Vanessa Velasco

Bio: Vanessa Velasco is an academic researcher from University of Louisville. The author has contributed to research in topics: Carbon nanotube & Electrokinetic phenomena. The author has an hindex of 8, co-authored 9 publications receiving 216 citations. Previous affiliations of Vanessa Velasco include Brigham and Women's Hospital.

Selection of functional human sperm with higher DNA integrity and fewer reactive oxygen species.

Abstract: Fertilization and reproduction are central to the survival and propagation of a species. Couples who cannot reproduce naturally have to undergo in vitro clinical procedures. An integral part of these clinical procedures includes isolation of healthy sperm from raw semen. Existing sperm sorting methods are not efficient and isolate sperm having high DNA fragmentation and reactive oxygen species (ROS), and suffer from multiple manual steps and variations between operators. Inspired by in vivo natural sperm sorting mechanisms where vaginal mucus becomes less viscous to form microchannels to guide sperm towards egg, a chip is presented that efficiently sorts healthy, motile and morphologically normal sperm without centrifugation. Higher percentage of sorted sperm show significantly lesser ROS and DNA fragmentation than the conventional swim-up method. The presented chip is an easy-to-use high-throughput sperm sorter that provides standardized sperm sorting assay with less reliance on operators's skills, facilitating reliable operational steps.

Toxicology Study of Single-walled Carbon Nanotubes and Reduced Graphene Oxide in Human Sperm.

Abstract: Carbon-based nanomaterials such as single-walled carbon nanotubes and reduced graphene oxide are currently being evaluated for biomedical applications including in vivo drug delivery and tumor imaging. Several reports have studied the toxicity of carbon nanomaterials, but their effects on human male reproduction have not been fully examined. Additionally, it is not clear whether the nanomaterial exposure has any effect on sperm sorting procedures used in clinical settings. Here, we show that the presence of functionalized single walled carbon nanotubes (SWCNT-COOH) and reduced graphene oxide at concentrations of 1–25 μg/mL do not affect sperm viability. However, SWCNT-COOH generate significant reactive superoxide species at a higher concentration (25 μg/mL), while reduced graphene oxide does not initiate reactive species in human sperm. Further, we demonstrate that exposure to these nanomaterials does not hinder the sperm sorting process, and microfluidic sorting systems can select the sperm that show low oxidative stress post-exposure.

Photo-mechanical actuation of carbon nanotubes: mechanisms and applications in micro and nano-devices

Abstract: We review the current state of the art in photomechanical actuation of carbon nanotubes and their composites. The article presents key points in the photomechanical responses of carbon nanotubes and show how orientation, alignment and anisotropic optical properties of carbon nanotubes influence photomechanical actuation. The current state of the field of carbon-nanotube polymer photomechanical actuators is presented. The photomechanical responses of nanotube-polymer systems depend on the structure of the actuator, nanotube alignment, entanglement and the presence of pre-strains in the sample. While the mechanism of photomechanical actuation is not fully understood, we discuss some possible mechanisms that contribute to the overall photomechanical responses of carbon nanotubes and their polymer composites. It is expected that the interplay between elastic, electrostatic, polaronic and thermal interactions give rise to the overall photomechanical responses of carbon nanotubes. We also discuss some insights into how the photo-mechanical responses of the carbon nanotubes and their polymers may be coupled to the band structure of carbon nanotubes. Finally, we review the applications of photomechanical actuation of carbon nanotube in Micro-Electro-Mechanical Systems (MEMS) and nanotechnology.

Micro- and nanotechnology approaches for capturing circulating tumor cells

Abstract: Circulating tumor cells (CTC) are cells that have detached from primary tumors and circulate in the bloodstream where they are carried to other organs, leading to seeding of new tumors and metastases. CTC have been known to exist in the bloodstream for more than a century. With recent progress in the area of micro- and nanotechnology, it has been possible to adopt new approaches in CTC research. Microscale and nanoscale studies can throw some light on the time course of CTC appearance in blood and CTC overexpression profiles for cancer-related markers and galvanize the development of drugs to block metastases. CTC counts could serve as endpoint biomarkers and as prognostic markers for patients with a metastatic disease. This paper reviews some of the recent researches on using micro- and nanotechnology to capture and profile CTC.

Dispersion and functionalization of carbon nanotubes for polymer-based nanocomposites: a review

Abstract: Carbon nanotubes (CNTs) hold the promise of delivering exceptional mechanical properties and multi-functional characteristics. Ever-increasing interest in applying CNTs in many different fields has led to continued efforts to develop dispersion and functionalization techniques. To employ CNTs as effective reinforcement in polymer nanocomposites, proper dispersion and appropriate interfacial adhesion between the CNTs and polymer matrix have to be guaranteed. This paper reviews the current understanding of CNTs and CNT/polymer nanocomposites with two particular topics: (i) the principles and techniques for CNT dispersion and functionalization and (ii) the effects of CNT dispersion and functionalization on the properties of CNT/polymer nanocomposites. The fabrication techniques and potential applications of CNT/polymer nanocomposites are also highlighted.

Engineering cancer microenvironments for in vitro 3-D tumor models

Abstract: The natural microenvironment of tumors is composed of extracellular matrix (ECM), blood vasculature, and supporting stromal cells. The physical characteristics of ECM as well as the cellular components play a vital role in controlling cancer cell proliferation, apoptosis, metabolism, and differentiation. To mimic the tumor microenvironment outside the human body for drug testing, two-dimensional (2-D) and murine tumor models are routinely used. Although these conventional approaches are employed in preclinical studies, they still present challenges. For example, murine tumor models are expensive and difficult to adopt for routine drug screening. On the other hand, 2-D in vitro models are simple to perform, but they do not recapitulate natural tumor microenvironment, because they do not capture important three-dimensional (3-D) cell–cell, cell–matrix signaling pathways, and multi-cellular heterogeneous components of the tumor microenvironment such as stromal and immune cells. The three-dimensional (3-D) in vitro tumor models aim to closely mimic cancer microenvironments and have emerged as an alternative to routinely used methods for drug screening. Herein, we review recent advances in 3-D tumor model generation and highlight directions for future applications in drug testing.

Paper-based analytical devices for clinical diagnosis: recent advances in the fabrication techniques and sensing mechanisms.

Abstract: Introduction: There is a significant interest in developing inexpensive portable biosensing platforms for various applications including disease diagnostics, environmental monitoring, food safety, and water testing at the point-of-care (POC) settings. Current diagnostic assays available in the developed world require sophisticated laboratory infrastructure and expensive reagents. Hence, they are not suitable for resource-constrained settings with limited financial resources, basic health infrastructure, and few trained technicians. Cellulose and flexible transparency paper-based analytical devices have demonstrated enormous potential for developing robust, inexpensive and portable devices for disease diagnostics. These devices offer promising solutions to disease management in resource-constrained settings where the vast majority of the population cannot afford expensive and highly sophisticated treatment options.Areas covered: In this review, the authors describe currently developed cellulose and...