ResearchArticle Functionalized-AgNPs for Long-Term Stability and Its Applicability in the Detection of Manganese Ions Van-Tuan Hoang , 1,2,3 Mai Mai, 1 LeThiTam, 1 NgocPhanVu, 2,3 Nguyen Tien Khi, 2,3 Phuong Dinh Tam , 4 Tran Quang Huy, 2,5 Anh-Tuan Le , 2,4 Ngo Xuan Dinh, 6 and Vinh-Hoang Tran 7 1 Advanced Institute for Science and Technology (AIST), Hanoi University of Science and Technology (HUST), 1 st Dai Co Viet Road, Hanoi, Vietnam 2 Phenikaa University Nano Institute (PHENA), Phenikaa University, Hanoi 12116, Vietnam 3 Faculty of Biotechnology, Chemistry and Environmental Engineering, Phenikaa University, Hanoi 12116, Vietnam 4 Faculty of Materials Science and Engineering, Phenikaa University, Hanoi 12116, Vietnam 5 Faculty of Electric and Electronics, Phenikaa University, Hanoi 12116, Vietnam 6 University of Transport Technology, anh Xuan District, Hanoi 12116, Vietnam 7 SchoolofChemicalEngineering,HanoiUniversityofScienceandTechnology(HUST),1 st DaiCoVietRoad,Hanoi,Vietnam Correspondence should be addressed to Van-Tuan Hoang; tuan.hoangvan@phenikaa-uni.edu.vn and Anh-Tuan Le; tuan.leanh@ phenikaa-uni.edu.vn Received 6 August 2019; Revised 2 December 2019; Accepted 3 January 2020; Published 7 February 2020 Academic Editor: Gyorgy Szekely Copyright©2020Van-TuanHoangetal.isisanopenaccessarticledistributedundertheCreativeCommonsAttributionLicense, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. In this study, silver nanoparticles (AgNPs) were functionalized by various molecules, including sodium borohydride (NaBH 4 ), polyhexamethylene biguanide hydrochloride (PHMB), and Tween 80 to investigate the long-term stabilization of AgNPs in an aqueous dispersion. PHMB-functionalized silver nanoparticles (AgNPs/PHMB) exhibited better stability than others and could be stored at ambient temperature for at least 180 days. In addition to creating stabilization based on the electrostatic repulsion, the use of PHMB helped to increase the degree of stability of the colloidal AgNPs for a long time owing to strong interactions between Ag atoms on AgNPs with nitrogen (N) positions in PHMB molecules. e formed bond led to improving maintenance ability of the electrostatic repulsion layer among independent nanoparticles. e applicability of the as-prepared AgNPs/PHMB was also examined for Mn 2+ detection via a colorimetric approach. e calibration curve was found to be linear over the range of 0–100 mM with a correlation coefficient of 0.97. e amine groups of PHMB brought out a cooperative effect to form of ion- templated chelation with Mn 2+ , which caused the aggregation of AgNPs/PHMB. is suggested that the AgNPs/PHMB could be used as a potential probe in the detection of Mn 2+ ions. More importantly, the long-term stability of AgNPs/PHMB paved a great promising path to provide many further solutions for the producer in practical applications. 1.Introduction Silver nanoparticles (AgNPs) possess many unique chemical and physical properties; therefore, AgNPs have been widely studied and exploited in various applications, including medical, home appliances, electronics, textiles, and cosmetics [1]. e demand for AgNPs in the world is projected to increase, with production estimated at around 320 tons per year [1,2]. However, the properties of AgNPs strongly depend on their size, shape, and crystallinity. Moreover, large specific surface area and high surface energy lead to the self-aggre- gation of AgNPs during storing time, which considerably decreases their activity as well as applicability. ese indicate that the stabilization of colloidal AgNPs is one of the most essential factors for developing practical applications [3–5]. Furthermore, the use of suitable stabilizers not only helps prevent the aggregation of AgNPs but also increases their activity. erefore, many recent efforts have been performed to functionalize AgNPs by different stabilizers such as polymer or functional molecules, which contain amine Hindawi Advances in Polymer Technology Volume 2020, Article ID 9437108, 9 pages https://doi.org/10.1155/2020/9437108