Aptamers are short and single-stranded DNA or RNA molecules with highly programmable structures that give them the ability to interact specifically with a large variety of targets, including proteins, cells, and small molecules. Multivalent aptamers refer to molecular constructs that combine two or more identical or different types of aptamers. Multivalency increases the avidity of aptamers, a particularly advantageous feature that allows for significantly increased binding affinities in comparison with aptamer monomers. Another advantage of multivalency is increased aptamer stabilities that confer improved performances under physiological conditions for various applications in clinical settings. The current study aims to review the most recent developments in multivalent aptamer research. The review will first discuss structures of multivalent aptamers. This is followed by detailed discussions on design strategies of multivalent aptamer approaches. Finally, recent developments of the multivalent aptamer approach in biosensing and biomedical applications are highlighted.
Grey correlation analysis uses grey correlations to describe the strength, magnitude, and order of relationships among factors. The data sequence of the drmined data is used as a reference data string, and the data sequence matrix of each influence factor is used as a control data matrix to calculate the correlation between the data sequence and the reference of each factor in the control data matrix. The basic idea of quantitatively measuring the correlation between each factor and the object is to determine the similarity between the reference data sequence and the shape of multiple comparison data sequences and to determine whether the connection is strong. It reflects the degree of correlation between curves. In this paper, we examine the problem of evaluating the quality of undergraduate education by multiple indicators and establish a comprehensive evaluation model of the quality of undergraduate education in the 13 prefecture level cities by using the grey correlation analysis. The correlation coefficient of each index was obtained by the grey correlation analysis, the correlation number of each index was analyzed and ranked, and finally the improvement of the number of “advanced teachers” and the education of 13 prefectures were reduced as much as possible.
Spinal cord injury (SCI) is a central nervous disorder that can result in permanent motor and sensory damage due to a severed communication pathway. Although there is currently no effective treatment, nerve guide tubes have been used to bridge the injured stumps and act as drug delivery systems. In this study, biosynthesized cellulose (BC) nerve guides were prepared, and nerve growth factor (NGF)—a model growth factor—was incorporated into the tubular nerve guide in order to obtain a nerve guide/drug delivery system to assist the regeneration. To achieve this, Gluconacetobacter hansenii was cultivated in a special bioreactor to produce biosynthesized cellulose tubes (BCTs) in situ, and the physical and mechanical properties of the BCTs obtained from different cultivation time points were evaluated. Our results showed that the properties of the BCTs were comparable to those of the native human neural tissues, and that the NGF released from the BCTs was bioactive for at least 7 days as evaluated by PC12 cell cultures in vitro. In summary, this study evaluated the use of BCT as a drug releasing nerve guide, and our results showed that the BCT is an attractive strategy to enhance nerve regeneration after the SCI.
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