Xudong Cao

Xudong Cao
University of Ottawa · Department of Chemical and Biological Engineering

About

87
Publications
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Publications

Publications (87)
Article
Full-text available
Aptamers are short and single-stranded DNA or RNA molecules with highly programmable structures that give them the ability to interact specifically with a large variety of targets, including proteins, cells, and small molecules. Multivalent aptamers refer to molecular constructs that combine two or more identical or different types of aptamers. Mul...
Chapter
Full-text available
Lab-on-a-chip (LOC) devices are gaining significant attentions in fast-response analytical fields due to their demonstrated advantages in portability, sensitivity, sample size, and detection time. In this chapter, we aim to review the most recent developments of LOC in detections. To achieve this, we first review materials that are commonly used to...
Article
An authenticity-based method was developed to detect economically motivated adulteration (EMA) in milk. To achieve this goal, 46 peptides released from trypsin digested milk proteins were identified and marker peptides were further selected based on their digestibility and stability characteristics to allow further quantifications of the milk prote...
Article
We investigated the application of rolling circle amplification (RCA) to modify microfluidic channels for potential sensitive detection applications. To this end, a novel in situ capturing RCA (cRCA) strategy was used to modify the inner surfaces of microfluidic channels with cRCA products that featured repeating tandem capturing aptamers specific...
Article
Contamination of food by bacterial pathogens is one of the biggest concerns in the food industry as it can result in serious human illnesses and death. Approaches to eliminate bacteria from outer surfaces of food products would be an effective way to safeguard against bacterial contamination. Nanopillars found on natural surfaces have been shown to...
Article
Aptamer based microfluidic platforms have been developed rapidly in recent years, and strategies to improve detection sensitivities of such platforms have attracted a significant amount of attention. To achieve whole cell sensitive detections by microfluidic devices, a new dual-rolling circle amplification (RCA) detection approach is presented in t...
Article
Decompressive craniectomy (DC) is a standard surgical procedure performed on stroke patients in which a portion of a skull is removed and a duraplasty membrane is applied onto the brain. While DC can significantly reduce the risk of death, it does not reverse the stroke damage. In this study, a novel biosynthesized cellulose (BC)-based drug releasi...
Article
Spinal cord injury (SCI) is a central nervous disorder that can result in permanent motor and sensory damage due to a severed communication pathway. Although there is currently no effective treatment, nerve guide tubes have been used to bridge the injured stumps and act as drug delivery systems. In this study, BC nerve guides were prepared, and ner...
Chapter
Nano-engineering materials-based diagnosis and treatment of central nervous systems (CNS) ailments has significantly advanced with our deepened knowledge of the pathophysiology of the blood–brain barrier. Unlike other nanoparticle-based tissue engineering strategies, the use of nanoparticles in the CNS must be specifically engineered to circumvent...
Article
The cover image is based on the Original Article Rolling circle amplification and its application in microfluidic systems for E. coli O157:H7 detections by Xudong Cao, Yuqian Jiang, Zhenyu Qiu et al., https://doi.org/10.1111/jfs.12671
Article
Rolling circle amplification (RCA) has been widely used to enhance detection signals as its long single‐stranded RCA products can provide multiple binding sites for signal probes for sensitive detections. In the current study, we employ atomic force microscopy (AFM) to monitor the RCA products during the course of the RCA process over time. Subsequ...
Article
Full-text available
Aptamers have been widely used to recognize and capture their targets in sensitive detection applications, such as in detections of circulating tumor cells. In this study, we investigate the effects of different lengths of oligo-T spacers on surface tethered sgc8 aptamers and their target capturing performances. To achieve this, sgc8 aptamers were...
Article
Full-text available
Development of biomaterials for the diagnosis and treatment of neurotraumatic ailments has been significantly advanced with our deepened knowledge of the pathophysiology of neurotrauma. Canadian research in the fields of biomaterial-based contrast agents, non-invasive axonal tracing, non-invasive scaffold imaging, scaffold patterning, 3D printed sc...
Cover Page
Rolling circle amplification (RCA) has been widely used to enhance detection signals as its long single‐stranded RCA products can provide multiple binding sites for signal probes for sensitive detections. In the current study, we employ atomic force microscopy (AFM) to monitor the RCA products during the course of the RCA process over time. Subsequ...
Article
A microfluidic system that incorporates both dendrimers and aptamers to detect E. coli O157:H7 is developed. To achieve this, generation 7-polyamidoamine dendrimers were immobilized onto the detection surfaces of PDMS microfluidic channels; subsequently aptamers against E. coli O157:H7 were conjugated onto the microchannel surfaces via the immobili...
Article
Full-text available
To detect sulfamethazine (SMZ) residues in edible animal products, a colorimetric aptasensor that is based on indirect competitive enzyme-linked aptamer assay (ELAA) is developed in this study. This ELAA uses SMZ-specific aptamers as recognition elements and enzyme as the signal readout element. The detection sensitivity and the specificity of the...
Article
Full-text available
An axonal tracer that can be detected by both magnetic resonance imaging (MRI) and fluorescence is of great interest for studying nerve regeneration, particularly for spinal cord injury repairs. In this study, we develop a new type of multifunctional nanoparticle that combines three different functionalities of paramagnetism, fluorescence, and axon...
Article
Full-text available
The main role of condensins is to regulate chromosome condensation and segregation during cell cycles. Recently, it has been suggested in the literatures that subunits of condensin I and condensin II are involved in some human cancers. This paper will first briefly discuss discoveries of human condensins, their components and structures, and their...
Article
A rapid, simple, and sensitive fluorescent immunochromatographic strip test (ICST) based on quantum dots (QDs) has been developed to detect 1-aminohydantoin (AHD), a major metabolite of nitrofurantoin in animal tissues. To achieve this, QD-labeled antibody conjugates, which consist of CdSe/ZnS QDs and monoclonal antibodies, were prepared by an acti...
Article
A multifunctional nanobiomaterial has been developed by deliberately combining functions of superparamagnetism, fluorescence, and axonal tracing into one material. Superparamagnetic iron oxide nanoparticles were first synthesized and coated with a silica layer to prevent emission quenching through core–dye interactions; a fluorescent molecule, fluo...
Article
Each imaging modality has its own merits and intrinsic limitations; therefore, combining two or more complementary imaging modalities has become an interesting area of research. Recently, magnetic ion-doped quantum dots have become an increasingly promising class of optical/magnetic resonance multimodal imaging probes due to their excellent physica...
Article
We report a new two-step microfluidic device that performs efficient, continuous, and high throughput small particle separation. The separation mechanism is based the on combined effects of inertial focusing in a spiral microchannel followed by particle deflection in a straight microchannel. The particle trajectory was studied using 1 and 5.5 μm fl...
Article
The majority of foodborne illnesses and deaths are caused by pathogenic bacteria. Therefore there is an increasingly urgent need for rapid, sensitive and cost-effective detection methods in order to avoid or to respond to outbreaks of such diseases in a timely manner. In an attempt to develop a simple and sensitive fluorescence intensity based micr...
Article
Non-specific cell adsorption is a challenge in sensitive detections using microfluidic systems, such as detecting circulating tumour cells from blood samples. In this report, we present a new strategy to study the combined effects of surface hydrophilicity/hydrophobicity, electric charges and roughness on surface non-fouling properties of a PDMS/SU...
Article
Bacterial cellulose (BC) is secreted by a few strains of bacteria and consists of a cellulose nanofiber network with unique characteristics. Because of its excellent mechanical properties, outstanding biocompatibilities, and abilities to form porous structures, BC has been studied for a variety of applications in different fields, including the use...
Article
Identification and quantification of foodborne pathogens are becoming increasingly important to public health and food safety since the majority of foodborne illnesses and deaths are caused by pathogenic bacteria. Conventional methods for foodborne pathogen detection are time-consuming and laborious due to the requirement of a series of processes i...
Article
Full-text available
Biodegradable scaffolds have been extensively studied due to their wide applications in biomaterials and tissue engineering. However, infections associated with in vivo use of these scaffolds by different microbiological contaminants remain to be a significant challenge. This review focuses on different sterilization techniques including heat, chem...
Article
Full-text available
Bacillus cereus is increasingly recognized as one of the major causes of food poisoning in the industrialized world. In this paper, we describe a sensitive double-antibody sandwich enzyme-linked immunosorbent assay (ELISA) that was developed for rapid detection of B. cereus in food to minimize the risk of contamination. The polyclonal antibody (pAb...
Article
As an important step in sample preparation, sample concentration step helps to improve sampling techniques that are often necessary to detect low levels of pathogenic bacteria in food safety inspections, reducing or completely eliminating the need for time-consuming cell enrichment process for detection. In this study, we investigated strategies to...
Article
Full-text available
Because Schwann cells perform the triple tasks of myelination, axon guidance and neurotrophin synthesis, they are candidates for cell transplantation that might cure some types of nervous-system degenerative diseases or injuries. However, Schwann cells are difficult to obtain. As another option, ectomesenchymal stem cells (EMSCs) can be easily harv...
Article
Full-text available
A new strategy to prepare an ultra non-fouling SU-8/poly(dimethylsiloxane) (PDMS) hybrid microfluidic system is presented. We report a simple method to bond both SU-8 and PDMS surfaces to prepare the hybrid microfluidic device and then simultaneously modify both SU-8 and PDMS surfaces using poly(amidoamine) (PAMAM), a highly hydrophilic dendrimer t...
Article
Rapid detection of pathogenic bacteria in real-world samples, in which low concentration target bacteria usually coexist with a large quantity of interfering particles, is very important in many areas related to public health. In this study, we present our recent efforts in detecting low concentration bacteria in complex media that contain interfer...
Article
Listeria monocytogenes is one of several Gram-positive bacteria known to contain an auxiliary ATPase (SecA2) involved in the Sec secretion of a subset of proteins important to bacterial pathogenesis, including autolysins. It is not known if IspC, a novel surface-associated autolysin essential for full virulence of L. monocytogenes serotype 4b, is S...
Article
Techniques to pattern cells on biocompatible hydrogels allow for the creation of highly controlled cell microenvironments within materials that mimic the physicochemical properties of native tissues. Such technology has the potential to further enhance our knowledge of cell biology and to play a role in the development of novel tissue engineering d...
Article
SU-8-based photonic-microfluidic integrated devices with on-chip beam shaping and collection capabilities were demonstrated in a scattering detection and counting application. Through the proper deployment of the tailored beam geometries via the on-chip excitation optics, excellent coefficients of variation (CV) values were measured for 1-, 2-, and...
Article
A new approach to pattern cells using photochemistry and self-assembled monolayer (SAM) was described in this study. Photocleavable 4,5-dimethoxy-2-nitrobenzyl chloroformate (NVOC) protected amine on an alkanethiol-gold SAM was developed for cell patterning. The cleavage of NVOC and the deprotection of amines on the SAM were controlled spatially by...
Article
A photonic integrated microfluidic device is demonstrated to perform optical excitation and forward scatter collection all on-chip in a planar format. Integrated on-chip optics formed a tailored beam geometry for optimal excitation of particles while a special design modification allowed for on-chip forward collection with the beam shaping capabili...
Article
Full-text available
Fibrin has been widely used in wound healing. However, its benefit for spinal cord injury (SCI) is limited. In this study, we investigated the impact of fibrin scaffolds containing ectomesenchymal stem cells (EMSCs) on histological and behavioral recovery after SCI and compared it with fibrin alone. To achieve this, EMSCs derived from adult rat nas...
Article
Photocaged RGDS is a cell nonadhesive tetrapeptide that can be activated with light to become cell-adhesive. Such molecules can find useful applications in controlling cell adhesion for biological study, drug development, and in forming dynamic, adhesion-controlled biomaterials. Herein, we prepared RGDS peptide photocaged either on the Arg-Gly back...
Article
Full-text available
Listeria monocytogenes serotype 4b is responsible for a high percentage of fatal cases of food-borne infection. In a previous study, we created 15 monoclonal antibodies (MAbs) against a ~77 kDa antigen that is associated with the cell surface of live L. monocytogenes serotype 4b cells. Here we report an extensive characterization of these MAbs to f...
Data
Primers used to amplify fragments coding for possible IspC epitopes that react with the MAbs. a – NdeI restriction site is shown underlined. b – NotI restriction site is shown underlined. (DOC)
Data
Listeria monocytogenes isolates used in this study. a- Indicates the strain used in immunization during the production of the MAbs. (DOC)
Article
Microfluidic interconnects act as bridges to connect microscopic channels with macroscopic environments, enabling the microfluidic device to perform its designed functions. In this study, we report a new method to prepare a reliable PDMS interconnect that is able to handle high throughput applications and can be easily incorporated into PDMS microf...
Article
Full-text available
Fabrication and performance of a functional photonic-microfluidic flow cytometer is demonstrated. The devices are fabricated on a Pyrex substrate by photolithographically patterning the microchannels and optics in a SU-8 layer that is sealed via a poly(dimethylsiloxane) (PDMS) layer through a unique chemical bonding method. The resulting devices el...
Article
A photonic-microfluidic integrated device is demonstrated with excellent and reliable fluorescence detection performance. CV values of 8% for 2.5-μm beads and 14% for 6-μm beads were achieved through the correct deployment of carefully formed excitation beam shapes via integrated on-chip optics even without the use of 3D hydrodynamic focusing or a...
Article
Full-text available
An optofluidic device is demonstrated with photonic components integrated onto the chip for use in fluorescence and scatter detection and counting applications. The device is fabricated by integrating the optical and fluidic components in a single functional layer. Optical excitation on-chip is accomplished via a waveguide integrated with a system...
Article
We report a novel non-fouling passivation method using poly(ethylene glycol) (PEG) engraftment on the surfaces of poly(dimethylsiloxane) (PDMS) microfluidic device sealed with SU-8. To achieve bondings between the PDMS and SU-8 surfaces, PDMS surface was first functionalized with amines by treatments with 3-aminopropyltrimethoxysilane (APTMS) for s...
Article
Full-text available
Listeria monocytogenes serotype 4b is a food-borne pathogen of public health concern, since it accounts for approximately 40% of human listeriosis cases. We have recently identified IspC, a surface-localized peptidoglycan hydrolase, as the antigen recognized by a number of monoclonal antibodies (MAbs) produced against a serotype 4b strain for diagn...
Article
Full-text available
IspC is a novel peptidoglycan (PG) hydrolase that is conserved in Listeria monocytogenes serotype 4b strains and is involved in virulence. The aim of this study was to establish the hydrolytic bond specificity of IspC. Purified L. monocytogenes peptidoglycan was digested by recombinant IspC and the resulting muropeptides were separated by reverse p...
Article
Full-text available
Although many regenerative cell therapies are being developed to replace or regenerate ischaemic muscle, the lack of vasculature and poor persistence of the therapeutic cells represent major limiting factors to successful tissue restoration. In response to ischaemia, stromal cell-derived factor-1 (SDF-1) is up-regulated by the affected tissue to st...
Article
To enhance the CO-tolerance performance of anode catalysts for direct ethanol fuel cells, carbon nanotubes were modified by titanium dioxide (donated as CNTs@TiO2) and subsequently served as the support for the preparation of Pt/CNTs@TiO2 and Pt-Mo/CNTs@TiO2 electrocatalysts via a UV-photoreduction method. The physicochemical characterizations of t...
Article
An approach to control cell adhesion using a photocleavable molecule on chitosan has been developed and studied. Photocleavable 4,5-dimethoxy-2-nitrobenzyl chloroformate (NVOC) was introduced into chitosan to control the surface properties. The two UV illuminations with a photomask controlled the cleavage of NVOC and the presentation of deprotected...
Article
Full-text available
Salmonella enterica subsp. enterica serotype Typhimurium is one of the major causative agents of human gastroenteritis. Here we raised a panel of 45 monoclonal antibodies (MAbs) against ser. Typhimurium DT104 by immunizing mice with formalin-killed bacteria and demonstrated that all the MAbs recognized the bacterial lipopolysaccharide (LPS) antigen...
Article
To demonstrate the ability to efficiently count and identify suspended micron-sized particles by simultaneously detecting their fluorescence emission and light scattering in microfabricated channel, a compact configuration that used a polydimethylsiloxane (PDMS) microfabricated channel as interrogation component, hydrodynamic focusing for particle...
Article
Partially Sulfonated Poly(ether ether ketone) (SPEEK) samples were prepared by modification of corresponding poly(ether ether ketone) (PEEK) with concentrated sulfuric acid. Poly(ether sulfone)(PES) was blended into SPEEK to prepare PES/SPEEK blend membranes by solution casting. The glass transition temperature of blend membranes indicated the mole...
Article
In this work, the rare bacteria-like-sized particles were detected in real-world-like sample circumstances with high concentration interfering particles and fluorescein background using cytometric fashion by simultaneously detecting their fluorescence emission and scattering light on microfluidic device to demonstrate its application of identifying...
Article
Previous studies indicate that neural progenitor cells seeded in fibrin can differentiate into the glia cells and neurons. However, whether fibrin gel can induce differentiation of neural progenitor cells of spinal cord into motoneurons remains to be elucidated. In this study, we prepared a fibrin-based hybrid gel incorporated with laminin and fibr...
Article
A new approach to control cell attachment using photochemistry and self-assembled monolayers (SAMs) has been developed. Poly(ethylene glycol) (PEG) was introduced onto a gold SAM surface to initially create a cell repulsive surface via a photo-cleavable o-nitrobenzyl functional group. This cell repulsive surface was subsequently rendered cell adhes...
Data
1H NMR spectrum of caged R[G]DS tetrapeptide in D2O following UV-irradiation with expanded portions within the insets
Data
1H NMR spectrum of caged-R[G]DS tetrapeptide in D2O with expanded portions within the insets
Article
Full-text available
Studies using cellular therapies, scaffolds, and tubular structured implants have been carried out with the goal to restore functional recovery after spinal cord injury (SCI). None of these therapeutic strategies, by themselves, have been shown to be sufficient to achieve complete restoration of function. To reverse the devastating effects of SCI,...
Article
Full-text available
We demonstrated a simple method for the device design of a staggered herringbone micromixer (SHM) using numerical simulation. By correlating the simulated concentrations with channel length, we obtained a series of concentration versus channel length profiles, and used mixing completion length L(m) as the only parameter to evaluate the performance...
Article
Full-text available
We evaluated the dynamic micromixing performances in slanted groove micromixers (SGM) and staggered herringbone micromixers (SHM) and quantitatively compared their differences using concentration vs. channel length profiles obtained from numerical stimulations. It is found that faster and finer mixing took place in the SHM and the chaotic mixing wa...
Article
As we aim towards enhancing our knowledge of complex cell behaviors and developing intricate cell-based devices and improved therapeutics, it becomes imperative that we be able to control and manipulate the spatial localization of cells. Here we have developed a novel strategy to pattern cells using a hyaluronic acid hydrogel material and photocage...
Conference Paper
Cell behaviors, including proliferation, differentiation, and migration, are known to be influenced to a large extent by the nature of the surrounding microenvironment. Cell micropatterning platforms provide us with tools to control the spatial localization of cells on biomaterial constructs. To date, the vast majority of cell micropatterning techn...
Article
Full-text available
Implantation of tissue-engineered scaffolds is one of the most promising therapeutic strategies for inducing nerve regenerations following spinal cord injuries. In this paper, we report a novel bioengineered hybrid scaffold comprised of three major extracellular matrix (ECM) proteins. ECM-scaffolds (ECM-S) were prepared by gelling fibrinogen, fibro...