Identification and separation of DNA‐hybridized nanocolloids by Taylor cone harmonics

Abstract

A rapid (minutes) electrospray bead-based DNA hybridization detection technique is developed by spraying a mixture of hybridized and unhybridized silica nanocolloids. With proper far-field control by external electrodes, the trajectory of the ejected nanobeads from the electrospray is governed by specific harmonics of the Laplace equation, which select discrete polar angles along well-separated field maxima near the conducting Taylor cone. Due to Rayleigh fission and evaporation, beads of different size acquire different total charge after ejection and suffer different normal electrophoretic displacement such that they are ejected along well-separated field maxima and are deposited in distinct rings on an intersecting plane. As the hybridized DNA is of the same dimension as that of the nanocolloid, the nanocolloids are hence easily differentiated from the unhybridized ones. This technique is highly specific as the high shear stress in the microjet shears away any non-specifically bound DNA from the nanocolloid surface.

Celebrating singularities: Mathematics and chemical engineering

“…The group and their collaborators have used this unique mathematical feature of the dominant discrete modes near the Taylor cone, including the Taylor mode m = ½, to design a nanocolloid mass spectrometry that can separate nanocolloids of different size. A pending patent is on how such a method can be used to quantify the number of nanocolloids with bound biomolecules, biomarkers that the nanocolloids have captured with specific probes functionalized onto them …”

A Broadly Applicable Assay for Rapidly and Accurately Quantifying DNA Surface Coverage on Diverse Particles

“…2–6 Different conjugation chemistries have been used to immobilize DNA strands onto various particle substrates, including metallic nanoparticles, semiconductive quantum dots (QDs), inorganic upconversion nanoparticles (UCNPs), silica microspheres, and magnetic beads. 7–15 In particular, alkanethiol adsorption has been employed for attaching thiolated DNA onto gold nanoparticles (AuNPs). 7,16 The lanthanide–phosphate interaction has been used to conjugate unmodified DNAs onto lanthanide-doped hydrophobic UCNPs.…”

“…DNA-modified nano- and microparticles can specifically recognize a variety of targets, including nucleic acids, proteins, peptides, small molecules, and metal ions . Accordingly, such particles have proven extraordinarily useful for bioimaging, bioseparation, diagnostic assays, drug targeting, nanotherapeutics, and nanomaterial assembly. − Different conjugation chemistries have been used to immobilize DNA strands onto various particle substrates, including metallic nanoparticles, semiconductive quantum dots (QDs), inorganic upconversion nanoparticles (UCNPs), silica microspheres, and magnetic beads. − In particular, alkanethiol adsorption has been employed for attaching thiolated DNA onto gold nanoparticles (AuNPs). , The lanthanide–phosphate interaction has been used to conjugate unmodified DNAs onto lanthanide-doped hydrophobic UCNPs . The streptavidin (SA)–biotin interaction is often utilized to attach biotinylated DNA onto SA-coated magnetic beads, , QDs, and UCNPs .…”

“…The streptavidin (SA)–biotin interaction is often utilized to attach biotinylated DNA onto SA-coated magnetic beads, , QDs, and UCNPs . In addition, when analyte detection or sample separation is being performed at elevated temperatures, amino-modified DNA has been covalently conjugated onto carboxylated magnetic , or silica particles. Such covalently bound DNA probes offer greater stability for assays that employ heat-induced dehybridization, , as high temperatures can disrupt SA–biotin interaction …”

“…The eluted biotinylated DNAs can then be fluorescently measured. However, this method is not applicable to other conjugation chemistries, such as covalent linkage of thiolated DNA to aminated particles or of amino-labeled DNA to carboxylated magnetic or silica substrates. ,,, …”