Designer tetrahedral DNA framework-based microfluidic technology for multivalent capture and release of circulating tumor cells

Renewable and Switchable Biofunctional Modification of Poly(dimethylsiloxane) Surfaces via Host-Guest Interactions for Enhanced Capture of Circulating Tumor Cells in Microfluidics

Circulating tumor cells (CTCs) are crucial for understanding cancer metastasis. Poly(dimethylsiloxane) (PDMS) microfluidic chips utilizing aptamers (APTs) effectively separate CTCs, but the hydrophobicity of PDMS causes issues with nonspecific adsorption and reduces cell viability. Therefore, it is imperative to develop innovative surface modification techniques for PDMS to enhance its biocompatibility and optimize its performance in microfluidic applications. In this study, oligo(ethylene glycol) methacrylate (OEGMA) and adamantane-modified OEGMA were copolymerized onto an initiator-containing PDMS surface. Poly(OEGMA) prevents nonspecific adsorption, and biotin-modified β-cyclodextrin (β-CD) was introduced through host-guest interaction between β-CD and adamantane. By using the biotin-streptavidin interaction, streptavidin and biotin-modified aptamers (TD05 APT and Sgc8 APT) were sequentially immobilized on the copolymer-grafted PDMS substrate. The data indicate that the PDMS substrate functionalized with TD05 APT achieved a capture efficiency of 91% and a selectivity of 30.2 for Ramos cells, while the substrate functionalized with Sgc8 APT achieved a capture efficiency of 93% and a selectivity of 33.3 for CEM cells. Furthermore, treating the APT-functionalized surfaces with sodium dodecyl sulfate released the β-CD component, allowing for the regeneration and switching of the surface biofunctionality by reimmobilizing TD05 APT or Sgc8 APT. Finally, the PDMS microfluidic chips modified using this strategy achieved high capture efficiency (96% for Ramos cells, 93% for CEM cells) and high selectivity (11.4 for Ramos cells, 9.2 for CEM cells). The host-guest chemistry endows the modified PDMS substrate with renewable and switchable biofunctionality, offering insights into the potential applications in the isolation and enrichment of CTCs.

Aptamer-based microfluidics for the detection of cancer biomarkers

Early diagnosis of cancer is a major concern in clinical medicine. Recently, aptamer-based microfluidics have offered promising platforms for the sensitive detection of cancer biomarkers. This review summarizes the application of aptamer sensors in the microfluidic platform for cancer biomarker analysis. The materials for microfluidic aptamer biosensor fabrication, unique design based on microposts, materials for enhanced detection capability, and the application principle of combining with other detection methods are introduced in detail, so as to demonstrate its development potential in cancer diagnosis and personalized therapy. Finally, the challenges and opportunities for developing miniaturized diagnostic platforms are discussed.

Capture and lyase-triggered release of circulating tumor cells using a disposable microfluidic chip embedded with core/shell nylon-6/Ca(II)-alginate immunofiber mats

High-efficiency capture, release, and reculture of circulating tumor cells (CTCs) can significantly advance individualized cancer treatments. To achieve efficient CTC release without compromising their viability for subsequent reculture, an effective CTC capture/release system was developed. Nylon-6 (N6) and a cross-linked alginate hydrogel with Ca(II) were used as the shell and core, respectively, to prepare N6/Ca-Alg immunofiber mats using coaxial electrospinning. A 3 wt% concentration of Ca(II) was used to increase the viscosity of the alginate solution and generate a degradable coating on the N6 fiber. After modification with streptavidin and anti-EpCAM, the N6/Ca-Alg immunofiber mat was embedded within a disposable microfluidic chip to investigate the capture capacity of CTCs. The maximum adsorption capacity of CTCs was approximately 34 cells per mm2, while the viability of the captured cells was 95.1% after being released from the fibrous mats. The outer Ca-alginate hydrogel coating effectively enhanced the viability of the released cells for reculture. In spiked blood samples, our microfluidic system was able to specifically identify DLD1 cells from 10 mL of human whole blood at a concentration of 65.6 cells per mL with 67.9% efficiency within 30 minutes. Under the flow of alginate lyase solution at 0.4 mg mL-1, the reculture efficiency of the released cells after 7 days reached 274.5%. Our proposed method provides an ideal fibrous mat to be embedded within a microfluidic chip for capturing and releasing CTCs for precision medicine applications, using recultured CTCs in individualized anti-tumor therapies.

Aptamer selection via versatile microfluidic platforms and their diverse applications

Aptamers are synthetic oligonucleotides that bind with high affinity and specificity to various targets, making them invaluable for diagnostics, therapeutics, and biosensing. Microfluidic platforms can improve the efficiency and scalability of aptamer selection, especially through advancements in systematic evolution of ligands by exponential enrichment (SELEX) methods. Microfluidic SELEX methods are less time-consuming and labor-intensive and include critical steps like library preparation, binding, partitioning, and amplification. This review examines the contributions of microfluidic technology to SELEX-based aptamer identification, with alternative methods like conditional SELEX, in vivo-like SELEX and Non-SELEX for selecting aptamers and also discusses critical SELEX steps over the past decade. This work also examined the integrated microfluidic systems for SELEX, highlighting innovations such as conditional SELEX and in vivo-like SELEX. These advancements provide potential solutions to existing challenges in aptamer selection using conventional SELEX, especially concerning biological samples. A trend toward non-SELEX methods was also reviewed and discussed, wherein nucleic acid amplification was eliminated to improve aptamer selection. Microfluidic platforms have demonstrated versatility not only in aptamer selection but also in various detection applications; they allow for precise control of liquid flow and have been essential in the advancement of therapeutic aptamers, facilitating accurate screening, enhancing drug delivery systems, and enabling targeted therapeutic interventions. Although advances in microfluidic technology are expected to enhance aptamer-based diagnostics, therapeutics, and biosensing, challenges still persist, especially in up-scaling microfluidic systems for various clinical applications. The advantages and limitations of integrating microfluidic platforms with aptamer development are further addressed, emphasizing areas for future research. We also present a perspective on the future of microfluidic systems and aptamer technologies, highlighting their increasing significance in healthcare and diagnostics.

Ultra-sensitive fluorescence-activated droplet single-cell sorting based on Tetramer-HCR-EvaGreen amplification

The current single-cell analysis technologies such as fluorescence-activated cell sorting (FACS) and fluorescence-activated droplet sorting (FADS) could decipher the cellular heterogeneity but were constrained by low sorting performance and cell viability. Here, an ultra-sensitive single-cell sorting platform has been developed by integrating the FADS technology with Tetramer-HCR-EvaGreen (THE) fluorescence signal amplification. The THE system produced much higher fluorescence signal than that of the single Tetramer or Tetramer-HCR signal amplification. Upon application to target MCF-7 cells, the platform exhibited high efficacy and selectivity while maintaining more than 95% cell viability. The THE-FADS achieved sorting efficiencies of 55.5% and 50.3% with purities of 91% and 85% for MCF-7 cells in PBS solutions and simulated serum samples, respectively. The sorted MCF-7 cells showed similar proliferation together with CK19 and EGFR mRNA expression compared with the control cells. The established THE-FADS showed the promising prospects to cellular heterogeneity understanding and personalized medicine.

Circulating Tumour Cells, Cell Free DNA and Tumour-Educated Platelets as Reliable Prognostic and Management Biomarkers for the Liquid Biopsy in Multiple Myeloma

Simple Summary

Even though the presently employed biomarkers in the detection and management of multiple myeloma are demonstrating encouraging results, the mortality percentage of the malignancy is still elevated. Thus, searching for new diagnostic or prognostic markers is pivotal. Liquid biopsy allows the examination of circulating tumour DNA, cell-free DNA, extracellular RNA, and cell free proteins, which are released into the bloodstream due to the breakdown of tumour cells or exosome delivery. Liquid biopsy can now be applied in clinical practice to diagnose, and monitor multiple myeloma, probably allowing a personalized treatment of the disease.

Abstract

Liquid biopsy is one of the fastest emerging fields in cancer evaluation. Circulating tumour cells and tumour-originated DNA in plasma have become the new targets for their possible employ in tumour diagnosis, and liquid biopsy can define tumour burden without invasive procedures. Multiple Myeloma, one of the most frequent hematologic tumors, has been the target of therapeutic progresses in the last few years. Bone marrow aspirate is the traditional tool for diagnosis, prognosis, and genetic evaluation in multiple myeloma patients. However, this painful procedure presents a relevant drawback for regular disease examination as it requires an invasive practice. Moreover, new data demonstrated that a sole bone marrow aspirate is incapable of expressing the multifaceted multiple myeloma genetic heterogeneity. In this review, we report the emerging usefulness of the assessment of circulating tumour cells, cell-free DNA, extracellular RNA, cell-free proteins, extracellular vesicles, and tumour-educated platelets to evaluate the changing mutational profile of multiple myeloma, as early markers of disease, reliable predictors of prognosis, and as useful tools to perform less invasive monitoring in multiple myeloma.