Measurement of Nanoparticle Concentration Using Quartz Crystal Microgravimetry

Abstract

Various nanoscale items (e.g., nanoparticles and nanotubes) have been actively investigated due to their unique physicochemical properties. A common issue encountered in such studies is accurate expression of nanoparticle concentration. Given the critical importance of the dose-response relationship, we present the use of quartz crystal microgravimetry (QCM) to accurately measure nanoparticle concentration in a colloidal suspension. Application of a small drop of the nanoparticle suspension in a volatile solvent to the crystal surface leaves a dry nanoparticle residue after solvent evaporation after which the shift in the crystal resonant frequency is recorded. The instrument was calibrated using a set of serial dilutions of Si and Ag nanopowder in methanol, rhodamine B in methanol, and ferrocene in cyclohexane. Using QCM, a linear response for nanoparticle concentrations up to 1300 μg/mL was determined. The developed method was used to determine the concentrations of size-selected, octyl-terminated Si nanocrystal samples with median diameters in the range 1.1-14.8 nm and also to calculate size-dependent nanocrystal extinction coefficients.

Methods for Measuring Concentration (Mass, Surface Area and Number) of Nanomaterials

“…QCM is a direct and sensitive technique to quantify mass concentration of nanocrystals without interference from size or surface of the NMs. 48 Typically, a liquid drop of the NM solution is deposited on one face of an oscillating crystal. The dry residue mass of NMs after solvent evaporation (Dm) is detected as a change in resonant frequency (Df ) of the quartz crystal, according to the Sauerbrey equation.…”

A Simple Method for the Detection of Long-Chain Fatty Acids in an Anaerobic Digestate Using a Quartz Crystal Sensor

“…Based on the average frequency-shift rates in Figure 3b, there is a high correlation (R 2 = 0.9929) between the rates and palmitate concentrations within 0-100 mg/L. Within the linear range, Saueberey's Equation (2) is established [29]. ∆m = −C·∆f (2) In this equation, there is a linear relation between mass change on the electrode (∆m) and frequency shift (∆f ).…”

“…Several studies dealing with QCM sensors have presented a very good linear correlation in frequency shift versus concentrations of target substances within a specific range [27][28][29]. In this study, the linearity in the frequency-shift rate versus solution concentration was evaluated using different concentrations of palmitic acid solutions at pH 10.7.…”

“…Based on the average frequency-shift rates in Figure 3b, there is a high correlation (R 2 = 0.9929) between the rates and palmitate concentrations within 0-100 mg/L. Within the linear range, Saueberey's Equation (2) is established [29]. …”

Quantitative measurement of p53-p53 antibody interactions by quartz crystal microbalance: A modelsystem for immunochemical calibration

“…However, quantification of these assays requires direct measurement of the concentration of the surface bound p53 and the antibodies. For this we have developed a model system for characterizing p53 antibodies using a quartz crystal microbalance (QCM) [2]. Our application of the previously described QCM method [3,4] provides independent quality control of the reagents used in IHC with particular regard to the antibody sensitivity and specificity [5].…”