TY  - JOUR
AU  - Obradović, Milena
AU  - Daković, Aleksandra
AU  - Smiljanić, Danijela
AU  - Ožegović, Milica
AU  - Marković, Marija A.
AU  - Rottinghaus, George E.
AU  - Krstić, Jugoslav
PY  - 2022
UR  - https://cer.ihtm.bg.ac.rs/handle/123456789/5349
AB  - Cationic surfactant - octadecyldimethylbenzyl ammonium chloride (ODMBA) was used for modification of the three natural raw materials - bentonite, kaolin and zeolite. Adsorption of ODMBA by minerals occurred via ion exchange of inorganic cations on minerals with surfactant. Organomodified minerals - organobentonite (OB), organokaolin (OK) and organozeolite (OZ) were studied as adsorbents for removal of two non-steroidal anti-inflammatory drugs - ibuprofen (IBU) and diclofenac sodium (DS) at pH 7. For all systems, the pseudo-second order model showed the best correlation to kinetic experimental data. In all cases, the positive values of Delta H degrees indicated that the adsorption of both IBU and DS by organomodified minerals was endothermic in nature. Equilibrium data were better described by the Freundlich isotherm model, pointing to adsorbent heterogeneous active sites for adsorption. Under applied experimental conditions, the highest adsorption of both drugs was achieved by OB, while much lower capacities were observed for OK and OZ. Nonlinear isotherms and physicochemical characterization of organomodified minerals after drugs adsorption suggested complex mechanism consisting of hydrophobic interactions between hydrophobic part of the drugs and surfactants alkyl chains, electrostatic interactions of anionic forms of IBU and DS with the cationic "head" of ODMBA, as well as anion exchange of counterion ions from ODMBA micelle and anionic forms of both drugs. Adsorption of both IBU and DS was strongly dependent on the amount of ODMBA ions in the minerals.
PB  - Elsevier
T2  - Microporous and Mesoporous Materials
T1  - Ibuprofen and diclofenac sodium adsorption onto functionalized minerals: Equilibrium, kinetic and thermodynamic studies
VL  - 335
SP  - 111795
DO  - 10.1016/j.micromeso.2022.111795
ER  - 

@article{
author = "Obradović, Milena and Daković, Aleksandra and Smiljanić, Danijela and Ožegović, Milica and Marković, Marija A. and Rottinghaus, George E. and Krstić, Jugoslav",
year = "2022",
abstract = "Cationic surfactant - octadecyldimethylbenzyl ammonium chloride (ODMBA) was used for modification of the three natural raw materials - bentonite, kaolin and zeolite. Adsorption of ODMBA by minerals occurred via ion exchange of inorganic cations on minerals with surfactant. Organomodified minerals - organobentonite (OB), organokaolin (OK) and organozeolite (OZ) were studied as adsorbents for removal of two non-steroidal anti-inflammatory drugs - ibuprofen (IBU) and diclofenac sodium (DS) at pH 7. For all systems, the pseudo-second order model showed the best correlation to kinetic experimental data. In all cases, the positive values of Delta H degrees indicated that the adsorption of both IBU and DS by organomodified minerals was endothermic in nature. Equilibrium data were better described by the Freundlich isotherm model, pointing to adsorbent heterogeneous active sites for adsorption. Under applied experimental conditions, the highest adsorption of both drugs was achieved by OB, while much lower capacities were observed for OK and OZ. Nonlinear isotherms and physicochemical characterization of organomodified minerals after drugs adsorption suggested complex mechanism consisting of hydrophobic interactions between hydrophobic part of the drugs and surfactants alkyl chains, electrostatic interactions of anionic forms of IBU and DS with the cationic "head" of ODMBA, as well as anion exchange of counterion ions from ODMBA micelle and anionic forms of both drugs. Adsorption of both IBU and DS was strongly dependent on the amount of ODMBA ions in the minerals.",
publisher = "Elsevier",
journal = "Microporous and Mesoporous Materials",
title = "Ibuprofen and diclofenac sodium adsorption onto functionalized minerals: Equilibrium, kinetic and thermodynamic studies",
volume = "335",
pages = "111795",
doi = "10.1016/j.micromeso.2022.111795"
}

Obradović, M., Daković, A., Smiljanić, D., Ožegović, M., Marković, M. A., Rottinghaus, G. E.,& Krstić, J.. (2022). Ibuprofen and diclofenac sodium adsorption onto functionalized minerals: Equilibrium, kinetic and thermodynamic studies. in Microporous and Mesoporous Materials
Elsevier., 335, 111795.
https://doi.org/10.1016/j.micromeso.2022.111795

Obradović M, Daković A, Smiljanić D, Ožegović M, Marković MA, Rottinghaus GE, Krstić J. Ibuprofen and diclofenac sodium adsorption onto functionalized minerals: Equilibrium, kinetic and thermodynamic studies. in Microporous and Mesoporous Materials. 2022;335:111795.
doi:10.1016/j.micromeso.2022.111795 .

Obradović, Milena, Daković, Aleksandra, Smiljanić, Danijela, Ožegović, Milica, Marković, Marija A., Rottinghaus, George E., Krstić, Jugoslav, "Ibuprofen and diclofenac sodium adsorption onto functionalized minerals: Equilibrium, kinetic and thermodynamic studies" in Microporous and Mesoporous Materials, 335 (2022):111795,
https://doi.org/10.1016/j.micromeso.2022.111795 . .

TY  - JOUR
AU  - Spasojević, Milica
AU  - Daković, Aleksandra S.
AU  - Rottinghaus, George Edwin
AU  - Obradović, Milena
AU  - Krajišnik, Danina R.
AU  - Marković, Marija A.
AU  - Krstić, Jugoslav
PY  - 2021
UR  - https://cer.ihtm.bg.ac.rs/handle/123456789/4492
AB  - A natural kaolin from Serbia was modified with different amounts of octadecyldimethylbenzyl ammonium (ODMBA) - (25, 50 and 90% of kaolin cation exchange capacity). Samples were denoted as OKR-25, OKR-50 and OKR-90. Several methods (FTIR spectroscopy, thermal analysis, zeta potential measurements, and N2 physisorption) were used for characterization of the organokaolinites. Adsorption of the common mycotoxins - ochratoxin A (OCHRA) and zearalenone (ZEN) by the organokaolinites was investigated at different levels of solid phase in suspension, different initial mycotoxin concentrations and different pH values. The natural kaolin was not effective in binding OCHRA or ZEN. Adsorption of both mycotoxins by organokaolinites increased with increasing amounts of solid phase as well as with increasing levels of surfactant on the kaolin surface. OCHRA and ZEN adsorption by all organokaolinites followed non-linear adsorption isotherms, at pH 3, 7 and 9. The maximum adsorption capacity for OCHRA adsorption was at pH 3 (4.8 mg/g for OKR-25, 26.7 mg/g for OKR-50 and 39.2 mg/g for OKR-90) that was calculated from the Langmuir model. Much lower OCHRA adsorption capacities were found at pH 7 and 9 (from 0.8 mg/g to 6.9 mg/g at pH 7 and from 1.1 mg/g to 4.6 mg/g at pH 9). The following adsorption capacities for ZEN were obtained from the Langmuir isotherms, at pH 3: 4.5 mg/g for OKR-25, 12.0 mg/g for OKR-50 and 13.5 mg/g for OKR-90. At pH 7, adsorption of ZEN was 5.7 mg/g for OKR-25, 15.3 mg/g for OKR-90 and 14. 4 mg/g for OKR-90. At pH 9, ZEN adsorption capacities were 2.4, 14.1 and 8.1 mg/g for OKR-25, OKR-50 and OKR-90, respectively. Thus, at the lowest amount of ODMBA at the kaolin surface, adsorption of ZEN was similar at pH 3 and 7, while a slightly lower value was obtained for its adsorption at pH 9. With increasing amounts of organic phase at the kaolin surface, the adsorption of ZEN was practically independent of pH. Adsorption of both mycotoxins was dependent on the amount of ODMBA ions at the kaolin surface as well as on their forms in solution.
PB  - Elsevier
T2  - Applied Clay Science
T1  - Influence of surface coverage of kaolin with surfactant ions on adsorption of ochratoxin A and zearalenone
VL  - 205
SP  - 106040
DO  - 10.1016/j.clay.2021.106040
ER  - 

@article{
author = "Spasojević, Milica and Daković, Aleksandra S. and Rottinghaus, George Edwin and Obradović, Milena and Krajišnik, Danina R. and Marković, Marija A. and Krstić, Jugoslav",
year = "2021",
abstract = "A natural kaolin from Serbia was modified with different amounts of octadecyldimethylbenzyl ammonium (ODMBA) - (25, 50 and 90% of kaolin cation exchange capacity). Samples were denoted as OKR-25, OKR-50 and OKR-90. Several methods (FTIR spectroscopy, thermal analysis, zeta potential measurements, and N2 physisorption) were used for characterization of the organokaolinites. Adsorption of the common mycotoxins - ochratoxin A (OCHRA) and zearalenone (ZEN) by the organokaolinites was investigated at different levels of solid phase in suspension, different initial mycotoxin concentrations and different pH values. The natural kaolin was not effective in binding OCHRA or ZEN. Adsorption of both mycotoxins by organokaolinites increased with increasing amounts of solid phase as well as with increasing levels of surfactant on the kaolin surface. OCHRA and ZEN adsorption by all organokaolinites followed non-linear adsorption isotherms, at pH 3, 7 and 9. The maximum adsorption capacity for OCHRA adsorption was at pH 3 (4.8 mg/g for OKR-25, 26.7 mg/g for OKR-50 and 39.2 mg/g for OKR-90) that was calculated from the Langmuir model. Much lower OCHRA adsorption capacities were found at pH 7 and 9 (from 0.8 mg/g to 6.9 mg/g at pH 7 and from 1.1 mg/g to 4.6 mg/g at pH 9). The following adsorption capacities for ZEN were obtained from the Langmuir isotherms, at pH 3: 4.5 mg/g for OKR-25, 12.0 mg/g for OKR-50 and 13.5 mg/g for OKR-90. At pH 7, adsorption of ZEN was 5.7 mg/g for OKR-25, 15.3 mg/g for OKR-90 and 14. 4 mg/g for OKR-90. At pH 9, ZEN adsorption capacities were 2.4, 14.1 and 8.1 mg/g for OKR-25, OKR-50 and OKR-90, respectively. Thus, at the lowest amount of ODMBA at the kaolin surface, adsorption of ZEN was similar at pH 3 and 7, while a slightly lower value was obtained for its adsorption at pH 9. With increasing amounts of organic phase at the kaolin surface, the adsorption of ZEN was practically independent of pH. Adsorption of both mycotoxins was dependent on the amount of ODMBA ions at the kaolin surface as well as on their forms in solution.",
publisher = "Elsevier",
journal = "Applied Clay Science",
title = "Influence of surface coverage of kaolin with surfactant ions on adsorption of ochratoxin A and zearalenone",
volume = "205",
pages = "106040",
doi = "10.1016/j.clay.2021.106040"
}

Spasojević, M., Daković, A. S., Rottinghaus, G. E., Obradović, M., Krajišnik, D. R., Marković, M. A.,& Krstić, J.. (2021). Influence of surface coverage of kaolin with surfactant ions on adsorption of ochratoxin A and zearalenone. in Applied Clay Science
Elsevier., 205, 106040.
https://doi.org/10.1016/j.clay.2021.106040

Spasojević M, Daković AS, Rottinghaus GE, Obradović M, Krajišnik DR, Marković MA, Krstić J. Influence of surface coverage of kaolin with surfactant ions on adsorption of ochratoxin A and zearalenone. in Applied Clay Science. 2021;205:106040.
doi:10.1016/j.clay.2021.106040 .

Spasojević, Milica, Daković, Aleksandra S., Rottinghaus, George Edwin, Obradović, Milena, Krajišnik, Danina R., Marković, Marija A., Krstić, Jugoslav, "Influence of surface coverage of kaolin with surfactant ions on adsorption of ochratoxin A and zearalenone" in Applied Clay Science, 205 (2021):106040,
https://doi.org/10.1016/j.clay.2021.106040 . .

TY  - JOUR
AU  - Jauković, Valentina
AU  - Krajišnik, Danina R.
AU  - Daković, Aleksandra S.
AU  - Damjanović, Ana B.
AU  - Krstić, Jugoslav
AU  - Stojanović, Jovica
AU  - Čalija, Bojan
PY  - 2021
UR  - https://cer.ihtm.bg.ac.rs/handle/123456789/4487
AB  - The functionality of halloysite (Hal) nanotubes as drug carriers can be improved by lumen enlargement and polymer modification. This study investigates the influence of selective acid etching on Hal functionalization with cationic biopolymer chitosan. Hal was subjected to lumen etching under mild conditions, loaded under vacuum with nonsteroidal antiinflammatory drug aceclofenac, and incubated in an acidic solution of chitosan. The functionality of pristine and etched Hal before and upon polymer functionalization was assessed by ζ-potential measurements, structural characterization (FT-IR, DSC and XRPD analysis), cell viability assay, drug loading and drug release studies. Acid etching increased specific surface area, pore volume and pore size of Hal, decreased ζ-potential and facilitated binding of the cationic polymer. XRPD and DSC analysis revealed crystalline structure of etched Hal. Successful chitosan binding and drug entrapment were further confirmed by FT-IR and DSC studies. XRPD showed surface polymer binding. DSC and FT-IR analyses confirmed the presence of the entrapped drug in its crystalline form. Drug loading was increased for ≈81% by selective lumen etching. Slight decrease of drug content occurred during chitosan functionalization due to aceclofenac diffusion in the polymer solution. The drug release was more sustained from etched Hal nanocomposites (up to ≈87% for 12 h) than from pristine Hal (up to ≈97% for 12 h) due to more intensive chitosan binding. High human fibroblast survival rates upon exposure to pristine and etched Hal before and after chitosan functionalization (>90% in the concentration of 1000 μg/mL) confirmed that both lumen etching under mild conditions and polymer functionalization had no significant effect on cytocompatibility. Based on these findings, selective lumen etching in combination with polycation modification appears to be a promising approach for improvement of Hal nanotubes functionality by increasing payload, polymer binding capacity, and sustained release properties with no significant effect on their cytocompatibility.
PB  - Elsevier
T2  - Materials Science and Engineering C
T1  - Influence of selective acid-etching on functionality of halloysite-chitosan nanocontainers for sustained drug release
VL  - 123
SP  - 112029
DO  - 10.1016/j.msec.2021.112029
ER  - 

@article{
author = "Jauković, Valentina and Krajišnik, Danina R. and Daković, Aleksandra S. and Damjanović, Ana B. and Krstić, Jugoslav and Stojanović, Jovica and Čalija, Bojan",
year = "2021",
abstract = "The functionality of halloysite (Hal) nanotubes as drug carriers can be improved by lumen enlargement and polymer modification. This study investigates the influence of selective acid etching on Hal functionalization with cationic biopolymer chitosan. Hal was subjected to lumen etching under mild conditions, loaded under vacuum with nonsteroidal antiinflammatory drug aceclofenac, and incubated in an acidic solution of chitosan. The functionality of pristine and etched Hal before and upon polymer functionalization was assessed by ζ-potential measurements, structural characterization (FT-IR, DSC and XRPD analysis), cell viability assay, drug loading and drug release studies. Acid etching increased specific surface area, pore volume and pore size of Hal, decreased ζ-potential and facilitated binding of the cationic polymer. XRPD and DSC analysis revealed crystalline structure of etched Hal. Successful chitosan binding and drug entrapment were further confirmed by FT-IR and DSC studies. XRPD showed surface polymer binding. DSC and FT-IR analyses confirmed the presence of the entrapped drug in its crystalline form. Drug loading was increased for ≈81% by selective lumen etching. Slight decrease of drug content occurred during chitosan functionalization due to aceclofenac diffusion in the polymer solution. The drug release was more sustained from etched Hal nanocomposites (up to ≈87% for 12 h) than from pristine Hal (up to ≈97% for 12 h) due to more intensive chitosan binding. High human fibroblast survival rates upon exposure to pristine and etched Hal before and after chitosan functionalization (>90% in the concentration of 1000 μg/mL) confirmed that both lumen etching under mild conditions and polymer functionalization had no significant effect on cytocompatibility. Based on these findings, selective lumen etching in combination with polycation modification appears to be a promising approach for improvement of Hal nanotubes functionality by increasing payload, polymer binding capacity, and sustained release properties with no significant effect on their cytocompatibility.",
publisher = "Elsevier",
journal = "Materials Science and Engineering C",
title = "Influence of selective acid-etching on functionality of halloysite-chitosan nanocontainers for sustained drug release",
volume = "123",
pages = "112029",
doi = "10.1016/j.msec.2021.112029"
}

Jauković, V., Krajišnik, D. R., Daković, A. S., Damjanović, A. B., Krstić, J., Stojanović, J.,& Čalija, B.. (2021). Influence of selective acid-etching on functionality of halloysite-chitosan nanocontainers for sustained drug release. in Materials Science and Engineering C
Elsevier., 123, 112029.
https://doi.org/10.1016/j.msec.2021.112029

Jauković V, Krajišnik DR, Daković AS, Damjanović AB, Krstić J, Stojanović J, Čalija B. Influence of selective acid-etching on functionality of halloysite-chitosan nanocontainers for sustained drug release. in Materials Science and Engineering C. 2021;123:112029.
doi:10.1016/j.msec.2021.112029 .

Jauković, Valentina, Krajišnik, Danina R., Daković, Aleksandra S., Damjanović, Ana B., Krstić, Jugoslav, Stojanović, Jovica, Čalija, Bojan, "Influence of selective acid-etching on functionality of halloysite-chitosan nanocontainers for sustained drug release" in Materials Science and Engineering C, 123 (2021):112029,
https://doi.org/10.1016/j.msec.2021.112029 . .