- Front Matter: Volume 8719
- Smart Biosensing Strategies at the Cellular and Bacterial Level
- Smart Materials for Biorecognition and Biosensing
- Lab-on-a-Chip Technologies for Biological Sensing
- Electrochemical and Noninvasive Sensing for Rapid Patient Monitoring
- Smart Sensing Platforms and Technologies
- Multispectral Imaging Agents and Systems for Tissue Diagnostics
- Biophotonic Imaging of Tissue and Tissue Phantoms
Optical detection methods have been implemented on micro-fluidic chips containing channels or cavities of different geometries e.g. for colorimetry or fluorescence measurements with excitation within the chip plane [1-2]. The most prominent problem of the read-out from a micro-fluidic chip is the limitation of the optical yield. Without e.g. an immersion liquid for compensation of the total reflection on the boundary, only about 11-13% of rays cross over the boundary from a polymer chip to air. One efficient method to increase the optical yield from a chip is a ray reorientation inside of the chip using an additional surface structure creating new incident refraction conditions on the boundary before rays are leaving the chip. The use of 45°-tilted mirror arrangements for in- and out-coupling of the fluorescence signal from a micro-fluidic chip and the realization of this principle for low-cost fluorescence detection systems have been published [3].
This paper includes the investigation of the effect of different tilt angles of total reflection and metallized-surface mirrors for an analyte volume emitter, using the ray-tracing simulation tool OptiCAD10. Furthermore, an estimation of the influence of a surface-emitted signal for different geometries of metallized detection cells with or without a combination with external lenses on the out-coupling efficiency will be presented. The best result of an out-coupling efficiency increase of 10 times was achieved for a combination of a structured and metallized detection cell with an external cylindrical lens.
Aim of the study was to establish and evaluate a “lab-on-a-chip” system for the detection of bacterial B-agents using Bacillus (B.) thuringiensis as simulant for B. anthracis.
To enable reliable detection of target DNA using PCR assays it is crucial that purified DNA is extracted from the sample matrix. We established chip-based assays for cell lysis, sample concentration, and DNA purification using magnetic particles with special surface modifications and compared these assays with a commercial routine method. DNA yield was determined using quantitative real-time PCR assays with TaqMan probes targeting the cry1Ac gene.
Lab-on-a-chip systems are applicable for point-of-care analysis and provide several advantages in comparison to conventional diagnostic techniques. Purification of DNA and subsequent PCR analysis can be integrated and the instrumentation can be miniaturized. Therefore, such tests can also be useful in medical and veterinary diagnostics.
Side effects of chemotherapy are major problems associated with current cancer treatment. An effective way to minimize these side effects and improve the efficacy of cancer treatment is to deliver drugs specifically targeted to tumors. This can be achieved by encapsulating chemotherapy drugs inside nanoparticles that aggregate in tumors due to the enhanced permeability and retention effect.
In order to monitor the delivery of nanoparticle-drug conjugates, it is important to develop systems that can image the nanoparticles. Since two-photon fluorescent probes can lead to significant reduction of background fluorescence compared to single photon fluorescent probes, two-photon fluorescent nanoparticles were developed through the miniemulsion process, using a conjugated polymer—poly [2-(3-thienyl)ethanol butoxycarbonyl-methyl urethane])—and two surfactants—sodium dodecyl sulfate (SDS) and cetyl trimethylammonium bromide (CTAB).
Nanoparticle size decreased as surfactant concentration increased, and particle size remained constant for surfactant concentrations above the critical micellar concentration (CMC), which was 8.2 μM for SDS and 1 μM for CTAB. The average size of the nanoparticles with surfactants at CMC was 31.67 nm for SDS nanoparticles and 25.60 nm for CTAB nanoparticles. Both nanoparticle systems exhibited strong one-photon and two-photon fluorescent signals. Fluorescence microscopy demonstrated these nanoparticles were able to penetrate rat cardiomyocytes. The results suggest these nanoparticles may potentially be used for high-contrast cell imaging.
The aim of nanodiagnostics is to identify disease at its earliest stage, particularly at the molecular level. Nanoparticlebased molecular imaging has set a unique platform for cellular tracking, targeted diagnostic studies, and imagemonitored therapy. In the preclinical setting, several modalities, such as fluorescence, positron emission tomography (PET), magnetic resonance imaging (MRI), computed tomography (CT) and ultrasound imaging are used for imaging of the cardiovascular system. Although this conventional imaging describes the extent and severity of cardiovascular diseases such as atherosclerosis or ischemia, molecular imaging is needed to identifying precursors of disease development and progression. Bringing multimodality capability to molecular imaging will harness the complimentary abilities of different techniques, thus optimizing the overall resolution and sensitivity of the resulting scans. The enhanced imaging details will permit more precise diagnosis and control of treatments.
In this paper, we present the synthesis and characterization of a dual-imaging contrast agent based on bifunctional gold nanoparticles designed for the targeting of tissue ACE (angiotensin-converting enzyme) and monitoring of cardiovascular diseases. Lisinopril (an ACE inhibitor) was selected as the targeting agent and derivatized with thioctic acid for a stronger anchoring onto gold nanoparticles. A Gd(DOTA) complex was chosen as the MRI tag. The gold core serves as the CT contrast agent. The new nanoprobes prepared not only possess the ability to target tissue ACE but also provided bimodal imaging capabilities (CT and MRI). This bimodal molecular imaging will improve the ability to accurately target diseased tissue at a very early stage, thus diagnosing and then treating patients in the most efficient way.