title: Method for determination of polyethylene glycol molecular weight.
abstract: A method utilizing competitive adsorption between polyethylene glycols (PEGs) and labeled protein to nanoparticles was developed for the determination of PEG molecular weight (MW) in a microtiter plate format. Two mix-and-measure systems, time-resolved luminescence resonance energy transfer (TR-LRET) with donor europium(III) polystyrene nanoparticles and acceptor-labeled protein and quenching with quencher gold nanoparticles and fluorescently labeled protein were compared for their performance. MW is estimated from the PEG MW dependent changes in the competitive adsorption properties, which are presented as the luminescence signal vs PEG mass concentration. The curves obtained with the TR-LRET system overlapped for PEGs larger than 400 g/mol providing no information on MW. Distinctly different curves were obtained with the quenching system enabling the assessment of PEG MW within a broad dynamic range. The data was processed with and without prior knowledge of the PEG concentration to measure PEGs over a MW range from 62 to 35,000 g/mol. The demonstration of the measurement independent of the PEG concentration suggests that the estimation of MW is possible with quenching nanoparticle system for neutrally charged and relatively hydrophilic polymeric molecules widening the applicability of the simple and cost-effective nanoparticle-based methods.
authors.affiliation: Department of Cell Biology and Anatomy and Medicity Research Laboratory, Institute of Biomedicine, University of Turku, Kiinamyllynkatu 10, 20520 Turku, Finland.
authors.forename: Sari
authors.initials: S
authors.lastname: Pihlasalo
authors.affiliation: Department of Cell Biology and Anatomy and Medicity Research Laboratory, Institute of Biomedicine, University of Turku, Kiinamyllynkatu 10, 20520 Turku, Finland.
authors.forename: Pekka
authors.initials: P
authors.lastname: Hänninen
authors.affiliation: Department of Cell Biology and Anatomy and Medicity Research Laboratory, Institute of Biomedicine, University of Turku, Kiinamyllynkatu 10, 20520 Turku, Finland.
authors.forename: Harri
authors.initials: H
authors.lastname: Härmä
mesh_terms: D000327:Adsorption; D005063:Europium / Q000737:chemistry; D008163:Luminescent Measurements / Q000379:methods*; D008970:Molecular Weight; D053758:Nanoparticles / Q000737:chemistry; D011092:Polyethylene Glycols / Q000032:analysis* / Q000737:chemistry*; D011137:Polystyrenes / Q000737:chemistry; D011506:Proteins / Q000032:analysis; D013499:Surface Properties; D013997:Time Factors
chemical_list: D011137:Polystyrenes; D011506:Proteins; D011092:Polyethylene Glycols; D005063:Europium