Recent Trends and Innovations in Bead-Based Biosensors for Cancer Detection.

Demand is strong for sensitive, reliable, and cost-effective diagnostic tools for cancer detection. Accordingly, bead-based biosensors have emerged in recent years as promising diagnostic platforms based on wide-ranging cancer biomarkers owing to the versatility, high sensitivity, and flexibility to perform the multiplexing of beads. This comprehensive review highlights recent trends and innovations in the development of bead-based biosensors for cancer-biomarker detection. We introduce various types of bead-based biosensors such as optical, electrochemical, and magnetic biosensors, along with their respective advantages and limitations. Moreover, the review summarizes the latest advancements, including fabrication techniques, signal-amplification strategies, and integration with microfluidics and nanotechnology. Additionally, the challenges and future perspectives in the field of bead-based biosensors for cancer-biomarker detection are discussed. Understanding these innovations in bead-based biosensors can greatly contribute to improvements in cancer diagnostics, thereby facilitating early detection and personalized treatments.

Rapid and Sensitive Nano-Immunosensors for Botulinum.

Botulinum is a deadly bacterial toxin that causes neuroparalytic disease. However, appropriate tools to detect trace toxic proteins are scarce. This study presents a bead-based diffusometric technique for the rapid, simple, and quantitative detection of biological toxins. Functionalized particles called nano-immunosensors were fabricated by forming sandwiched immunocomplexes comprising Au nanoparticles (AuNPs), toxic proteins, and antibodies on fluorescent probe particles. Particle diffusivity tended to decline with increasing concentration of the target proteins. Calibration curves of purified botulinum toxins (0.01-500 ng/mL) were obtained from whole milk and bovine serum, and results suggested that measurement was independent of the background matrix. The activity of botulinum toxin was evaluated by coating synaptosomal-associated protein 25 (SNAP-25) on fluorescent probe particles. AuNP-conjugated antibodies attached to the probe particles when SNAP-25 proteins were cleaved by active botulinum. Thus, toxicity could be detected from slight changes in diffusivity. A short measurement time of 2 min and a limit of detection of 10 pg/mL were achieved. The nano-immunosensors demonstrated rapid biosensing capability and met the demands of onsite screening for food safety, medical instrument hygiene, and cosmetic surgery products.

The chondroitin sulfate moiety mediates thrombomodulin-enhanced adhesion and migration of vascular smooth muscle cells.

BACKGROUND: Thrombomodulin (TM), a transmembrane glycoprotein highly expressed in endothelial cells (ECs), is a potent anticoagulant maintaining circulation homeostasis. Under inflammatory states, TM expression is drastically reduced in ECs while vascular smooth muscle cells (VSMCs) show a robust expression of TM. The functional role of TM in VSMCs remains elusive. METHODS: We examined the role of TM in VSMCs activities in human aortic VSMCs stimulated with platelet-derived growth factor-BB (PDGF-BB). Using rat embryonic aorta-derived A7r5 VSMCs which do not express TM, the role of the chondroitin sulfate (CS) moiety of TM in VSMCs was delineated with cells expressing wild-type TM and the CS-devoid TM mutant. RESULTS: Expression of TM enhanced cell migration and adhesion/spreading onto type I collagen, but had no effect on cell proliferation. Knocking down TM with short hairpin RNA reduced PDGF-stimulated adhesion and migration of human aortic VSMCs. In A7r5 cells, TM-mediated cell adhesion was eradicated by pretreatment with chondroitinase ABC which degrades CS moiety. Furthermore, the TM mutant (TMS490, 492A) devoid of CS moiety failed to increase cell adhesion, spreading or migration. Wild-type TM, but not TMS490, 492A, increased focal adhesion kinase (FAK) activation during cell adhesion, and TM-enhanced cell migration was abolished by a function-blocking anti-integrin ß1 antibody. CONCLUSION: Chondroitin sulfate modification is required for TM-mediated activation of ß1-integrin and FAK, thereby enhancing adhesion and migration activity of VSMCs.

Enhanced diffusometric immunosensing with grafted gold nanoparticles for detection of diabetic retinopathy biomarker tumor necrosis factor-α.

Diffusometry is sensitive to geometric changes of particles. Target antigens can be detected through diffusivity changes resulting from their immunoreactions by functionalizing particle surface with a specific antibody. Considering that Brownian motion is a self-driven phenomenon, diffusometric immunosensing features several characteristics, such as no-washing steps, rapid detection, high flexibility, and high sensitivity. Until recently, this technique has been applied to many biomedical fields, such as monitoring of microorganism motility and diagnosis of diseases with biomarkers. Despite the abovementioned advantages, diffusivity changes in conventional diffusometry can be compromised at low-abundance antigens because proteins are much smaller than capture particles. To overcome such restriction, we present an improved diffusometric immunosensing technique by grafting additional gold nanoparticles (AuNPs) to capture particles to enhance size changes. A diabetic retinopathy (DR) biomarker, tumor necrosis factor-α was selected to evaluate the proposed immunosensing technique. Spherical AuNPs showed better enhancement than rod-like AuNPs during measurement. Limit of detection was improved by at least 100-fold down to 10pg/mL. A dichotomous method was also developed to enable rapid detection and avoid tedious calibration. The relationship of concentrations between the two solutions used can be explicitly determined by comparing diffusivity of an unknown concentration of target molecules with that of a reference solution. Minimum discernible concentration reached as low as twofold higher or lower than basal concentration. Tear samples were collected from four volunteers, including three healthy subjects and one proliferative DR patient to prove the concept in diagnosis of the disease. All data showed good agreement with preset conditions. The technique eventually provides an insight into rapid diagnoses of diseases in the early stage.

Reactive oxygen species derived from NADPH oxidase 1 and mitochondria mediate angiotensin II-induced smooth muscle cell senescence.

Cellular senescence has emerged as an important player in both physiology and pathology. Excessive reactive oxygen species (ROS) is known to mediate cellular senescence. NADPH oxidases are major sources for ROS production in the vascular wall; the roles of different NADPH oxidase isoforms in cellular senescence remain unclear, however. We investigated the roles of two NADPH oxidase isoforms in mitochondrial dysfunction during angiotensin II (Ang II)-induced cellular senescence of human aortic vascular smooth muscle cells (VSMCs). Ang II (10(-7)M) stimulated ROS generation, exhibiting early increases between 30 and 60min and sustained increases between 24h and 72h, and induced VSMCs senescence after 48h or 72h treatment as assessed with senescence-associated ß-galactosidase activity and the expression of two cell cycle inhibitors, p21 and p16. ROS scavengers and membrane-permeable catalase (catalase-PEG) reduced Ang II-stimulated cellular senescence. Furthermore, small interfering RNA (siRNA) of NADPH oxidase catalytic subunit Nox1, but not that of another isoform Nox4, inhibited Ang II-induced cellular senescence. Nox1 siRNA inhibited both early and sustained ROS increases induced by Ang II. In addition, a mitochondrial-specific antioxidant, mitoQ10, effectively inhibited Ang II-induced ROS increases and cellular senescence. Ang II decreased ATP synthesis and induced mitochondrial membrane depolarization, which were attenuated by pre-treating cells with Nox1 siRNA, mitoQ10 or catalase-PEG. The effect of Ang II on the mitochondrial regulator peroxisome-proliferator-activated receptor gamma coactivator-1α (PGC-1α) and its downstream genes was examined. Ang II stimulated S570 phosphorylation of PGC-1α with concomitant decreases in catalase and uncoupling protein-2 (UCP-2) levels between 12h and 72h, which were inhibited by Nox1 siRNA. Knockdown of both catalase and UCP-2 mimicked Ang II-induced VSMC senescence. These results suggested that Ang II-stimulated Nox1 activation mediates mitochondrial dysfunction, probably by decreasing PGC-1α activity and increasing mitochondrial oxidative stress, and leads to cellular senescence of VSMCs.

ROS-mediated downregulation of MYPT1 in smooth muscle cells: a potential mechanism for the aberrant contractility in atherosclerosis.

Reactive oxygen species (ROS) mediates the aberrant contractility in hypertension. Abnormal contractility occurs in atherosclerotic vessels but changes in proteins that regulate contractility remain poorly understood. Myosin phosphatase (MP) activity, which regulates smooth muscle relaxation, is regulated by the phosphorylation of its regulatory subunit, MP targeting subunit 1 (MYPT1). In the present study, we examined the roles of ROS in MP subunit expression both in cultured human aortic smooth muscle cells (HASMCs) and during atherosclerosis progression in apolipoprotein E-knockout (apoE-KO) mice. Furthermore, the effect of decreased MYPT1 on actin cytoskeleton and cell migration activity was assessed in HASMCs. Short hairpin RNA-mediated knockdown of MYPT1 increased stress fibers and attenuated platelet-derived growth factor-induced cell migration in HASMCs. Superoxide anion-inducing agent LY83583 downregulated MYPT1 mRNA and protein levels, but did not affect the phosphorylation of MYPT1 and catalytic subunit of MP, PP1δ. The LY83583-induced decrease in MYPT1 was abolished by co-treating with superoxide dismutase or by inhibiting NADPH oxidase with diphenyleneiodonium. Treatment of peroxynitrite, but not hydrogen peroxide (H2O2), downregulated MYPT1 protein expression and induced MYPT1 phosphorylation without affecting mRNA levels. Co-treatment with a proteasome inhibitor, MG-132, eliminated peroxynitrite-induced MYPT1 downregulation. In apoE-KO mice, MYPT1 protein, but not mRNA, levels were markedly decreased in 16-week- and 24-week-old mice. Oral estrogen treatment, which was previously shown to decrease aortic ROS levels, upregulated aortic MYPT1 expression. Moreover, reduction in MYPT1 expression correlated with increased aortic sensitivity toward vasoconstrictors. These results suggested that during atherosclerosis progression oxidative stress mediates the downregulation of MYPT1, which may inhibit smooth muscle cell migration and contribute to the aberrant contractility.

Decolorization of reactive dye using a photo-ferrioxalate system with brick grain-supported iron oxide.

The photocatalytic activity of a brick grain-supported iron oxide (denoted as B1) was tested for its activity to degrade Reactive Black 5 (RB5) in the presence of oxalic acid. B1 was obtained as a solid waste from a wastewater treatment plant, and characterized using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray powder diffraction (XRD) and N(2) adsorption/desorption isotherm analyses. The decolorization experiments were performed in a fluidized bed reactor with aeration under UV-A irradiation (λ = 365 nm). The effects of various factors such as solution pH, concentration of oxalic acid and dissolved oxygen on the decolorization of RB5 were evaluated considering the contributions of adsorption and photo-catalytic degradation. The role of dissolved iron in the removal of RB5 and the stability of B1 were also examined. In addition, the removal of TOC during the photo-catalytic reaction was monitored.

Thermodynamics and kinetics of adsorption of Cu(II) onto waste iron oxide.

This study investigates low-cost sorbents as replacements for current costly methods of removing heavy metals from solution. This investigation explores the waste iron oxide material (F1), which is a by-product of the fluidized-bed reactor (FBR)-Fenton reaction, for use in the treatment of the wastewater in Taiwan. X-ray powder diffraction (XRD) and scanning electron microscopy (SEM) were used to characterize the F1. In this investigation, F1 are tested as adsorbents for removing copper (Cu(2+)) from aqueous solutions. The highest Cu(2+) adsorption capacity of F1 adsorbent was determined as 0.21 mmolg(-1) for 0.8 mmoldm(-3) initial Cu(2+) concentration at pH 6.0 and 300 K. Adsorption data were well described by the Freundlich model and the thermodynamic constants of the adsorption process, DeltaG degrees , DeltaH degrees and DeltaS degrees were evaluated as -6.12 kJmol(-1) (at 318 K), 9.2 kJmol(-1) and 48.19 Jmol(-1)K(-1) (at 318 K), respectively. Additionally, a pseudo-second-order rate model was adopted to describe the kinetics of adsorption.