No abstract

Antibodies are a class of molecules widely used in bioengineering and nanomedicine for applications involving protein recognition and targeting. Here we report an efficient method for universal conjugation of antibodies to lipid-coated nanoparticles using radially oriented FcγRIs. This method is performed in physiological solution with no additional coupling reagents, thereby avoiding problems with antibody stability and functionality. Coupling to the Fc region of the antibody avoids aggregation and polymerization allowing high yield. In addition, the antibody is oriented perpendicular to the surface so that the binding sites are fully functional. Using this method we demonstrate quantitative profiling of a panel of four membrane-bound cancer biomarkers (claudin-4, mesothelin, mucin-4, and cadherin-11) on four cell lines (Panc-1, MIA PaCa-2, Capan-1, and HPDE). We show that by designing the lipid coating to minimize aggregation and nonspecific binding, we can obtain absolute values of biomarker expression levels as number per unit area on the cell surface. This method is applicable to a wide range of technologies, including solution based protein detection assays and active targeting of cell surface membrane biomarkers.

Here we report on the synthesis of CdSe quantum dots from a noncoordinating solvent. We show that nucleation and growth is very fast and is completed within 100 s. The subsequent increase in average particle size is due to diffusion limited coarsening. Growth and coarsening can be quenched by injection of dodecanethiol. Finally, we compare the size distribution obtained from analysis of the absorption edge with the size distribution obtained from analysis of transmission electron microscope images.

The water solubilization of nanoparticles is key for many applications in biomedicine. Despite the importance of surface functionalization, progress has been largely empirical and very few systematic studies have been performed. Here we report on the water solubilization of QDs using lipid encapsulation. We systematically evaluate the monodispersity, zeta potential, stability, and quantum yield (QY) for QDs encapsulated with single and double acyl chain lipids, pegylated double acyl chain lipids, and single alkyl chain surfactant molecules with charged head groups. We show that charged surfactants and pegylated lipids are important to obtain monodisperse suspensions with high yield and excellent long-term stability.

Applications in nanomedicine, such as diagnostics and targeted therapeutics, rely on the detection and targeting of membrane biomarkers. In this paper we demonstrate absolute quantitative profiling, spatial mapping, and multiplexing of cancer biomarkers using functionalized quantum dots. We demonstrate highly selective targeting molecular markers for pancreatic cancer with extremely low levels of non-specific binding. We confirm that we have saturated all biomarkers on the cell surface, and, in conjunction with control experiments, extract absolute quantitative values for the biomarker density in terms of the number of molecules per square micrometer on the cell surface. We show that we can obtain quantitative spatial information of biomarker distribution on a single cell, important since tumors cell populations are inherently heterogeneous. We validate our quantitative measurements (number of molecules per square micron) using flow cytometry and demonstrate multiplexed quantitative profiling using color-coded quantum dots.