Hypothesis: Sensitizing the nanocomposite hydrogel systems to multiple stimuli ensures increasing their efficiency from the viewpoint of the magnitude and rate of response of the system. Adding nanosilver to dual stimuli (pH and temperature) responsive chitosan/poly(vinyl alcohol)/nanoclay nanocomposite hydrogel system increases the sensitivity of the chosen system to the third stimulus, i.e. the electric field, and enhances the overall rate of response of the system. Methods: The reduction of a silver salt to silver nanoparticles was performed by a green synthesis method within the nanocomposite hydrogel system using chitosan as a reducing agent and polyvinyl alcohol as a stabilizer. Silver nanoparticle formation was investigated by UV-vis spectroscopy. SEM was used to study the distribution of silver nanoparticles in the nanocomposite system. The structural characterization of nanocomposite hydrogel was carried out by FTIR. Cyclic voltammetry was employed to evaluate the conductivity of the system. Findings: The peak observed at the wavelength of 410 nm confirmed the synthesis of nanosilver. The SEM micrograph showed the uniform distribution of nanosilver in the system. The results of the sensitivity of the responsive system to multiple stimuli indicated that the nanosilver increased the rate of response of the system in acidic and alkaline solutions. The maximum swelling rate of the system was at pH 2 and the temperature of 55°C, while the minimum rate was at pH 5 and the temperature of 20°C. The presence of nanosilver increased the rate of response of dual stimuli (pH and temperature) responsive system up to three times and its swelling rate to 1.5 times. By applying an electric field at pH 2, the time of response of system decreased from hours to minutes and its swelling ratio increased up to 1.7 times.
Endo T., Ikeda R., Yanagida Y., and Hatsuzawa T., Stimuli-Responsive Hydrogel–Silver Nanoparticles Composite for Development of Localized Surface Plasmon Resonance-Based Optical Biosensor, Analytica Chimica Acta, 611, 205-211, 2008.
Sood N., Bhardwaj A., and Mehta Sh., A. Mehta, Stimuli-Responsive Hydrogels in Drug Delivery and Tissue Engineering, Drug Deliv. J., 26, 1-23, 2014.
Stular D., Jerman I., Naglic I., Simoncic B., and Tomsic B., .Embedment of Silver into Temperature and pH Responsive Microgel for the Development of Smart Textiles with Simultaneous Moisture Management and Controlled Antimicrobial Activities, Carbohydr. Polym., 159, 161-170, 2017.
Cirillo G., Curcio M., Gianfranco Spizzirri U., Vittorio O., Tucci P., and Picci N., Carbon Nanotube Hybrid Hydrogels for Electrically Tunable Release of Curcumin, Eur. Polym. J., 90, 1-12, 2017.
Kim S., Kim H., Park S., Kim I., Lee S., Lee T., and Kim S., Behavior in Electric Fields of Smart Hydrogels with Potential Application as Bio-inspired Actuators, Smart Mater. Struct., 14, 511-514, 2005.
Shi Zh., Gao X., Wajid Ullah M., Li S., Wang Q., and Yang G., Electroconductive Natural Polymer-based Hydrogel, Biomaterials, 111, 40-54, 2016.
Shiga T. and Kurauchi T., Deformation of Polyelectrolyte Gels under the Influence of Electric Field, J. Appl. Polym. Sci., 39, 2305-2320, 1997.
Shamsudeen R., Jayakumari V., Rajeswari R., and Mukundan T., Polyelectolyte Hydrogels of Chitosan and Polyacrylamide: A Comparisson of Electroactive Characteristics, Indian J. Eng. Mater. Sci.,19, 331-337, 2012.
Kim S., Shin S., Lee J., Lee S., and Kim S.,Electrical Response Characterization of Chitosan/Polyacrylonitrile Hydrogel in NaCl Solutions, J. Appl. Polym. Sci., 90, 91-96, 2003.
Kim S., Park S., Kim I., Shin M., and Kim S., Electric Stimuli Responses to Poly(vinyl alcohol)/Chitosan Interpenetrating Polymer Network Hydrogel in NaCl Solutions, J. Appl. Polym. Sci., 86, 2285-2289, 2002.
Sarmad S., Yenici G., Gurkan K., Keceli G., and Gurdag G., Electric Field Responsive Chitosan–Poly(N,N-dimethyl acrylamide) Semi-IPN Gel Films and Their Dielectric, Thermal and Swelling Characterization, Smart Mater. Struct., 22, 055010-055024, 2013.
Kim S., Lee Ch., Lee Y., Kim I., and Kim S., Electrical/pH-Sensitive Swelling Behavior of Polyelectrolyte Hydrogels Prepared with Hyaluronic Acid–Poly(vinyl alcohol) Interpenetrating Polymer Networks, React. Funct. Polym.,, 55, 291-298, 2003.
O’Grady M., Kuo P., and Parker K., Optimization of Electroactive Hydrogel Actuators, ACSAppl. Mater. Interfaces, 2, 343-346, 2010.
Wu J., Ren Y., Sun J., and Feng L., Carbon Nanotube-Coated Macroporous Poly (N-isopropylacrylamide) Hydrogel and Its Electrosensitivity, ACSAppl. Mater. Interfaces, 5, 3519- 3523, 2013.
Amjadi A., Experimental Validation of Swelling Model for Dual Stimuli Sensitive (Temperature and pH) PVA/Chitosan/MMT Nanocomposite Hydrogel, MSc Thesis, Polymer Engineering Department, Tarbiat Modares University, Tehran, Iran, 2014.
Raveendran P. and Wallen F.J., Completely Green Synthesis and Stabilization of Metal Nanoparticles, J. Am. Chem. Soc., 125, 13940-13941, 2003.
Huang H. and Yang X., Synthesis of Chitosan-stabilized Gold Nanoparticle in the Absence/Presence of Tripolyphosphate, Biomacromolecules,5, 2340-2346, 2004.
Murugadoss A. and Chattopadhyay A.,A Green Chitosan-Silver Nanoparticle Composite as a Heterogeneous as Well as Micro-heterogeneous Catalyst, Nanotechnology, 19, 5603-5609, 2008.
Sanpui P., Murugadoss A., Prasad P.V.D., Ghosh S.S., and Chattopadhyay A., The Antibacterial Properties of a Novel Chitosan-Ag-Nanopartilc Composite, Int. J. Food Microbiol., 124, 142-146, 2008.
Wei D., Sun W., Qian W., Ye Y., and Ma X.,The Synthesis of Chitosan-based Silver Nanoparticle and Their Antibacterial Activity, Carbohydr. Res.,344, 2375-2382, 2009.
Venkatesham M., Ayodhya D., Madhusudhan A., Babu N. V., and Veerabhadram G.,A Novel Green One-Step Synthesis of Silver Nanoparticle Using Chitosan: Catalytic Activity and Antimicrobial Studies, Appl. Nanosci.,4, 113-119, 2014.
Zhao Y., Zhao Y., Wu X., Wang L., Xu L., and Wei Sh.,A Facile Method for Electrospinning of Ag Nanoparticle/Pol(vinyl alcohol)/Carboxymethyl-Chitosan Nanofibers, Appl. Surface Sci., 258, 8867-8873, 2012.
Thomas V., Yallapu M.M., Sreedhar B., and Bajpai S.K.,Fabrication, Characterization of Chitosan/Nanosilver Film and Its Potential Antibacterial Application, J. Biomater. Sci., 20, 2129-2144, 2009.
Hadipour-Goudarzi E., Montazer M., Latifi M., and Ghare Aghaji A., Electrospinning of Chitosan/Sericin/PVA Nanofibers Incorporated with In Situ Synthesis of Nano Silver, Carbohydr. Polym.,113, 231-239, 2014.
Salehi E. and Farahani A., Macroporous Chitosan/Polyvinyl Alcohol Composite Adsorbents Based on Activated Carbon Substrate, J. Porous Mater., 24, 1197-1207, 2017.
Shabanzadeh P., Senu N., Shameli K., Ismail F., Zamanian A., and Mohagheghtabar M., Prediction of Silver Nanoparticles’ Diameter in Montmorillonite/Chitosan Bionanocomposites by Using Artificial Neural Networks, Res. Chem. Int., 41, 3275-3287, 2015.
Cirpan A., Alkan S., Toppare L., David G., and Yagci Y., Synthesis and Elecroactivity of Pyrrole End-functionalized Poly(2-methyl-2-axazoline), Eur. Polym. J., 37, 2225-2229, 2001.
Zhang Y., Thomas Y., Kim E., and Payne G.F., pH- and Voltage-Responsive Chitosan Hydrogel through Covalent Cross-Linking with Catechol, J. Phys. Chem. B, 116, 1579 -1585, 2012.
Dispenza C., Presti C.L., Belfiore C., Spadaro G., and Piazza S., Electrically Conductive Hydrogel Composites Made of Polyaniline Nanoparticles and Poly(N-vinyl-2-pyrrolidone), Polymer, 47, 961-971, 2006.
Small C.J., Too C.O. and Wallace G.G., Responsive Conducting Polymer-Hydrogel Composites, Polym. Gels Networks, 5, 251-265, 1997.
Wang Y., Programmable Hydrogels, Biomaterials, 178, 663-680, 2018.
Kaith B.S., Jindal R., Mittal H., and Kumar K., Temperature, pH and Electric Stimulus Responsive Hydrogels from Gum Ghatti and Polyacrylamide-Synthesis, Characterization and Swelling Studies, Der Chemica Sinica, 1, 44-54, 2010.
Migliorini L., Santaniello T., and Yan Y., Lenardi C., and Milani P., Low-Voltage Electrically Driven Homeostatic Hydrogel-Based Actuators for Underwater Soft Robotics, Sensor. Actuat., B: Chem., 228, 758-766, 2016.
)
