Specific interactions between ligands and receptors on cell surface play an important role in the cell biological process. Nucleic acid aptamers as commonly used ligands enable specific recognition and tight binding to membrane protein receptors for modulation of cell fate. Therefore, molecular probes with aptamers can be applied for cancer diagnosis and targeted therapy by targeting overexpression membrane proteins of cancer cells. However, because of their fast degradation and rapid glomerulus clearance in vivo, the applications of aptamers in physiological conditions remain challenged. Inspired by natural multivalent interactions, many approaches have been developed to construct multivalent aptamers to improve the performance of aptamers in complex matrices with higher binding affinity, more stability, and longer circulation time. In this review, we first introduce the aptamer generation from purified protein-based SELEX and whole cell-based SELEX for targeting the cell surface. We then highlight the approaches to fabricate multivalent aptamers and discuss their properties. By integrating different materials (including inorganic nanomaterials, diacyllipid, polymeric nanoparticles, and DNA nanostructures) as scaffolds with an interface modification technique, we have summarized four kinds of multivalent aptamers. After that, representative applications in biosensing and targeted therapy are illustrated to show the elevated performance of multivalent aptamers. In addition, we analyze the challenges and opportunities for the clinical practices of multivalent aptamers.

PurposeThe relationship between debt and happiness is an emerging research topic with significant implications for both theory and practice in economics and business. In China, where the consumer credit market is at an early stage of development, the topic remains under-investigated and the evidence on the debt–well-being link is scarce. The purpose of this study is to examine the association between debt holding and happiness and the moderating role of income in it.Design/methodology/approachData used in the study were from three waves (2013, 2015 and 2017) of the China Household Finance Survey. Fixed-effect regressions on panel data were used for data analyses.FindingsThe results show that any type of debt holding is negatively associated with happiness. Among seven specific types of debts, four types show negative associations with happiness, which in the order from higher to lower associations, are medical, education, other and housing debt. In addition, negative associations between debt holding and happiness vary among income groups. The results suggest that any debt holding potentially decreases happiness for low- and middle-income consumers only. In addition, holdings of three specific types of debts (medical, education and housing debt) may decrease happiness for both low- and middle-income consumers, and holding two types of debts (business and other debt) may decrease happiness for middle-income consumers only.Research limitations/implicationsData used in this study originate from one country only. It limits the generalizability of findings to other countries with different institutional backgrounds and different socio-economic characteristics of populations. The results have implications for researchers who study consumer debt behavior and business practitioners who do businesses with Chinese companies and consumers.Practical implicationsChina is an emerging economy that is at the early stage of credit market development. The results of this study provide helpful information and insights for business practitioners to explore credit markets and serve credit product clients with various income levels in China.Social implicationsThe results of this study are informative for public policies. When introducing credit market-related policies, policymakers should pay attention to people's happiness and to differential welfare effects of holdings of different types of debts and among consumers with various levels of incomes.Originality/valueUnique contributions of this study include using data from the most recently available waves of the China Household Finance Survey (2013, 2015 and 2017) to study the associations between debt holding and happiness. In addition, the findings of this study enrich the literature of debt and happiness by adding evidence from China, the largest emerging economy in the world, which is helpful for future theory building and business practice on the relationship between debt holding and happiness.

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Fluorescence microscopy has evolved from a purely biological tool to a powerful chemical instrument for imaging and kinetics research of nanocatalysis. And the demand for high signal-to-noise ratio and temporal-spatial...