It is challenging to design and characterize molecular recognition pair consisting of both targeting and imaging property and it is also of particular interest to inquire into the limits of the affinity that can be achieved with designed bio-conjugate. This paper presents functionalization of luminescent quantum dots (QDs) employing multivalent dendrimer molecules conjugated with biotin as targeting moiety and photo-physical and thermodynamic behavior of this bio-conjugate in terms of highly affinic binding with avidin. It is demonstrated that fluorescence intensity of QDs remained almost unaffected when synthesized conjugate interacts with avidin and this is considered to be an important requisite for applications in imaging and sensing. The observed changes in average emission lifetime as well as values of lifetime components of avidin indicate the binding of biotin with tryptophan moiety of avidin. Calorimetric investigation reveals that binding of avidin with biotin-dendrimer conjugate is exothermic process accompanied with favorable enthalpy (ΔH = −21.6 kcal/mol) and unfavorable entropy (ΔS = −43.7 cal/mol/deg). These findings may help design of multiplexed assays where dendrimer conjugated QDs based probe molecules are immobilized via the avidin-biotin interactions which can have implications in development of immuno-histochemical techniques.

设计和表征由靶向和成像特性组成的分子识别对具有挑战性，而且特别需要探究利用设计的生物共轭物可以实现的亲和力极限。本文介绍了利用与生物素偶联的多价树状聚合物分子作为靶向部分的发光量子点（QD）的功能化，以及该生物偶联物在与亲和素的高度亲和力结合方面的光物理和热力学行为。结果表明，当合成的结合物与抗生物素蛋白相互作用时，量子点的荧光强度几乎不受影响，这被认为是成像和传感应用的重要条件。观察到的平均发射寿命的变化以及抗生物素蛋白的生命成分的值表明生物素与抗生物素蛋白的色氨酸部分的结合。量热研究显示，抗生物素蛋白与生物素-树状聚合物共轭物的结合是放热过程，伴随有有利的焓（ΔH= -21.6 kcal / mol）和不利的熵（ΔS= -43.7 cal / mol / deg）。这些发现可能有助于设计多重化分析，其中固定了基于树枝状聚合物的QDs探针分子通过抗生物素蛋白-生物素的相互作用可能对免疫组织化学技术的发展有影响。