Area density of streptavidin can be evaluated by the number density of biotinylated microbubbles

Abstract

Targeted microbubbles (TMBs) that specifically accumulate on target sites via biochemical bonds have been studied for using ultrasound diagnoses and therapies (e.g., ultrasound molecular imaging) in the research field. To understand the specific interactions between TMBs and their target molecules, a biosensor system with a quartz crystal microbalance (QCM) was constructed. In this system, TMBs become absorbed on their target molecule, which was fixed to the QCM surface via a self-assembled monolayer. Our previous studies showed that the system allowed the evaluation of the interaction between biotinylated MBs and the target molecule, streptavidin, by monitoring changes in the resonant frequency of QCM [Muramoto et al., Ultrasound Med. Biol., 40(5), 1027–1033 (2014)]. This paper investigates how the amount of streptavidin relates to the amount of absorbed biotinylated MBs. The amount of streptavidin on the QCM surface was evaluated by measuring the difference in its resonant frequency before and after the fixation of streptavidin. After which, the amount of absorbed MBs was also evaluated by measuring the frequency shift during the interaction between MBs and the target molecule. Our results showed a weak correlation between the amounts of bound MB and the density of streptavidin (correlation coefficient, r = 0.44), suggesting that the area density of target molecule can be evaluated by estimating the number density of TMBs.

Adsorption and Desorption of a Phospholipid from Single Microbubbles under Pulsed Ultrasound Irradiation for Ultrasound-Triggered Drug Delivery

“…Here, we investigated the adsorption and desorption characteristics of DMPC from single bubbles, tens of micrometers in size, using an instrument based on an ultrasound transducer and a high-speed camera. the solution because the surface of DMPC bubbles can be modified through the polyethylene glycol [37,38].…”

“…In consideration of applications in clinical research, we added 132 mg of polyethylene glycol monostearate [CH 3 (CH 2 ) 16 COO­(CH 2 CH 2 O) 2 H; Fujifilm Wako Pure Chemical Corporation, Osaka, Japan; CAS Registry No. 106-11-6; M w value of 372.66] to the solution, because the surfaces of DMPC bubbles can be modified through the polyethylene glycol. , …”

“…106-11-6; M w value of 372.66] to the solution, because the surfaces of DMPC bubbles can be modified through the polyethylene glycol. 37,38 Figure 1 shows the optical observational system. A bolt-clamped Langevin-type ultrasound piezoelectric transducer with a resonance frequency of 38.8 kHz (Fuji Ceramics, Fujinomiya, Japan) was fitted to the bottom of a rectangular transparent cell (75 × 75 × 60 mm 3 ).…”