Development of simple, facile, and on-spot colorimetric assays for drugs and pesticides based on metal nanoparticles is an emerging field of modern scientific research. Herein, a branched polyethyleneimine (PEI) is used to stabilize silver nanoparticles (AgNPs) through a simple one-pot, two-phase protocol. As the primary goal of the research, the synthesized PEI-AgNPs are employed for an efficient and selective quantitative detection of promethazine (PRO). The typical yellow color of PEI-AgNPs changed to orangish-brown as soon as PRO is added which is further endorsed by an increase in the intensity of the SPR band. The electrostatic forces are responsible for the steric stabilization of silver ions in the micro-domains of the PEI. PRO addition in PEI-AgNPs decreased the average hydrodynamic size and increased apparent positive charge of AgNPs. These changes might be attributed to the presence of the sulfur group in PRO. The limit of detection, the limit of quantification, and the dynamic range of detection of PRO through PEI-AgNPs are found to be 0.003 μM, 0.1 μM, and 0.1–200 μM, respectively. Moreover, PEI-AgNPs allowed reliable, efficient, selective, and quick quantitative detection of PRO in environmental, biological, and commercial drug samples in the presence of other interfering drugs and metal salts. The proposed PRO sensor renders an excellent platform for its quick and on-spot detection without requiring a well-equipped lab setup. Up to the best of our knowledge, the proposed PRO sensor is the first of its kind (colorimetric) in the list of proposed instrumental methods for determination of PRO. The quantitation of PRO as obtained by proposed sensor is compared with UV–Vis spectroscopy and UPLC. Finally, excellent performance of PEI-AgNPs based sensor for biological, environmental, and commercial samples is demonstrated in comparison to UV–Vis spectroscopy and UPLC.

开发基于金属纳米粒子的药物和农药的简单、简便和现场比色测定是现代科学研究的一个新兴领域。在此，支链聚乙烯亚胺 (PEI) 用于通过简单的一锅两相协议稳定银纳米粒子 (AgNPs)。作为研究的主要目标，合成的 PEI-AgNPs 用于高效和选择性地定量检测异丙嗪 (PRO)。一旦添加 PRO，PEI-AgNPs 的典型黄色就会变成橙棕色，这进一步得到了 SPR 带强度增加的认可。静电力负责银离子在 PEI 的微域中的空间稳定性。PEI-AgNPs 中的 PRO 添加降低了平均流体动力学尺寸并增加了 AgNPs 的表观正电荷。这些变化可能归因于 PRO 中硫基的存在。通过 PEI-AgNPs 检测 PRO 的检测限、定量限和动态范围分别为 0.003 μM、0.1 μM 和 0.1-200 μM。此外，PEI-AgNPs 允许在存在其他干扰药物和金属盐的情况下，对环境、生物和商业药物样品中的 PRO 进行可靠、高效、选择性和快速的定量检测。拟议的 PRO 传感器为其快速和现场检测提供了一个极好的平台，而无需设备齐全的实验室设置。据我们所知，所提议的 PRO 传感器是提议的用于确定 PRO 的仪器方法列表中的第一个（比色法）传感器。将通过所提出的传感器获得的 PRO 定量与 UV-Vis 光谱和 UPLC 进行比较。最后，与 UV-Vis 光谱和 UPLC 相比，证明了基于 PEI-AgNPs 的传感器在生物、环境和商业样品中的出色性能。