Low level epifluorescent detection of nanoparticles and DNA on dielectrophoretic microarrays

Emerging on-chip electrokinetic based technologies for purification of circulating cancer biomarkers towards liquid biopsy: A review

Early detection of cancer can significantly reduce mortality and save lives. However, the current cancer diagnosis is highly dependent on costly, complex, and invasive procedures. Thus, a great deal of effort has been devoted to exploring new technologies based on liquid biopsy. Since liquid biopsy relies on detection of circulating biomarkers from biofluids, it is critical to isolate highly purified cancer-related biomarkers, including circulating tumor cells (CTCs), cell-free nucleic acids (cell-free DNA and cell-free RNA), small extracellular vesicles (exosomes), and proteins. The current clinical purification techniques are facing a number of drawbacks including low purity, long processing time, high cost, and difficulties in standardization. Here, we review a promising solution, on-chip electrokinetic-based methods, that have the advantage of small sample volume requirement, minimal damage to the biomarkers, rapid, and label-free criteria. We have also discussed the existing challenges of current on-chip electrokinetic technologies and suggested potential solutions that may be worthy of future studies.

Molecular Rotors for Universal Quantitation of Nanoscale Hydrophobic Interfaces in Microplate Format

Hydrophobic self-assembly pairs diverse chemical precursors and simple formulation processes to access a vast array of functional colloids. Exploration of this design space, however, is stymied by lack of broadly general, high-throughput colloid characterization tools. Here, we show that a narrow structural subset of fluorescent, zwitterionic molecular rotors, dialkylaminostilbazolium sulfonates [DASS] with intermediate-length alkyl tails, fills this major analytical void by quantitatively sensing hydrophobic interfaces in microplate format. DASS dyes supersede existing interfacial probes by avoiding off-target fluorogenic interactions and dye aggregation while preserving hydrophobic partitioning strength. To illustrate the generality of this approach, we demonstrate (i) a microplate-based technique for measuring mass concentration of small (20-200 nm), dilute (submicrogram sensitivity) drug delivery nanoparticles; (ii) elimination of particle size, surfactant chemistry, and throughput constraints on quantifying the complex surfactant/metal oxide adsorption isotherms critical for environmental remediation and enhanced oil recovery; and (iii) more reliable self-assembly onset quantitation for chemically and structurally distinct amphiphiles. These methods could streamline the development of nanotechnologies for a broad range of applications.

DNA dielectrophoresis: Theory and applications a review

Dielectrophoresis is the migration of an electrically polarizable particle in an inhomogeneous electric field. This migration can be exploited for several applications with (bio)molecules or cells. Dielectrophoresis is a noninvasive technique; therefore, it is very convenient for (selective) manipulation of (bio)molecules or cells. In this review, we will focus on DNA dielectrophoresis as this technique offers several advantages in trapping and immobilization, separation and purification, and analysis of DNA molecules. We present and discuss the underlying theory of the most important forces that have to be considered for applications with dielectrophoresis. Moreover, a review of DNA dielectrophoresis applications is provided to present the state-of-the-art and to offer the reader a perspective of the advances and current limitations of DNA dielectrophoresis.

Isolation and enrichment of circulating biomarkers for cancer screening, detection, and diagnostics

Much research has been performed over the past several decades in an attempt to conquer cancer. Tissue biopsy is the conventional method for gathering biological materials to analyze cancer and has contributed greatly to the understanding of cancer. However, this method is limited because it is time-consuming (requires tissue sectioning, staining, and pathological analysis), costly, provides scarce starting materials for multiple tests, and is painful. A liquid biopsy, which analyzes cancer-derived materials from various body fluids using a minimally invasive procedure, is more practical for real-time monitoring of disease progression than tissue biopsy. Biomarkers analyzable through liquid biopsy include circulating tumor cells (CTCs), exosomes, circulating cell-free DNA (cfDNA), miRNA, and proteins. Research on CTCs has been actively conducted because CTCs provide information on the whole cell, unlike the other biomarkers mentioned above. However, owing to the rarity and heterogeneity of CTCs, CTC research faces many critical concerns. Although exosomes and cfDNA have some technical challenges, they are being highlighted as new target materials. That is because they also have genetic information on cancers. Even though the number of exosomes and cfDNA from early stage cancer patients are similar to healthy individuals, they are present in high concentrations after metastasis. In this article, we review several technologies for material analyses of cancer, discuss the critical concerns based on hands-on experience, and describe future directions for cancer screening, detection, and diagnostics.

Modern trends in biophotonics for clinical diagnosis and therapy to solve unmet clinical needs

This contribution covers recent original research papers in the biophotonics field. The content is organized into main techniques such as multiphoton microscopy, Raman spectroscopy, infrared spectroscopy, optical coherence tomography and photoacoustic tomography, and their applications in the context of fluid, cell, tissue and skin diagnostics. Special attention is paid to vascular and blood flow diagnostics, photothermal and photodynamic therapy, tissue therapy, cell characterization, and biosensors for biomarker detection.

Dielectrophoretic recovery of DNA from plasma for the identification of chronic lymphocytic leukemia point mutations

Aim

Circulating cell free (ccf) DNA contains information about mutations affecting chronic lymphocytic leukemia (CLL). The complexity of isolating DNA from plasma inhibits the development of point-of-care diagnostics. Here, we introduce an electrokinetic method that enables rapid recovery of DNA from plasma.

Materials & methods

ccf-DNA was isolated from 25 µl of CLL plasma using dielectrophoresis. The DNA was used for PCR amplification, sequencing and analysis.

Results

The ccf-DNA collected from plasma of 5 CLL patients revealed identical mutations to those previously identified by extracting DNA from CLL cells from the same patients.

Conclusion

Rapid dielectrophoresis isolation of ccf-DNA directly from plasma provides sufficient amounts of DNA to use for identification of point mutations in genes associated with CLL progression.

Recovery of Drug Delivery Nanoparticles from Human Plasma Using an Electrokinetic Platform Technology

The effect of complex biological fluids on the surface and structure of nanoparticles is a rapidly expanding field of study. One of the challenges holding back this research is the difficulty of recovering therapeutic nanoparticles from biological samples due to their small size, low density, and stealth surface coatings. Here, the first demonstration of the recovery and analysis of drug delivery nanoparticles from undiluted human plasma samples through the use of a new electrokinetic platform technology is presented. The particles are recovered from plasma through a dielectrophoresis separation force that is created by innate differences in the dielectric properties between the unaltered nanoparticles and the surrounding plasma. It is shown that this can be applied to a wide range of drug delivery nanoparticles of different morphologies and materials, including low-density nanoliposomes. These recovered particles can then be analyzed using different methods including scanning electron microscopy to monitor surface and structural changes that result from plasma exposure. This new recovery technique can be broadly applied to the recovery of nanoparticles from high conductance fluids in a wide range of applications.