Method for quantifying biomolecules conjugated to a nanoparticle

A method for quantifying protein conjugated to a nanoparticle, comprising:

• providing a bioconjugate comprising a nanoparticle having a protein conjugated thereto;
• displacing the protein conjugated to the nanoparticle to produce a displaced protein;
• and
• quantifying protein concentration spectrophotometrically using tryptophan fluorescence.

A method-for quantifying a biomolecule conjugated to a nanoparticle, comprising:

• providing a bioconjugate comprising an antibody conjugated to a quantum dot;
• heating a reaction mixture comprising the bioconjugate in a solution comprising a thiol ligand exchange compound;
• and
• measuring tryptophan fluorescence to determine antibody concentration.

A method for assessing signal generation capabilities of biomolecule-nanoparticle conjugates, comprising:

• providing a first bioconjugate and a second bioconjugate, each of the first and second bioconjugates comprising a biomolecule conjugated to a nanoparticle, the first and second bioconjugates having first and second different biomolecule-to-nanoparticle ratios that are determined by quantifying the biomolecule conjugated to the nanoparticle by first digesting the biomolecule or by forming a hybridization product of the biomolecule;
• assessing the first bioconjugate for an assay function to provide a first assessment;
• assessing the second bioconjugate for the assay function to provide a second assessment;
• and
• comparing the first and second assessments, thereby assessing signal generation capabilities of the first and second bioconjugates.

A method for quantifying protein conjugated to a nanoparticle, comprising:

• displacing, and optionally digesting, protein from a protein-nanoparticle conjugate to produce displaced protein;
• substantially separating the nanoparticle from the displaced protein;
• and
• spectrophotometrically determining a displaced protein concentration using tryptophan fluorescence.