The Experts below are selected from a list of 180 Experts worldwide ranked by ideXlab platform

Jem-kun Chen - One of the best experts on this subject based on the ideXlab platform.

  • pH-Sensitive Micelles Based on Star Copolymer Ad-(PCL-b-PDEAEMA-b-PPEGMA)4 for Controlled Drug Delivery
    Polymers, 2018
    Co-Authors: Huiyan Yang, Jianwei Guo, Rui Tong, Chufen Yang, Jem-kun Chen
    Abstract:

    Enhancing drug loading efficacy and stability of polymeric micelles remains a grand challenge. Here we develop adamantane-Based star copolymers adamantane-[poly(e-caprolactone)-b-poly(2-(diethylamino)ethyl methacrylate)-b-poly(poly(ethylene glycol) methyl ether methacrylate)]4 (Ad-(PCL-b-PDEAEMA-b-PPEGMA)4) and their self-assembled micelles for controlled drug delivery. Results show that the polymers have excellent stability in solution with low critical micelle concentration (CMC) (0.0025–0.0034 mg/mL) and the apparent Base Dissociation Constant (pKb) of the polymers is from 5.31 to 6.05. Dynamic light scattering analysis exhibits the great environmental response capability of the pH-sensitive micelles according to particle sizes and zeta potentials. With the synergy effect of the adamantane and hydrophobic block, the micelles display the high Doxorubicin (DOX) loading efficacy (up to 22.4%). The DOX release study shows that the micelles are capable of controlled release for drug. This work indicates the Ad-(PCL-b-PDEAEMA-b-PPEGMA)4 micelles may provide new guidelines for drug control and release system in overcoming cancer treatment.

  • pH-Sensitive Micelles Based on Star Copolymer Ad-(PCL-b-PDEAEMA-b-PPEGMA)4 for Controlled Drug Delivery
    MDPI AG, 2018
    Co-Authors: Huiyan Yang, Jianwei Guo, Rui Tong, Chufen Yang, Jem-kun Chen
    Abstract:

    Enhancing drug loading efficacy and stability of polymeric micelles remains a grand challenge. Here we develop adamantane-Based star copolymers adamantane-[poly(ε-caprolactone)-b-poly(2-(diethylamino)ethyl methacrylate)-b-poly(poly(ethylene glycol) methyl ether methacrylate)]4 (Ad-(PCL-b-PDEAEMA-b-PPEGMA)4) and their self-assembled micelles for controlled drug delivery. Results show that the polymers have excellent stability in solution with low critical micelle concentration (CMC) (0.0025–0.0034 mg/mL) and the apparent Base Dissociation Constant (pKb) of the polymers is from 5.31 to 6.05. Dynamic light scattering analysis exhibits the great environmental response capability of the pH-sensitive micelles according to particle sizes and zeta potentials. With the synergy effect of the adamantane and hydrophobic block, the micelles display the high Doxorubicin (DOX) loading efficacy (up to 22.4%). The DOX release study shows that the micelles are capable of controlled release for drug. This work indicates the Ad-(PCL-b-PDEAEMA-b-PPEGMA)4 micelles may provide new guidelines for drug control and release system in overcoming cancer treatment

Weiping Jia - One of the best experts on this subject based on the ideXlab platform.

  • Prediction of pKa Using Machine Learning Methods with Rooted Topological Torsion Fingerprints: Application to Aliphatic Amines
    Journal of chemical information and modeling, 2019
    Co-Authors: Shankara Anand, William A. Shirley, Peter Gedeck, Brian Kelley, Suzanne Skolnik, Stephane Rodde, Mai Nguyen, Mika Lindvall, Weiping Jia
    Abstract:

    The acid–Base Dissociation Constant, pKa, is a key parameter to define the ionization state of a compound and directly affects its biopharmaceutical profile. In this study, we developed a novel app...

  • Benefit of Retraining pKa Models Studied Using Internally Measured Data.
    Journal of chemical information and modeling, 2015
    Co-Authors: Peter Gedeck, Suzanne Skolnik, Stephane Rodde, Weiping Jia, Gavin Dollinger, Giuliano Berellini, Riccardo Vianello, Bernard Faller, Franco Lombardo
    Abstract:

    The ionization state of drugs influences many pharmaceutical properties such as their solubility, permeability, and biological activity. It is therefore important to understand the structure property relationship for the acid–Base Dissociation Constant pKa during the lead optimization process to make better-informed design decisions. Computational approaches, such as implemented in MoKa, can help with this; however, they often predict with too large error especially for proprietary compounds. In this contribution, we look at how retraining helps to greatly improve prediction error. Using a longitudinal study with data measured over 15 years in a drug discovery environment, we assess the impact of model training on prediction accuracy and look at model degradation over time. Using the MoKa software, we will demonstrate that regular retraining is required to address changes in chemical space leading to model degradation over six to nine months.

Huiyan Yang - One of the best experts on this subject based on the ideXlab platform.

  • pH-Sensitive Micelles Based on Star Copolymer Ad-(PCL-b-PDEAEMA-b-PPEGMA)4 for Controlled Drug Delivery
    Polymers, 2018
    Co-Authors: Huiyan Yang, Jianwei Guo, Rui Tong, Chufen Yang, Jem-kun Chen
    Abstract:

    Enhancing drug loading efficacy and stability of polymeric micelles remains a grand challenge. Here we develop adamantane-Based star copolymers adamantane-[poly(e-caprolactone)-b-poly(2-(diethylamino)ethyl methacrylate)-b-poly(poly(ethylene glycol) methyl ether methacrylate)]4 (Ad-(PCL-b-PDEAEMA-b-PPEGMA)4) and their self-assembled micelles for controlled drug delivery. Results show that the polymers have excellent stability in solution with low critical micelle concentration (CMC) (0.0025–0.0034 mg/mL) and the apparent Base Dissociation Constant (pKb) of the polymers is from 5.31 to 6.05. Dynamic light scattering analysis exhibits the great environmental response capability of the pH-sensitive micelles according to particle sizes and zeta potentials. With the synergy effect of the adamantane and hydrophobic block, the micelles display the high Doxorubicin (DOX) loading efficacy (up to 22.4%). The DOX release study shows that the micelles are capable of controlled release for drug. This work indicates the Ad-(PCL-b-PDEAEMA-b-PPEGMA)4 micelles may provide new guidelines for drug control and release system in overcoming cancer treatment.

  • pH-Sensitive Micelles Based on Star Copolymer Ad-(PCL-b-PDEAEMA-b-PPEGMA)4 for Controlled Drug Delivery
    MDPI AG, 2018
    Co-Authors: Huiyan Yang, Jianwei Guo, Rui Tong, Chufen Yang, Jem-kun Chen
    Abstract:

    Enhancing drug loading efficacy and stability of polymeric micelles remains a grand challenge. Here we develop adamantane-Based star copolymers adamantane-[poly(ε-caprolactone)-b-poly(2-(diethylamino)ethyl methacrylate)-b-poly(poly(ethylene glycol) methyl ether methacrylate)]4 (Ad-(PCL-b-PDEAEMA-b-PPEGMA)4) and their self-assembled micelles for controlled drug delivery. Results show that the polymers have excellent stability in solution with low critical micelle concentration (CMC) (0.0025–0.0034 mg/mL) and the apparent Base Dissociation Constant (pKb) of the polymers is from 5.31 to 6.05. Dynamic light scattering analysis exhibits the great environmental response capability of the pH-sensitive micelles according to particle sizes and zeta potentials. With the synergy effect of the adamantane and hydrophobic block, the micelles display the high Doxorubicin (DOX) loading efficacy (up to 22.4%). The DOX release study shows that the micelles are capable of controlled release for drug. This work indicates the Ad-(PCL-b-PDEAEMA-b-PPEGMA)4 micelles may provide new guidelines for drug control and release system in overcoming cancer treatment

Hans J Griesser - One of the best experts on this subject based on the ideXlab platform.

  • determination of the intrinsic acid Base Dissociation Constant and site density of ionizable surface groups by capillary rise measurements
    Langmuir, 1997
    Co-Authors: Ronald C Chatelier, Alastair Mcindoe Hodges, Calum J Drummond, Derek Y C Chan, Hans J Griesser
    Abstract:

    A theoretical description is presented for the equilibrium capillary height (heq) of a solution between parallel,flat,solidsurfaceswhichcontainionizablegroups. Theheqisrelatedtothechangeingravitational potential energy, the intrinsic wettability of the un-ionized surface, and the free energy of formation of theionizablesurfaceinaqueoussolution. Thetheoreticalapproachtakesintoaccountboththeelectrostatic free energy of charging the surface and the change in the free energy associated with the acid-Base reactions of the surface sites. It is shown that the dependence of heq on pH depends on the number of ionizable surface sites per unit area, the intrinsic acid-Base Dissociation Constant (Ka i ) of the surface sites, andthebackgroundelectrolyte. Thenegativefreeenergychangewhichaccompaniestheacid-Basereactions dominates over the positive electrostatic free energy of charging the surface. Consequently, the overall free energy of ionization is negative, and an ionized surface is more wettable than an un-ionized surface. The theoretical description is applied to experimental values ofheqas a function of pH, measured between two heptylamine plasma polymer surfaces in the presence of 1 mM NaCl. The theoretical fit to the data indicates that the plasma polymer surface contains ca. 1017 amines/m2 and the pKa i of the amine groups is ca. 5. The surface site density is in reasonable accord with values obtained by both derivatization techniquesandcontactanglemeasurements. ThepKa i isconsistentwithaloweffectivedielectricConstant for the polymer-water interface.

  • Theory of Contact Angles and the Free Energy of Formation of Ionizable Surfaces: Application to Heptylamine Radio-Frequency Plasma-Deposited Films
    Langmuir, 1995
    Co-Authors: Ronald C Chatelier, Calum J Drummond, Derek Y C Chan, Zoran R. Vasic, Thomas R. Gengenbach, Hans J Griesser
    Abstract:

    A theoretical description is presented for the macroscopic contact angle (θ) of a solid/vapor/aqueous solution interface when the solid surface is ionizable and relatively hydrophobic. The contact angle is related to the free energy of formation of the ionizable surface in aqueous solution. Therefore, the theoretical approach takes into account the electrostatic free energy of charging the surface and the change in the free energy associated with the acid-Base reactions of the surface sites. It is shown that the dependence of θ on pH depends on the number ofionizable surface sites per unit area, the intrinsic acid-Base Dissociation Constant (K a i ) of the surface sites, and the background electrolyte. The negative free energy change which accompanies the acid-Base reactions dominates over the positive electrostatic free energy of charging the surface ; therefore, the overall free energy of ionization is negative, and the ionized surfaces are more wettable than the uncharged surfaces. The theoretical description is applied to experimental values of θ as a function of pH, measured on heptylamine plasma polymer surfaces in the presence of either 1 or 10 mM NaCl. The theoretical fit to the advancing and sessile contact angles indicates that the plasma polymer surface contains ca. 4±1x10 17 amines/m 2 and the pK a i of the amine groups is ca. 6. The surface site density is in accord with values obtained by derivatization techniques, and the pK a i is consistent with a low effective dielectric Constant for the polymer-water interfacial microenvironment.

Jianwei Guo - One of the best experts on this subject based on the ideXlab platform.

  • pH-Sensitive Micelles Based on Star Copolymer Ad-(PCL-b-PDEAEMA-b-PPEGMA)4 for Controlled Drug Delivery
    Polymers, 2018
    Co-Authors: Huiyan Yang, Jianwei Guo, Rui Tong, Chufen Yang, Jem-kun Chen
    Abstract:

    Enhancing drug loading efficacy and stability of polymeric micelles remains a grand challenge. Here we develop adamantane-Based star copolymers adamantane-[poly(e-caprolactone)-b-poly(2-(diethylamino)ethyl methacrylate)-b-poly(poly(ethylene glycol) methyl ether methacrylate)]4 (Ad-(PCL-b-PDEAEMA-b-PPEGMA)4) and their self-assembled micelles for controlled drug delivery. Results show that the polymers have excellent stability in solution with low critical micelle concentration (CMC) (0.0025–0.0034 mg/mL) and the apparent Base Dissociation Constant (pKb) of the polymers is from 5.31 to 6.05. Dynamic light scattering analysis exhibits the great environmental response capability of the pH-sensitive micelles according to particle sizes and zeta potentials. With the synergy effect of the adamantane and hydrophobic block, the micelles display the high Doxorubicin (DOX) loading efficacy (up to 22.4%). The DOX release study shows that the micelles are capable of controlled release for drug. This work indicates the Ad-(PCL-b-PDEAEMA-b-PPEGMA)4 micelles may provide new guidelines for drug control and release system in overcoming cancer treatment.

  • pH-Sensitive Micelles Based on Star Copolymer Ad-(PCL-b-PDEAEMA-b-PPEGMA)4 for Controlled Drug Delivery
    MDPI AG, 2018
    Co-Authors: Huiyan Yang, Jianwei Guo, Rui Tong, Chufen Yang, Jem-kun Chen
    Abstract:

    Enhancing drug loading efficacy and stability of polymeric micelles remains a grand challenge. Here we develop adamantane-Based star copolymers adamantane-[poly(ε-caprolactone)-b-poly(2-(diethylamino)ethyl methacrylate)-b-poly(poly(ethylene glycol) methyl ether methacrylate)]4 (Ad-(PCL-b-PDEAEMA-b-PPEGMA)4) and their self-assembled micelles for controlled drug delivery. Results show that the polymers have excellent stability in solution with low critical micelle concentration (CMC) (0.0025–0.0034 mg/mL) and the apparent Base Dissociation Constant (pKb) of the polymers is from 5.31 to 6.05. Dynamic light scattering analysis exhibits the great environmental response capability of the pH-sensitive micelles according to particle sizes and zeta potentials. With the synergy effect of the adamantane and hydrophobic block, the micelles display the high Doxorubicin (DOX) loading efficacy (up to 22.4%). The DOX release study shows that the micelles are capable of controlled release for drug. This work indicates the Ad-(PCL-b-PDEAEMA-b-PPEGMA)4 micelles may provide new guidelines for drug control and release system in overcoming cancer treatment