Quantum Dot Self-Assembly for Protein Detection with Sub-Picomolar Sensitivity

Abstract

A novel approach to sensitive and rapid antigen detection is described. In the presence of a specific antigen, quantum dot-antibody conjugates rapidly self-assemble into agglomerates that are typically more than 1 order of magnitude larger than their individual components. The size distribution of the agglomerated colloids depends on, among other things, the relative concentration of quantum dot conjugates and antigen molecules. Quantum dot agglomerates mediated by antigen recognition were characterized by measuring their light scattering and fluorescence characteristics in an unmodified flow cytometer. Protein antigens angiopoietin-2 and mouse IgG were detected to sub-picomolar concentrations using this method. This simple technique enables the potential simultaneous detection of multiple antigenic biomarkers directly from physiological media and could be used for early detection and frequent screening of cancers and other diseases.

Nanomaterials in fluorescence-based biosensing

“…In this scheme, QD-Ab conjugates rapidly aggregate in the presence of antigens, resulting in colloidal structures that are 1-2 orders of magnitude larger in size than the constituents [9]. These structures are detected by light scattering in a flow cytometer [9]. The detection of various antigens using QDs with different emission properties is possible with this straightforward agglomeration-based detection strategy.…”

“…Since the interaction between CrAsH and cysteine causes a significant increase in CrAsH's fluorescence, nanohybrids of CrAsH-QD could serve as a probe to locate Cys-tagged proteins and subsequently trace them for more than 150 s, taking advantage of the high resistance of QDs to photobleaching [8]. On the other hand, Soman et al profited from the much larger size of QDs than organic dyes when designing a protein detection scheme that offers subpicomolar sensitivity [9]. In this scheme, QD-Ab conjugates rapidly aggregate in the presence of antigens, resulting in colloidal structures that are 1-2 orders of magnitude larger in size than the constituents [9].…”

“…On the other hand, Soman et al profited from the much larger size of QDs than organic dyes when designing a protein detection scheme that offers subpicomolar sensitivity [9]. In this scheme, QD-Ab conjugates rapidly aggregate in the presence of antigens, resulting in colloidal structures that are 1-2 orders of magnitude larger in size than the constituents [9]. These structures are detected by light scattering in a flow cytometer [9].…”

Quantum‐dots‐based fluoroimmunoassay for the rapid and sensitive detection of avian influenza virus subtype H5N1

“…4, the RLS intensity of QDs-rabbit anti-AIV H5N1 antibody was remarkably increased in the presence of H5N1 viral antigen, which showed that larger particles were formed based on the immunoreaction between H5N1 viral antigen and the QDs-rabbit anti-AIV H5N1 antibody probe. (19) Further evidence for the eff ect of QDs-rabbit anti-AIV H5N1 antibody probe was also confi rmed by FL imaging. Figure 5 showed two FL imagings from the sandwich conjugates bound on microplates after sFLISA.…”

Recent Patents on Nanosensor for Tumor Biomarker Detection

“…Additional embodiments include the use of the same device to detect alternate biomarkers associated with response to therapy, which reduces patient exposure to ineffective therapies, minimize the development of ntion includes monitoring disease relapse following successful treatment in a sensitive and rapid way at the 'point-of-care', effectively addressing a critical concern shared by all cancer survivors [9].…”