the lattice energy of the minerals using ab initio quantum mechanics. The lattice energy values are used in a Born-Haber thermodynamic cycle to calculate the heat of formation of the minerals. The Gibbs free energy of the substituted pyromorphites is then calculated from the change in entropy and heat of formation. The systems investigated in this study include partial and total substitution of Pb2+ by Cd2+ and Zn2+ cations in chloropyromorphite (Pb5(PO4 )3Cl ). Results indicate the unstable nature of the substituted Pb pyromorphite. The stability of the substituted minerals is found in the order Pb-pyromorphite \u3e Cd-pyromorphite \u3e Zn-pyromorphite

Evaluating the Effect of Shear Stress on Graft-To Zwitterionic Polycarboxybetaine Coating Stability Using a Flow Cell

The effect of surface coatings on the performance of antifouling activity under flow can be influenced by the flow/coating interactions. This study evaluates the effect of surface coatings on antifouling activity under different flows for the analyses of coating stability. This was done by exposing DOPA-PCB-300/dopamine coated polydimethylsiloxane (PDMS) to physiological shear stresses using a recirculation system which consisted of dual chamber acrylic flow cells, tygon tubing, flow probe and meter, and perfusion pumps. The effect of shear stress induced by phosphate buffered saline flow on coating stability was characterized with differences in fibrinogen adsorption between control (coated PDMS not loaded with shear stress) and coated samples loaded with various shear stresses. Fibrinogen adsorption data showed that relative adsorption on coated PDMS that were not exposed to shear (5.73% ± 1.97%) was significantly lower than uncoated PDMS (100%, p \u3c 0.001). Furthermore, this fouling level, although lower, was not significantly different from coated PDMS membranes that were exposed to 1 dyn/cm2 (9.55% ± 0.09%, p = 0.23), 6 dyn/cm2 (15.92% ± 10.88%, p = 0.14), and 10 dyn/cm2 (21.62% ± 13.68%, p = 0.08). Our results show that DOPA-PCB-300/dopamine coatings are stable, with minimal erosion, under shear stresses tested. The techniques from this fundamental study may be used to determine the limits of stability of coatings in long-term experiments

Integrated bioinformatics analysis of IFITM1 as a prognostic biomarker and investigation of its immunological role in prostate adenocarcinoma

IntroductionProstate adenocarcinoma (PRAD) is a highly aggressive malignancy with high mortality and poor prognosis, and its potential mechanism remains unclear. Our study aimed to identify novel markers for the prognosis of PRAD using bioinformatics technology.MethodsThe GSE32571 dataset was downloaded from the GEO database, and analyzed via the limma R package to identify differentially expressed genes (DEGs) and differentially expressed immune score-related genes (DEISRGs). The immune-related genes (IRGs) were further obtained by overlapping DEISRGs and DEGs, and the core gene was identified via survival analysis. Furthermore, the expression level, prognostic value, and potential functions of the core gene were evaluated via multiple bioinformatics databases.ResultsA total of 301 IRGs were identified from the GSE32571 dataset, and IFITM1 was a down-regulated gene in several types of cancer, including PRAD. Besides, low expression of IFITM1 was associated with a poor prognosis in PRAD. GSEA indicated that the vital pathways of IFITM1-associated genes were mainly enriched in primary immunodeficiency, Th17 cell differentiation, Th1, and Th2 cell differentiation, natural killer cell-mediated cytotoxicity, myeloid dendritic cell activation, regulation of leukocyte activation, etc. Furthermore, IFITM1 was closely correlated with 22 types of tumor-infiltrating immune cells.DiscussionIFITM1 was a prognostic biomarker for PRAD patients, and it can be acted as a potential immune therapy target in PRAD

Label-free biomarker sensing in undiluted serum with suspended microchannel resonators

Improved methods are needed for routine, inexpensive monitoring of biomarkers that could facilitate earlier detection and characterization of cancer. Suspended microchannel resonators (SMRs) are highly sensitive, batch-fabricated microcantilevers with embedded microchannels that can directly quantify adsorbed mass via changes in resonant frequency. As in other label-free detection methods, biomolecular measurements in complex media such as serum are challenging due to high background signals from nonspecific binding. In this report, we demonstrate that carboxybetaine-derived polymers developed to adsorb directly onto SMR SiO[subscript 2] surfaces act as ultralow fouling and functionalizable surface coatings. Coupled with a reference microcantilever, this approach enables detection of activated leukocyte cell adhesion molecule (ALCAM), a model cancer biomarker, in undiluted serum with a limit of detection of 10 ng/mL.National Cancer Institute (U.S.) (contract R01CA119402)SAIC-Frederick (contract 28XS119)National Institutes of Health (U.S.). Biotechnology Training Fellowshi

Thermodynamics of Water Stabilization of Carboxybetaine Hydrogels from Molecular Dynamics Simulations

Hydrogels are highly flexible network polymers being developed as scaffolds for tissue engineering and joint replacement. Their mechanical properties depend largely on their water content. To determine the associated mechanical and thermodynamic properties, we apply the new two-phase thermodynamics method (2PT) to short, molecular dynamics (MD) trajectories of solvated carboxybetaine methacrylate (CBMA) hydrogels. The calculated optimum water content agrees well with recent experiments. We find that the thermodynamics is dominated by a competition between the enthalpy of tightly bound water molecules (which enhance the population of low-energy states of the hydrogel) and the entropy-driven formation of a quasi-liquid water phase in the void volume. These new insights into the role of water in stabilizing hydrophilic motifs is expected to guide design strategies aimed at creating hydrogels with improved performance

Achieving One‐Step Surface Coating of Highly Hydrophilic Poly(Carboxybetaine Methacrylate) Polymers on Hydrophobic and Hydrophilic Surfaces

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/108623/1/admi201400071.pd