Separation of distinct exosome subpopulations: isolation and characterization approaches and their associated challenges.

Exosomes are nano-sized extracellular vesicles that serve as a communications system between cells and have shown tremendous promise as liquid biopsy biomarkers in diagnostic, prognostic, and even therapeutic use in different human diseases. Due to the natural heterogeneity of exosomes, there is a need to separate exosomes into distinct biophysical and/or biochemical subpopulations to enable full interrogation of exosome biology and function prior to the possibility of clinical translation. Currently, there exists a multitude of different exosome isolation and characterization approaches which can, in limited capacity, separate exosomes based on biophysical and/or biochemical characteristics. While notable reviews in recent years have reviewed these approaches for bulk exosome sorting, we herein present a comprehensive overview of various conventional technologies and modern microfluidic and nanotechnological advancements towards isolation and characterization of exosome subpopulations. The benefits and limitations of these different technologies to improve their use for distinct exosome subpopulations in clinical practices are also discussed. Furthermore, an overview of the most commonly encountered technical and biological challenges for effective separation of exosome subpopulations is presented.

An improved strategy for transferring and adhering thin nanoporous alumina membranes onto conducting transparent electrodes for template assisted electrodeposition of high aspect ratio semiconductor nanowires with increased optical absorption.

This article presents a new method for transferring and enhancing the adhesion of thin nanoporous alumina (NPA) membranes onto non-atomically flat substrates like fluorine-doped tin oxide (FTO) coated glass. The study reports use of glycerol as an additive to reduce the brittleness of the polystyrene filler that was used to fill the pores of the NPA membrane. Additionally, a new reflux-based method is reported here for the complete removal of the polystryrene filler from the porous channels of alumina. The adhesion between an NPA membrane and an underlying electrode was enhanced by electrodepositing a thin (∼40 nm) intermediate layer of the conducting polymer polyaniline (PANI). The PANI layer acts as an efficient electrostatic adhesive between the NPA and the conducting glass electrode and ensures ultra-strong adhesion of the NPA membrane, which can survive the harsh conditions of CdTe nanowire electrodeposition (60 °C temperature and an acidic electrolyte) without delamination for 30 min. The resulting nanowires clearly templated the structure of NPA and displayed free-standing nanowires over a large area with a diameter of around 60 nm, a length of approximately 2.8 µm (aspect ratio ∼47) and an areal density of 5.9 × 1012 nanowires cm-2. Total optical absorption measurement on the free-standing CdTe nanowires exhibited a 45% enhancement over a wavelength range of 350-1400 nm as compared to a CdTe planar thin film of same thickness.

Molecular interaction of quercetin and its derivatives against nucleolin in breast cancer: in-silico and in-vitro study.

Nucleolin, a multifaceted RNA binding domain protein is overexpressed in various cancers leading to dysfunction of several cellular signaling pathways. Quercetin, a distinctive bioactive molecule, along with its derivatives have shown exclusive physio-chemical properties which makes them appealing choices for drug development, yet their role in targeted cancer therapy is limited. Here, the RBD domain structure of Nucleolin was modeled and stabilized by MD simulations for a period of 1000 ns. Molecular docking was performed to determine the binding capability of ligands with the target. To determine the stability of the ligand inside the binding pocket of the protein, MD simulation was performed for a period of 250 ns each for Quercetin-4'-o'-Glucoside, Quercetin_9 and Quercetin complexes. Further, in-vitro studies including cytotoxicity and RT-PCR assays were performed to validate quercetin against Nucleolin. Molecular docking and MD Simulation studies suggested a potential mechanism of interaction of Quercetin-4'-o'-Glucoside, Querectin_9 and Quercetin with Nucleolin with the binding free energy of -63.653, -58.86 and -46.9 kcal/mol, respectively. Moreover, Lys 348 and Glu379 were identified as important amino acids in ligand interaction located at the RRM2 motif of Nucleolin. In-vitro studies showed significant downregulation in Nucleolin expression by 15.18 and 2.51-fold at 48h and 72h respectively in MCF-7 cells with Quercetin (IC50 = 160 µM). Our findings suggested the potential role of specific RRM motifs in interaction with natural compounds targeting Nucleolin. This could be an effective strategy in the identification of potential molecules in targeting Nucleolin which can be further explored for developing targeted therapies for breast cancer.Communicated by Ramaswamy H. Sarma.

Carbon quantum dot-nanocomposite hydrogel as Denovo Nexus in rapid chondrogenesis.

The incapability of cartilage to naturally regenerate and repair chronic muscular injuries urges the development of competent bionic rostrums. There is a need to explore faster strategies for chondrogenic engineering using mesenchymal stem cells (MSCs). Along these lines, rapid chondrocyte differentiation would benefit the transplantation demand affecting osteoarthritis (OA) and rheumatoid arthritis (RA) patients. In this report, a de novo nanocomposite was constructed by integrating biogenic carbon quantum dot (CQD) filler into synthetic hydrogel prepared from dimethylaminoethyl methacrylate (DMAEMA) and acrylic acid (AAc). The dominant structural integrity of synthetic hydrogel along with the chondrogenic differentiation potential of garlic peel derived CQDs led to faster chondrogenesis within 14 days. By means of extensive chemical and morphological characterization techniques, we illustrate that the hydrogel nanocomposite possesses lucrative features to influence rapid chondrogenesis. These results were further corroborated by bright field imaging, Alcian blue staining and Masson trichome staining. Thus, this stratagem of chondrogenic engineering conceptualizes to be a paragon in clinical wound care for the rapid manufacturing of chondrocytes.

Current and future strategies for diagnostic and management of obstructive sleep apnea.

INTRODUCTION: Obstructive sleep apnea (OSA) is a common sleep disorder with multiple comorbidities including hypertension, diabetes, and cardiovascular disorders. Detected based on an overnight sleep study is called polysomnography (PSG); OSA still remains undiagnosed in majority of the population mainly attributed to lack of awareness. To overcome the limitations posed by PSG such as patient discomfort and overnight hospitalization, newer technologies are being explored. In addition, challenges associated with current management of OSA using continuous positive airway pressure (CPAP), etc. presents several pitfalls. AREAS COVERED: Conventional and modern detection/management techniques including PSG, CPAP, smart wearable/pillows, bio-motion sensors, etc., have both pros and cons. To fulfill the limitations in OSA diagnostics, there is an imperative need for new technology for screening of symptomatic and more importantly asymptomatic OSA patients to reduce the risk of several associated life-threatening comorbidities. In this line, molecular marker-based diagnostics have shown great promises. EXPERT OPINION: A detailed overview is presented on the OSA management and diagnostic approaches and recent advances in the molecular screening methods. The potentials of biomarker-based detection and its limitations are also portrayed and a comparison between the standard, current modern approaches, and promising futuristic technologies for OSA diagnostics and management is set forth.ABBREVIATIONS AHI: Apnea hypopnea index; AI: artificial intelligence; CAM: Cell adhesion molecules; CPAP: Continuous Positive Airway Pressure; COVID-19: Coronavirus Disease 2019; CVD: Cardiovascular disease; ELISA: Enzyme linked immunosorbent assay; HSAT: Home sleep apnea testing; IR-UWB: Impulse radio-ultra wideband; MMA: maxillomandibular advancement; PSG: Polysomnography; OSA: Obstructive sleep apnea; SOD: Superoxide dismutase; QD: Quantum dot.

Matrix-free LDI mass spectrometry platform using patterned nanostructured gold thin film.

A novel matrix-free LDI MS platform using a thin film of patterned nanostructured gold, capped with methyl- and carboxy-terminated self-assembled monolayers (SAMs) is presented. Calibration on the matrix-free LDI surface was performed using a peptide standard mixture available for MALDI analysis. MS analysis for limit of detection was performed using angiotensin I peptide. Peptide fragments from standard protein digests of bovine serum albumin, bovine catalase, and bovine lactoperoxidase were used to carry out peptide mass fingerprinting analysis. Sequence coverage of each protein digest and the number of detected peptide fragments were compared with conventional MALDI MS on a standard MALDI plate. Versatility of the nanostructured gold LDI substrate is illustrated by performing MS analysis on a protein digest using different enzymes and by small molecule MS analysis.

Permanent superhydrophilic surface modification in microporous polydimethylsiloxane sponge for multi-functional applications.

Polydimethylsiloxane (PDMS) is one of the most preferred material in microfluidic device/biomedical applications because of its unique properties. However, improvement in surface wettability of PDMS is highly desired for microfluidic and biomedical applications as its surface is inherently hydrophobic in nature that restricts flow of aqueous fluid or adherence of biomolecules onto its surface. In spite of several surface modification techniques, prompt recurrence of hydrophobic properties is quite typical in PDMS. Here, we demonstrate a facile and a permanent conversion of a hydrophobic PDMS sponge onto a superhydrophilic state. PDMS sponge was prepared using an eco-friendly sugar leaching method and modified by an ultra-thin coating of polyacrylic acid (PAA). The resultant PDMS-PAA hybrid sponge was found to have highly stable and sustained superhydrophilic property for more than 18 months with water absorption efficiency as high as 89%. Valuable applications like, portable pressure pump in a microfluidic device and as a bioactive matrix for microbial cell immobilization for biodegradation of distillery industry effluent treatment has been demonstrated using these surface modified PDMS sponges.

Dual desorption electrospray ionization-laser desorption ionization mass spectrometry on a common nanoporous alumina platform for enhanced shotgun proteomic analysis.

A gold coated nanoporous alumina surface was used for dual ionization mode mass spectrometric analysis using desorption electrospray ionization (DESI) and laser desorption ionization (LDI). DESI and LDI mass spectrometry (MS) from the nanoporous alumina surface were compared with conventional electrospray ionization (ESI) mass spectrometry and matrix assisted laser desorption ionization (MALDI) for analysis of tryptic digests of proteins. Combined use of DESI and LDI offer greater peptide coverage than either method alone and comparable peptide coverage as with dual MALDI and ESI. This dual ionization technique using a common platform with same sample spot demonstrates a potential time and cost-effective tool for improved shotgun proteomic analysis.

Rapid Processing of Wafer-Scale Anti-Reflecting 3D Hierarchical Structures on Silicon and Its Templation.

Hierarchically structured silicon (Si) surfaces with a combination of micro/nano-structures are highly explored for their unique surface and optical properties. In this context, we propose a rapid and facile electroless method to realize hierarchical structures on an entire Si wafer of 3″ diameter. The overall process takes only 65 s to complete, unlike any conventional wet chemical approach that often combines a wet anisotropic etching of (100) Si followed by a metal nanoparticle catalyst etching. Hierarchical surface texturing on Si demonstrates a broadband highly reduced reflectance with average R% ~ 2.7% within 300⁻1400 nm wavelength. The as-fabricated hierarchical structured Si was also templated on a thin transparent layer of Polydimethylsiloxane (PDMS) that further demonstrated prospects for improved solar encapsulation with high optical clarity and low reflectance (90% and 2.8%).

Influence of spinel substrate and over-layer for enhanced SAW and AO properties with KNbO3 thin film.

Surface acoustic wave (SAW) propagation characteristics have been studied using modeling calculations for a potassium niobate (KNbO3) thin film-layered structure with (001) and (110) orientation on a single crystal spinel (MgAl2O4) substrate, and a spinel buffer layer on silicon. Variation in the electromechanical coupling and acoustic attenuation has been compared. A significantly high value of coupling factor (k2max = 23%) is obtained for the (001)KNbO3/spinel structure by introducing an optimum thickness of spinel over-layer for potential wide bandwidth SAW device applications. The dispersion characteristics with the (110) KNbO3 orientation indicate an initial peak in the coupling coefficient value (k2max = 8.8%) at a relatively low KNbO3 film thickness that appears attractive for fabricating devices with thinner films. The KNbO3 film with (001) orientation is found attractive for efficient acousto-optic (AO) device application with the formation of a symmetric waveguide structure (spinel(0.5 microm)/KNbO3(1.0 microm)/spinel). A high value of k2 = 23.5% with 50% diffraction efficiency has been obtained for the spinel(0.5 microm)/KNbO3(1.0 microm)/spinel structure at 1 GHz SAW frequency and 633 nm optical wavelength at a very low input drive power of 15.4 mW.

Effects of thin-film structural parameters on laser desorption/ionization from porous alumina.

Nanoporous aluminum oxide layers, grown by anodization of aluminum thin films on glass and then sputter-coated with gold, were used to study the effects of the thin-film structural parameters on laser desorption/ionization (LDI) mass spectrometry (MS) of peptides. Variation of MS signal intensity was examined as a function of alumina pore depth, pore width, and gold layer thickness. Peptide molecular ion intensity was optimal with porous alumina formed from aluminum films of approximately 600-nm thickness; thinner or thicker films gave significantly lower signals. Signals decreased when pore sizes were increased beyond the as-formed width of approximately 100 nm. The MS signal also varied with the thickness of the sputtered gold layer with an optimum thickness being approximately 90 nm. The results of these studies provide values for empirical optimization of LDI MS performance as well as potential clues to the LDI mechanism.

Monolithic media in microfluidic devices for proteomics.

Considerable effort has been invested in the development of integrated microfluidic devices for fast and highly efficient proteomic studies. Among various fabrication techniques for the preparation of analytical components (separation columns, reactors, extractors, valves, etc.) in integrated microchips, in situ fabrication of monolithic media is receiving increasing attention. This is mainly due to the ease and simplicity of preparation of monolithic media and the availability of various precursors and chemistries. In addition, UV-initiated photopolymerization technique enables the incorporation of multiple analytical components into specified parts of a single microchip using photomasks. This review summarizes preparation methods for monolithic media and their application as microfluidic analytical components in microchips.

Tissue chips as headway model and incitement technology.

Tissue on a chip or organ-on-chip (OOC) is a technology that's dignified to form a transformation in drug discovery through the use of advanced platforms. These are 3D in-vitro cell culture models that mimic micro-environment of human organs or tissues on artificial microstructures built on a portable microfluidic chip without involving sacrificial humans or animals. This review article aims to offer readers a thorough and insightful understanding of technology. It begins with an in-depth understanding of chip design and instrumentation, underlining its pivotal role and the imperative need for its development in the modern scientific landscape. The review article explores into the myriad applications of OOC technology, showcasing its transformative impact on fields such as radiobiology, drug discovery and screening, and its pioneering use in space research. In addition to highlighting these diverse applications, the article provides a critical analysis of the current challenges that OOC technology faces. It examines both the biological and technical limitations that hinder its progress and efficacy and discusses the potential advancements and innovations that could drive the OOC technology forward. Through this comprehensive review, readers will gain a deep appreciation of the significance, capabilities, and evolving landscape of OOC technology.