Smart “Turn‐on” Magnetic Resonance Contrast Agents Based on Aptamer‐Functionalized Superparamagnetic Iron Oxide Nanoparticles

Abstract

Smart agents. A contrast agent was designed by combining target specific nucleic‐acid aptamers against adenosine with superparamagnetic iron oxide nanoparticles. Target‐induced disassembly of clustered nanoparticles in the presence of adenosine led to an increase in T2, which was seen as an increase in the brightness of the magnetic resonance image (see figure).

Aptamer-based biosensors for biomedical diagnostics

“…Fortunately, it has been demonstrated on many occasions that aptamers still selectively recognize their targets and are relatively immune to nonspecific interactions in serum. [104][105][106] This is not surprising since natural riboswitches work well in the cellular environment. Many of the sensors are demonstrated in simple buffers, while blood, serum, urine and saliva are the most common biomedical samples; they are complex with strong optical interference.…”

Blu-ray based optomagnetic aptasensor for detection of small molecules

“…Magnetic nanoparticles (MNPs) have been widely used in biosensing for detection of various biomolecules such as nucleic acids (Göransson et al 2010;Josephson et al 2001;Liong et al 2013;Zhang et al 2013b), proteins (Aurich et al 2006;Liang et al 2011;Ranzoni et al 2012;Zhang et al 2013a), enzymes (Bamrungsap et al 2011), cells (Herr et al 2006) and small molecules (Sun et al 2006;Wu et al 2011;Yigit et al 2007;Zhang et al 2009). Due to the low magnetic susceptibility of biological compounds, the manipulation and detection of MNPs in biological media are not susceptible to interference from magnetic background, and this allows for the efficient and sensitive detection of biomolecules without the need for sample purification steps.…”

“…Therefore, target binding-induced cluster disassembly strategies have been pursued using a competitive binding assay format (Sun et al 2006) or structure-switching signaling aptamers (Wu et al 2011;Yigit et al 2007;Zhang et al 2009). However, in the competition-based approach, the formation of target-functionalized MNPs via a covalent bond is not always viable because of lack of functional groups within such small molecules, and the binding affinities of aptamers in the structure-switching approach are frequently reduced by competition, blocking (Nutiu and Li 2003) and allosteric inhibition (Ricci et al 2012) effects, thus lowering the detection sensitivity.…”

Isolation of RNA Aptamers Targeting HER-2-overexpressing Breast Cancer Cells Using Cell-SELEX

“…11 Aptamers can decorate the surface of magnetic nanoparticles used for magnetic resonance imaging (MRI), to enhance the specificity of imaging. 12 As a cancer therapeutics, aptamers can either directly inhibit the cancer growth signaling pathway by blocking growth factor or growth factor receptors, 13 or be used as "escort aptamers" 11 to deliver therapeutic molecules such as cytotoxic agents, radionuclides, or even small interfering RNAs (siRNAs) to the target cells. Therefore, generation of specific aptamers targeting different cancer cell types and cancer cell surface proteins would greatly aid the development of novel cancer diagnostics and therapeutics.…”