New Insight into Assembled Fe(3)O(4)@PEI@Ag Structure as Acceptable Agent with Enzymatic and Photothermal Properties

Metal-based enzyme mimics are considered to be acceptable agents in terms of their biomedical and biological properties; among them, iron oxides (Fe(3)O(4)) are treated as basement in fabricating heterogeneous composites through variable valency integrations. In this work, we have established a facile approach for constructing Fe(3)O(4)@Ag composite through assembling Fe(3)O(4) and Ag together via polyethyleneimine ethylenediamine (PEI) linkages. The obtained Fe(3)O(4)@PEI@Ag structure conveys several hundred nanometers (~150 nm). The absorption peak at 652 nm is utilized for confirming the peroxidase-like activity of Fe(3)O(4)@PEI@Ag structure by catalyzing 3,3′,5,5′-tetramethylbenzidine (TMB) in the presence of H(2)O(2). The Michaelis–Menten parameters (K(m)) of 1.192 mM and 0.302 mM show the higher catalytic activity and strong affinity toward H(2)O(2) and TMB, respectively. The maximum velocity (V(max)) value of 1.299 × 10(−7) M∙s(−1) and 1.163 × 10(−7) M∙s(−1) confirm the efficiency of Fe(3)O(4)@PEI@Ag structure. The biocompatibility illustrates almost 100% cell viability. Being treated as one simple colorimetric sensor, it shows relative selectivity and sensitivity toward the detection of glucose based on glucose oxidase. By using indocyanine green (ICG) molecule as an additional factor, a remarkable temperature elevation is observed in Fe(3)O(4)@PEI@Ag@ICG with increments of 21.6 °C, and the absorption peak is nearby 870 nm. This implies that the multifunctional Fe(3)O(4)@PEI@Ag structure could be an alternative substrate for formatting acceptable agents in biomedicine and biotechnology with enzymatic and photothermal properties.