Thossaporn Wijakmatee

A portable, battery‐powered, multi‐purpose readout system for combined optical and thermal measurements is presented. The system is modular with four independent input channels for different measurement schemes, allowing simultaneous multi‐parameter measurements to detect analytes of interest. Combined optical and thermal readout for spectroscopy is implemented by installing two different analog front‐end modules in the four input channels equipped with a micro spectrometer and a high‐resolution temperature sensor, respectively. The readout system is utilized to measure fluorescence signals of a common dye functionalized on gold nanoparticle‐DNA conjugates as a function of the temperature. Gold nanoparticles are modified with Guanine‐rich DNA sequences to perform Förster Resonance Energy Transfer (FRET) measurements. Elongation of DNA sequences at higher temperatures resulted in stronger fluorescence signals, accurately recorded by the portable system. The precision electronic components are chosen for a precise, battery‐powered operation. The size of this versatile, compact, and portable instrument is only 15.6 × 10.6 cm². An interactive graphical‐user‐interface developed for this system supports point‐of‐care usage. The measurements carried out with the portable system showed a very close match with a commercial set‐up, with deviations less than 1 nm in the optical spectra and less than 0.5 °C in temperature.

Hydrothermal synthesis of surface-modified magnetitenanoparticles(NPs) was performed in a batch reactor at 200 & DEG;C for 20 min whileusing monocarboxylic acid with various alkyl chain lengths (C6 toC18) as surface modifiers. The short-chain cases (C6 to C12) successfullygave the surface-modified NPs with uniform shape and magnetite structure,while the long-chain cases (C14 to C18) gave the NPs with nonuniformshape and two structures (magnetite and hematite). Additionally, thesynthesized NPs were revealed to have single crystallinity, high stability,and ferromagnetic property, which were useful for hyperthermia therapyvia various characterization techniques. These investigations wouldguide the selection guidelines for a surface modifier to control thestructure, surface, and magnetic properties of surface-modified magnetiteNPs with high crystallinity and stability, particularly for hyperthermiatherapy applications.

We applied the supercritical CO ₂ technology, which is an excellent solventless process, to the synthesis of surface-modified iron oxide nanocrystals.