Membrane Modification with Polydopamine to Improve Performances — A Mini Review

Syawaliah Muchtar, Mukramah Yusuf, Sri Mulyati, Yanna Syamsuddin, Umi Fathanah, Ryosuke Takagi

Abstract


This paper provides an overview of some studies and investigations regarding the utilization of polydopamine as an additive in membrane fabrication. Polydopamine is widely used due to its high hydrophilicity and adhesive properties. The addition of polydopamine in to the membrane system mostly attributed to the improvement of membrane performance in terms of permeation, antifouling, and antibiofouling.


Keywords


antibacterial; antifouling; bio-adhesive; hydrophilic; membrane fabrication; polydopamine

Full Text:

PDF

References


AHMAD, A. L., ABDULKARIM, A. A., OOI, B. S. & ISMAIL, S. 2013. Recent development in additives modifications of polyethersulfone membrane for flux enhancement. Chemical Engineering Journal, 223, 246-267.

ARENA, J. T., MANICKAM, S. S., REIMUND, K. K., FREEMAN, B. D. & MCCUTCHEON, J. R. 2014. Solute and water transport in forward osmosis using polydopamine modified thin film composite membranes. Desalination, 343, 8-16.

ARENA, J. T., MCCLOSKEY, B., FREEMAN, B. D. & MCCUTCHEON, J. R. 2011. Surface modification of thin film composite membrane support layers with polydopamine: Enabling use of reverse osmosis membranes in pressure retarded osmosis. Journal of Membrane Science, 375, 55-62.

BALL, V., FRARI, D. D., TONIAZZO, V. & RUCH, D. 2012. Kinetics of polydopamine film deposition as a function of pH and dopamine concentration: Insights in the polydopamine deposition mechanism. Journal of Colloid and Interface Science, 386, 366-372.

BERNSTEIN, R., BELFER, S. & FREGER, V. 2011. Bacterial Attachment to RO Membranes Surface-Modified by Concentration-Polarization-Enhanced Graft Polymerization. Environmental Science & Technology, 45, 5973-5980.

BRANCO, C. M., SHARMA, S., DE CAMARGO FORTE, M. M. & STEINBERGER-WILCKENS, R. 2016. New approaches towards novel composite and multilayer membranes for intermediate temperature-polymer electrolyte fuel cells and direct methanol fuel cells. Journal of Power Sources, 316, 139-159.

CAO, C., TAN, L., LIU, W., MA, J. & LI, L. 2014. Polydopamine coated electrospun poly(vinyldiene fluoride) nanofibrous membrane as separator for lithium-ion batteries. Journal of Power Sources, 248, 224-229.

CAO, X., TANG, M., LIU, F., NIE, Y. & ZHAO, C. 2010. Immobilization of silver nanoparticles onto sulfonated polyethersulfone membranes as antibacterial materials. Colloids and Surfaces B: Biointerfaces, 81, 555-562.

CHEN, Y. & HE, C. 2017. High salt permeation nanofiltration membranes based on NMG-assisted polydopamine coating for dye/salt fractionation. Desalination, 413, 29-39.

CHENG, C., LI, S., ZHAO, W., WEI, Q., NIE, S., SUN, S. & ZHAO, C. 2012. The hydrodynamic permeability and surface property of polyethersulfone ultrafiltration membranes with mussel-inspired polydopamine coatings. Journal of Membrane Science, 417-418, 228-236.

DEOWAN, S. A., GALIANO, F., HOINKIS, J., JOHNSON, D., ALTINKAYA, S. A., GABRIELE, B., HILAL, N., DRIOLI, E. & FIGOLI, A. 2016. Novel low-fouling membrane bioreactor (MBR) for industrial wastewater treatment. Journal of Membrane Science, 510, 524-532.

DING, X., YANG, C., LIM, T. P., HSU, L. Y., ENGLER, A. C., HEDRICK, J. L. & YANG, Y.-Y. 2012. Antibacterial and antifouling catheter coatings using surface grafted PEG-b-cationic polycarbonate diblock copolymers. Biomaterials, 33, 6593-6603.

DONG, Z., WANG, D., LIU, X., PEI, X., CHEN, L. & JIN, J. 2014. Bio-inspired surface-functionalization of graphene oxide for the adsorption of organic dyes and heavy metal ions with a superhigh capacity. Journal of Materials Chemistry A, 2, 5034-5040.

ELIMELECH, M. & PHILLIP, W. A. 2011. The Future of Seawater Desalination: Energy, Technology, and the Environment. 333, 712-717.

FAN, J., LUO, J., CHEN, X. & WAN, Y. 2016. Polydopamine meets porous membrane: A versatile platform for facile preparation of membrane adsorbers. Journal of Chromatography A, 1448, 121-126.

FANG, X., LI, J., LI, X., PAN, S., ZHANG, X., SUN, X., SHEN, J., HAN, W. & WANG, L. 2017. Internal pore decoration with polydopamine nanoparticle on polymeric ultrafiltration membrane for enhanced heavy metal removal. Chemical Engineering Journal, 314, 38-49.

FAURE, E., FALENTIN-DAUDRÉ, C., JÉRÔME, C., LYSKAWA, J., FOURNIER, D., WOISEL, P. & DETREMBLEUR, C. 2013. Catechols as versatile platforms in polymer chemistry. Progress in Polymer Science, 38, 236-270.

FENG, K., HOU, L., TANG, B. & WU, P. 2015. A self-protected self-cleaning ultrafiltration membrane by using polydopamine as a free-radical scavenger. Journal of Membrane Science, 490, 120-128.

GAO, W., LIANG, H., MA, J., HAN, M., CHEN, Z.-L., HAN, Z.-S. & LI, G.-B. 2011. Membrane fouling control in ultrafiltration technology for drinking water production: A review. Desalination, 272, 1-8.

HABIBI, S., NEMATOLLAHZADEH, A. & MOUSAVI, S. A. 2015. Nano-scale modification of polysulfone membrane matrix and the surface for the separation of chromium ions from water. Chemical Engineering Journal, 267, 306-316.

HERZBERG, M., SWEITY, A., BRAMI, M., KAUFMAN, Y., FREGER, V., ORON, G., BELFER, S. & KASHER, R. 2011. Surface Properties and Reduced Biofouling of Graft-Copolymers That Possess Oppositely Charged Groups. Biomacromolecules, 12, 1169-1177.

HILAL, N., KOCHKODAN, V., AL-KHATIB, L. & LEVADNA, T. 2004. Surface modified polymeric membranes to reduce (bio)fouling: a microbiological study using E. coli. Desalination, 167, 293-300.

JIANG, F., NIE, Y., YIN, L., FENG, Y., YU, Q. & ZHONG, C. 2016. Core-shell-structured nanofibrous membrane as advanced separator for lithium-ion batteries. Journal of Membrane Science, 510.

JIANG, J.-H., ZHU, L.-P., LI, X.-L., XU, Y.-Y. & ZHU, B.-K. 2010. Surface modification of PE porous membranes based on the strong adhesion of polydopamine and covalent immobilization of heparin. Journal of Membrane Science, 364, 194-202.

JIANG, J.-H., ZHU, L.-P., ZHANG, H.-T., ZHU, B.-K. & XU, Y.-Y. 2014. Improved hydrodynamic permeability and antifouling properties of poly(vinylidene fluoride) membranes using polydopamine nanoparticles as additives. Journal of Membrane Science, 457, 73-81.

JIANG, J., ZHU, L., ZHU, L., ZHU, B. & XU, Y. 2011. Surface Characteristics of a Self-Polymerized Dopamine Coating Deposited on Hydrophobic Polymer Films. Langmuir, 27, 14180-14187.

KARKHANECHI, H., RAZI, F., SAWADA, I., TAKAGI, R., OHMUKAI, Y. & MATSUYAMA, H. 2013. Improvement of antibiofouling performance of a reverse osmosis membrane through biocide release and adhesion resistance. Separation and Purification Technology, 105, 106-113.

KARKHANECHI, H., TAKAGI, R. & MATSUYAMA, H. 2014. Biofouling resistance of reverse osmosis membrane modified with polydopamine. Desalination, 336, 87-96.

KASEMSET, S., HE, Z., MILLER, D. J., FREEMAN, B. D. & SHARMA, M. M. 2016. Effect of polydopamine deposition conditions on polysulfone ultrafiltration membrane properties and threshold flux during oil/water emulsion filtration. Polymer, 97, 247-257.

KASEMSET, S., WANG, L., HE, Z., MILLER, D. J., KIRSCHNER, A., FREEMAN, B. D. & SHARMA, M. M. 2017. Influence of polydopamine deposition conditions on hydraulic permeability, sieving coefficients, pore size and pore size distribution for a polysulfone ultrafiltration membrane. Journal of Membrane Science, 522, 100-115.

KATSIKOGIANNI, M. & MISSIRLIS, Y. F. 2004. Concise review of mechanisms of bacterial adhesion to biomaterials and of techniques used in estimating bacteria-material interactions. Eur Cell Mater, 8, 37-57.

KIM, K.-Y., YANG, E., LEE, M.-Y., CHAE, K.-J., KIM, C.-M. & KIM, I. S. 2014. Polydopamine coating effects on ultrafiltration membrane to enhance power density and mitigate biofouling of ultrafiltration microbial fuel cells (UF-MFCs). Water Research, 54, 62-68.

LE, N. L. & NUNES, S. P. 2016. Materials and membrane technologies for water and energy sustainability. Sustainable Materials and Technologies, 7, 1-28.

LEE, H., DELLATORE, S. M., MILLER, W. M. & MESSERSMITH, P. B. 2007a. Mussel-inspired surface chemistry for multifunctional coatings. Science, 318, 426-30.

LEE, H., DELLATORE, S. M., MILLER, W. M. & MESSERSMITH, P. B. 2007b. Mussel-Inspired Surface Chemistry for Multifunctional Coatings. 318, 426-430.

LEE, H., RHO, J. & MESSERSMITH, P. B. 2009. Facile Conjugation of Biomolecules onto Surfaces via Mussel Adhesive Protein Inspired Coatings. 21, 431-434.

LEE, H., SCHERER, N. F. & MESSERSMITH, P. B. 2006. Single-molecule mechanics of mussel adhesion. Proc Natl Acad Sci U S A, 103, 12999-3003.

LI, F., MENG, J., YE, J., YANG, B., TIAN, Q. & DENG, C. 2014a. Surface modification of PES ultrafiltration membrane by polydopamine coating and poly(ethylene glycol) grafting: Morphology, stability, and anti-fouling. Desalination, 344, 422–430.

LI, Y., SU, Y., LI, J., ZHAO, X., ZHANG, R., FAN, X., ZHU, J., MA, Y., LIU, Y. & JIANG, Z. 2015. Preparation of thin film composite nanofiltration membrane with improved structural stability through the mediation of polydopamine. Journal of Membrane Science, 476, 10-19.

LI, Y., SU, Y., ZHAO, X., HE, X., ZHANG, R., ZHAO, J., FAN, X. & JIANG, Z. 2014b. Antifouling, High-Flux Nanofiltration Membranes Enabled by Dual Functional Polydopamine. ACS Applied Materials & Interfaces, 6, 5548-5557.

LIEBSCHER, J., MRÓWCZYŃSKI, R., SCHEIDT, H. A., FILIP, C., HĂDADE, N. D., TURCU, R., BENDE, A. & BECK, S. 2013. Structure of Polydopamine: A Never-Ending Story? Langmuir, 29, 10539-10548.

LIU, C. X., ZHANG, D. R., HE, Y., ZHAO, X. S. & BAI, R. 2010. Modification of membrane surface for anti-biofouling performance: Effect of anti-adhesion and anti-bacteria approaches. Journal of Membrane Science, 346, 121-130.

LIU, Y., AI, K. & LU, L. 2014. Polydopamine and Its Derivative Materials: Synthesis and Promising Applications in Energy, Environmental, and Biomedical Fields. Chemical Reviews, 114, 5057-5115.

LUO, C., LIU, W., LUO, B., TIAN, J., WEN, W., LIU, M. & ZHOU, C. 2017. Antibacterial activity and cytocompatibility of chitooligosaccharide-modified polyurethane membrane via polydopamine adhesive layer. Carbohydrate Polymers, 156, 235-243.

MCCLOSKEY, B., PARK, H. B., JU, H., ROWE, B., MILLER, D. & FREEMAN, B. 2012. A bioinspired fouling-resistant surface modification for water purification membranes. Journal of Membrane Science, s 413–414, 82–90.

MCCLOSKEY, B. D. Novel surface modifications and materials for fouling resistant water purification membranes. 2009.

MCCLOSKEY, B. D., PARK, H. B., JU, H., ROWE, B. W., MILLER, D. J., CHUN, B. J., KIN, K. & FREEMAN, B. D. 2010. Influence of polydopamine deposition conditions on pure water flux and foulant adhesion resistance of reverse osmosis, ultrafiltration, and microfiltration membranes. Polymer, 51, 3472-3485.

MUCHTAR, S., WAHAB, M. Y., FANG, L.-F., JEON, S., RAJABZADEH, S., TAKAGI, R., MULYATI, S., ARAHMAN, N., RIZA, M. & MATSUYAMA, H. 2019. Polydopamine-coated poly(vinylidene fluoride) membranes with high ultraviolet resistance and antifouling properties for a photocatalytic membrane reactor. 136, 47312.

MULYATI, S., APRILIA, S., MUCHTAR, S., SYAMSUDDIN, Y., ROSNELLY, C. M., BILAD, M. R., SAMSURI, S. & ISMAIL, N. M. 2022. Fabrication of Polyvinylidene Difluoride Membrane with Enhanced Pore and Filtration Properties by Using Tannic Acid as an Additive. 14, 186.

OH, K., KETPANG, K., KIM, H. & SHANMUGAM, S. 2016. Synthesis of sulfonated poly(arylene ether ketone) block copolymers for proton exchange membrane fuel cells. Journal of Membrane Science, 507.

OU, J., WANG, J., LIU, S., ZHOU, J., REN, S. & YANG, S. 2009.

Microtribological and electrochemical corrosion behaviors of polydopamine coating on APTS-SAM modified Si substrate. Applied Surface Science, 256, 894-899.

PAN, F., JIA, H., QIAO, S., JIANG, Z., WANG, J., WANG, B. & ZHONG, Y. 2009. Bioinspired fabrication of high performance composite membranes with ultrathin defect-free skin layer. Journal of Membrane Science, 341, 279-285.

PARK, N., KWON, B., KIM, I. & CHO, J. 2005. Biofouling potential of various NF membranes with respect to bacteria and their soluble microbial products (SMP): Characterizations, flux decline, and transport parameters. Journal of Membrane Science, 258, 43-54.

QIAN, X., OSTWAL, M., ASATEKIN, A., GEISE, G. M., SMITH, Z. P., PHILLIP, W. A., LIVELY, R. P. & MCCUTCHEON, J. R. 2022. A critical review and commentary on recent progress of additive manufacturing and its impact on membrane technology. Journal of Membrane Science, 645, 120041.

RAZI, F., SAWADA, I., OHMUKAI, Y., MARUYAMA, T. & MATSUYAMA, H. 2012a. The improvement of antibiofouling efficiency of polyethersulfone membrane by functionalization with zwitterionic monomers. Journal of Membrane Science, 401-402, 292-299.

RAZI, F., SAWADA, I., OHMUKAI, Y., MARUYAMA, T. & MATSUYAMA, H. 2012b. Surface Functionalization by Grafting (2-Dimethylamino)ethyl Methacrylate Methyl Chloride Quaternary Salt (DMAEMAq) onto Hollow Fiber Polyethersulfone (PES) Membranes for Improvement of Antibiofouling Properties. Solvent Extraction Research and Development, Japan, 19, 101-115.

RYOU, M.-H., LEE, Y. M., PARK, J.-K. & CHOI, J. W. 2011. Mussel-Inspired Polydopamine-Treated Polyethylene Separators for High-Power Li-Ion Batteries. 23, 3066-3070.

RYU, J., KU, S. H., LEE, H. & PARK, C. B. 2010. Mussel-Inspired Polydopamine Coating as a Universal Route to Hydroxyapatite Crystallization. 20, 2132-2139.

SHAO, B., LIU, L. F., YANG, F. L., SHAN, D. N. & YUAN, H. 2012. Membrane Modification Using Polydopamine and/or PDA Coated TiO2 Nano Particles for Wastewater Treatment. Procedia Engineering, 44, 1431-1432.

SHEVATE, R., KUMAR, M., KARUNAKARAN, M., HEDHILI, M. N. & PEINEMANN, K.-V. 2017. Polydopamine/Cysteine surface modified isoporous membranes with self-cleaning properties. Journal of Membrane Science, 529, 185-194.

SHI, C., DAI, J., HUANG, S., LI, C., SHEN, X., ZHANG, P., WU, D., SUN, D. & ZHAO, J. 2016. A simple method to prepare a polydopamine modified core-shell structure composite separator for application in high-safety lithium-ion batteries. Journal of Membrane Science, 518.

SHIN, Y. M., LEE, Y. B. & SHIN, H. 2011. Time-dependent mussel-inspired functionalization of poly(l-lactide-co-ɛ-caprolactone) substrates for tunable cell behaviors. Colloids and Surfaces B: Biointerfaces, 87, 79-87.

SIANIPAR, M., KIM, S. H., MIN, C., TIJING, L. D. & SHON, H. K. 2016. Potential and performance of a polydopamine-coated multiwalled carbon nanotube/polysulfone nanocomposite membrane for ultrafiltration application. Journal of Industrial and Engineering Chemistry, 34, 364-373.

SILEIKA, T. S., KIM, H.-D., MANIAK, P. & MESSERSMITH, P. B. 2011. Antibacterial Performance of Polydopamine-Modified Polymer Surfaces Containing Passive and Active Components. ACS Applied Materials & Interfaces, 3, 4602-4610.

VASELBEHAGH, M., KARKHANECHI, H., MULYATI, S., TAKAGI, R. & MATSUYAMA, H. 2014. Improved antifouling of anion-exchange membrane by polydopamine coating in electrodialysis process. Desalination, 332, 126-133.

WAHAB, M. Y., MUCHTAR, S., JEON, S., FANG, L.-F., RAJABZADEH, S., TAKAGI, R., ARAHMAN, N., MULYATI, S., RIZA, M. & MATSUYAMA, H. 2019. Synergistic effects of organic and inorganic additives in preparation of composite poly(vinylidene fluoride) antifouling ultrafiltration membranes. 136, 47737.

WANG, T., QIBLAWEY, H., SIVANIAH, E. & MOHAMMADIAN, A. 2016a. Novel methodology for facile fabrication of nanofiltration membranes based on nucleophilic nature of polydopamine. Journal of Membrane Science, 511, 65-75.

WANG, W., LI, R., TIAN, M., LIU, L., ZOU, H., ZHAO, X. & ZHANG, L. 2013. Surface Silverized Meta-Aramid Fibers Prepared by Bio-inspired Poly(dopamine) Functionalization. ACS Applied Materials & Interfaces, 5, 2062-2069.

WANG, X., YUAN, S., SHI, D., YANG, Y., JIANG, T., YAN, S., SHI, H., LUAN, S. & YIN, J. 2016b. Integrated antifouling and bactericidal polymer membranes through bioinspired polydopamine/poly(N-vinyl pyrrolidone) coating. Applied Surface Science, 375, 9-18.

WANG, Z., WANG, D., ZHANG, S., HU, L. & JIN, J. 2016c. Interfacial Design of Mixed Matrix Membranes for Improved Gas Separation Performance. 28, 3399-3405.

WEI, Q., ZHANG, F., LI, J., LI, B. & ZHAO, C. 2010. Oxidant-induced dopamine polymerization for multifunctional coatings. Polymer Chemistry, 1, 1430-1433.

WU, C., WANG, H., WEI, Z., LI, C. & LUO, Z. 2015. Polydopamine-mediated surface functionalization of electrospun nanofibrous membranes: Preparation, characterization and their adsorption properties towards heavy metal ions. Applied Surface Science, 346, 207-215.

WU, J., CONTRERAS, A. E. & LI, Q. 2014. Studying the impact of RO membrane surface functional groups on alginate fouling in seawater desalination. Journal of Membrane Science, 458, 120-127.

XI, Z.-Y., XU, Y.-Y., ZHU, L.-P., WANG, Y. & ZHU, B.-K. 2009. A facile method of surface modification for hydrophobic polymer membranes based on the adhesive behavior of poly(DOPA) and poly(dopamine). Journal of Membrane Science, 327, 244-253.

XU, K., FENG, B., ZHOU, C. & HUANG, A. 2016. Synthesis of highly stable graphene oxide membranes on polydopamine functionalized supports for seawater desalination. Chemical Engineering Science, 146, 159-165.

YANG, E., CHAE, K.-J., ALAYANDE, A. B., KIM, K.-Y. & KIM, I. S. 2016. Concurrent performance improvement and biofouling mitigation in osmotic microbial fuel cells using a silver nanoparticle-polydopamine coated forward osmosis membrane. Journal of Membrane Science, 513, 217-225.

YANG, H.-C., WU, Q.-Y., WAN, L.-S. & XU, Z.-K. 2013. Polydopamine gradients by oxygen diffusion controlled autoxidation. Chemical Communications, 49, 10522-10524.

YANG, L., LIU, X., ZHANG, X., CHEN, T., YE, Z. & RAHAMAN, M. S. 2022. High performance nanocomposite nanofiltration membranes with polydopamine-modified cellulose nanocrystals for efficient dye/salt separation. Desalination, 521, 115385.

YANG, L., PHUA, S. L., TEO, J. K. H., TOH, C. L., LAU, S. K., MA, J. & LU, X. 2011. A Biomimetic Approach to Enhancing Interfacial Interactions: Polydopamine-Coated Clay as Reinforcement for Epoxy Resin. ACS Applied Materials & Interfaces, 3, 3026-3032.

YE, Q., ZHOU, F. & LIU, W. 2011. Bioinspired catecholic chemistry for surface modification. Chemical Society Reviews, 40, 4244-4258.

YU, J., KAN, Y., RAPP, M., DANNER, E., WEI, W., DAS, S., MILLER, D., CHEN, Y., WAITE, J. & ISRAELACHVILI, J. 2013. Adaptive hydrophobic and hydrophilic interactions of mussel foot proteins with organic thin films. Proceedings of the National Academy of Sciences of the United States of America, 110, 15680-15685.

YU, M. & DEMING, T. J. 1998. Synthetic Polypeptide Mimics of Marine Adhesives. Macromolecules, 31, 4739-4745.

YU, W. & GRAHAM, N. J. D. 2015. Performance of an integrated granular media – Ultrafiltration membrane process for drinking water treatment. Journal of Membrane Science, 492, 164-172.

ZANGMEISTER, R. A., MORRIS, T. A. & TARLOV, M. J. 2013. Characterization of Polydopamine Thin Films Deposited at Short Times by Autoxidation of Dopamine. Langmuir, 29, 8619-8628.

ZHANG, R., SU, Y., ZHAO, X., LI, Y., ZHAO, J. & JIANG, Z. 2014. A novel positively charged composite nanofiltration membrane prepared by bio-inspired adhesion of polydopamine and surface grafting of poly(ethylene imine). Journal of Membrane Science, 470, 9-17.

ZHANG, W., YING, Y., MA, J., GUO, X., HUANG, H., LIU, D. & ZHONG, C. 2017. Mixed matrix membranes incorporated with polydopamine-coated metal-organic framework for dehydration of ethylene glycol by pervaporation. Journal of Membrane Science, 527, 8-17.

ZHOU, R., REN, P.-F., YANG, H.-C. & XU, Z.-K. 2014. Fabrication of antifouling membrane surface by poly(sulfobetaine methacrylate)/polydopamine co-deposition. Journal of Membrane Science, 466, 18-25.




DOI: https://doi.org/10.23955/rkl.v18i1.24918

Article Metrics

Abstract view : 0 times
PDF - 0 times

Refbacks

  • There are currently no refbacks.


Copyright (c) 2023 Syawaliah Muchtar, Mukramah Yusuf, Sri Mulyati, Yanna Syamsuddin, Umi Fathanah, Ryosuke Takagi

Creative Commons License
This work is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.

JURNAL REKAYASA KIMIA & LINGKUNGAN

Jurusan Teknik Kimia Universitas Syiah Kuala, Jl. Tgk. Syech Abdur Rauf No.7, Kopelma Darussalam, Banda Aceh, INDONESIA

 

PRINCIPAL CONTACT

Nasrul Arahman, Prof. Dr. S.T., M.T.
Phone: +62813-6092-7917
E-mail: rkl@che.usk.ac.id, nasrular@usk.ac.id

 

SUPPORT CONTACT

Mirna Rahmah Lubis
E-mail: mirna@che.usk.ac.id
Wahyu Rinaldi, ST, M.Sc.
E-mail: wahyu.rinaldi@che.usk.ac.id

 

VISITORS