This paper presents the construction and characterization of an amperometric immunosensor based on the graphene/gold nanoparticles (AuNPs/GO) nanocomposite for the detection of the bladder cancer biomarker, apolipoprotein A1 (Apo-A1). The morphological analysis of the AuNPs/GO nanocomposite demonstrated an almost spherical shape of AuNPs and the successful coverage of their surface by graphene oxide. An increased G peak and decreased D peak after the association of AuNPs with GO, implied a reduction in graphene defects. The X-ray photoelectron spectroscopy (XPS) indicated a significant decrease in the quantity of oxygen-containing functional groups in the AuNPs/GO nanocomposite, as compared to the original GO. Furthermore, the developed sensor demonstrated commendable sensitivity and selectivity, with a wide linear range for Apo-A1 detection. Importantly, the immunosensor exhibited remarkable stability over a period of 14 days, signifying its potential for practical applications.

Compared with the research on consumer engagement in brand community, the research on consumer engagement in brand public has been relatively less. This research aimed at exploring how brand public characteristics such as information variety, various communications and no limitation in expressing self affect the brand public engagement. 274 questionnaires answered by Chinese consumers are used to conduct analysis. Principal component analysis is used to test the reliability and validity of each construct, and structural equation model is used to test hypotheses. The study finds the positive effects of information variety on information benefits, those of various communications on social benefits, and also positive roles of no limitation in expressing self to brand-related self-expression motivation. And each of the information benefits, social benefits and brand-related self-expression motivation is proved to positively affect brand public engagement. The study implies that marketers should give attention to characteristics of brand public, and provide the ways by which members of brand public engage the brand. Additionally, marketers should pay more attention to both direct and indirect engagement activities of consumers toward brand public in social media to better understand their target consumers.

With the increasingly mature development of China's Internet technology, China's e-commerce has developed, which has given a huge boost to China's economic growth. In recent years, mobile payment has become a bright spot in China's economy, promoting the further development of e-commerce. On the one hand, various e-commerce sales and service platforms in China have greatly developed and with Alibaba as the representative, the annual turnover of e-commerce sales platform has increased year by year. On the other hand, with the implementation of the "one belt and one way" policy, cross-border electricity providers have promoted China's trade with the world and become China's new economic growth point. This paper analyzes the current situation of e-commerce in China and puts forward Suggestions for the further development of e-commerce in China.