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Simultaneous optical and magnetophoretic monitoring of DNA hybridization using superparamagnetic and plasmonic colloids.

ABSTRACT: The detection and separation of small biomolecules from complex mixtures and the possibility of their recovering for further analyses have great benefits for the early diagnosis and prognosis of diseases. Developing simple, sensitive, and cost-effective tools that allow the rapid and accurate assembly and isolation of molecular biomarkers has the potential to improve both patient care and hospital logistic efficiency towards personalized and affordable treatments of diseases.In this work, we presenta method consisting ofUV-vis-spectroscopy assisted-magnetophoresis for the monitoring of DNA hybridization. For this purpose, a magnetic device generating 7.5?T/m uniform magnetic field gradient was designed and incorporated to a commercial spectrophotometer. Different batches of colloidal superparamagnetic particles (SMPs), with different elemental compositions, were functionalized with twenty-mer complementary oligonucleotides, TB1 and TB2. When the functionalized SMPs-TB1 and SMPs-TB2 are mixed and incubated, the hybridization process of TB1 and TB2 occurs resulting in the formation of colloidal aggregates. When brought under the magnetic field, depending on the magnetic strength (?) of the formed aggregates, they separate either faster or slower than the non-functionalized SMPs. The difference in magnetic separation time (?t) is optically monitored by measuring the real time transparency of the suspension at specific wavelengths. The detection of aggregates at concentrations of 0.001% w/v was achieved, showing ?t ranging from 113-228?s. Based on the changes of ?t, the study addresses how electrosteric, magnetic, and hydrogen bonding interactions affect the hybridization process and suggests optimum experimental conditions for accurate monitoring of TB1-TB2 hybridization.

SUBMITTER: Benelmekki M

PROVIDER: S-EPMC7228730 | biostudies-literature | 2020 Sep

REPOSITORIES: biostudies-literature

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Simultaneous optical and magnetophoretic monitoring of DNA hybridization using superparamagnetic and plasmonic colloids.

Benelmekki Maria M Gasso Sergi S Martinez Lluis M LM

Colloids and surfaces. B, Biointerfaces 20200515

The detection and separation of small biomolecules from complex mixtures and the possibility of their recovering for further analyses have great benefits for the early diagnosis and prognosis of diseases. Developing simple, sensitive, and cost-effective tools that allow the rapid and accurate assembly and isolation of molecular biomarkers has the potential to improve both patient care and hospital logistic efficiency towards personalized and affordable treatments of diseases.In this work, we pre ...[more]

PMID: 32422560

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Project description:The control of temperature during photothermal therapy is key to preventing unwanted damage in surrounding tissue or post-treatment inflammatory responses. Lack of accurate thermal control is indeed one of the main limitations that hyperthermia techniques present to allow their translation into therapeutic applications. We developed a nanoprobe that allows controlled local heating, combined with in situ nanothermometry. The design of the probe follows a practical rationale that aims at simplifying experimental requirements and exploits exclusively optical wavelengths matching the first and second biological windows in the near-infrared. Methods: Hybrid nanostructures were chemically synthesized, and combine gold nanostars (photothermal agents) with CaF2:Nd3+,Y3+ nanoparticles (luminescent nanothermometers). Both components were simultaneously excited in the near-infrared range, at 808 nm. Following the goal of simplifying the thermal monitoring technique, the luminescent signal was recorded with a portable near-infrared detector. The performance of the probes was tested in 3D tumor spheroids from a human glioblastoma (U87MG) cell line. The location of the beads within the spheroids was determined measuring Nd3+ emission in a commercial Lightsheet microscope, modified in-house to be able to select the required near-infrared wavelengths. The temperature achieved inside the tumor spheroids was deduced from the luminescence of Nd3+, following a protocol that we developed to provide reliable thermal readings. Results: The choice of materials was shown to work as an optically excited hybrid probe. Depending on the illumination parameters, temperature can be controlled in a range between 37 ºC and 100 ºC. The near-infrared emission of nanothermometers also allows microscopic tracking of the hybrid nanostructures, confirming that the probes can penetrate deeper into the spheroid mass. We observed that, application of optical thermometry in biological environments requires often neglected considerations, since the optical signal changes along the optical path. Accordingly, we developed data analysis protocols that guarantee reliable thermal readings. Conclusions: The prepared hybrid probes are internalized in 3D tumor spheroids and can be used to induce cell death through photothermal effects, while simultaneously measuring the local temperature in situ. We show that luminescent thermometry in biomedical applications requires the development of protocols that guarantee accurate readings. Regarding photothermal treatments, we observe a sharp thermal threshold at around 55 ºC (for 10 min treatments) that separates high survival ratio from complete cell death.

Dataset Information

Simultaneous optical and magnetophoretic monitoring of DNA hybridization using superparamagnetic and plasmonic colloids.

Publications

Simultaneous optical and magnetophoretic monitoring of DNA hybridization using superparamagnetic and plasmonic colloids.

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