Tunable pores for measuring concentrations of synthetic and biological nanoparticle dispersions.
Scanning ion occlusion sensing (SIOS), a technique that uses a tunable pore to detect the passage of individual nano-scale objects, is applied here for the rapid, accurate and direct measurement of synthetic and biological nanoparticle concentrations. SIOS is able to characterize smaller particles than other direct count techniques such as flow cytometry or Coulter counters, and the direct count avoids approximations such as those necessary for turbidity measurements. Measurements in a model system of 210-710 nm diameter polystyrene particles demonstrate that the event frequency scales linearly with applied pressure and concentration, and that measured concentrations are independent of particle type and size. Both an external-calibration and a calibration-free measurement method are demonstrated. SIOS is then applied to measure concentrations of Baculovirus occlusion bodies, with a diameter of ~1 μm, and the marine photosynthetic cyanobacterium Prochlorococcus, with a diameter of ~600 nm. The determined concentrations agree well with results from counting with microscopy (a 17% difference between the mean concentrations) and flow cytometry (6% difference between the mean concentrations), respectively.
Izon Science Ltd, PO Box 39168, Harewood, Christchurch 8545, New Zealand.
G Seth
GS
Roberts
Sam
S
Yu
Qinglu
Q
Zeng
Leslie C L
LC
Chan
Will
W
Anderson
Aaron H
AH
Colby
Mark W
MW
Grinstaff
Steven
S
Reid
Robert
R
Vogel
D001704:Biopolymers / Q000032:analysis*; D015374:Biosensing Techniques / Q000295:instrumentation*; D003102:Colloids / Q000032:analysis; D003217:Conductometry / Q000295:instrumentation*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D008567:Membranes, Artificial; D008832:Microchemistry / Q000295:instrumentation; D053758:Nanoparticles / Q000032:analysis*; D016062:Porosity; D014462:Ultrafiltration / Q000295:instrumentation*
D001704:Biopolymers; D003102:Colloids; D008567:Membranes, Artificial