[Show abstract][Hide abstract] ABSTRACT: In this work, high-quality antibody functionalized Fe3O4 magnetic nanoparticles are synthesized. Such physical characterizations as particle morphology, particle size, stability, and relaxivity of magnetic particles are investigated. The immunoreactivity of biofunctionalized magnetic nanoparticles is examined by utilizing immunomagnetic reduction. The results show that the mean diameter of antibody functionalized magnetic nanoparticles is around 50 nm, and the relaxivity of the magnetic particles is 145 (mM·s)−1. In addition to characterizing the magnetic nanoparticles, the feasibility of using the antibody functionalized magnetic nanoparticles for the contrast medium of target magnetic resonance imaging is investigated. These antibody functionalized magnetic nanoparticles are injected into mice bearing with tumor. The tumor magnetic-resonance image becomes darker after the injection and then recovers 50 hours after the injection. The tumor magnetic-resonance image becomes the darkest at around 20 hours after the injection. Thus, the observing time window for the specific labeling of tumors with antibody functionalized magnetic nanoparticles was found to be 20 hours after injecting biofunctionalized magnetic nanoparticles into mice. The biopsy of tumor is stained after the injection to prove that the long-term darkness of tumor magnetic-resonance image is due to the specific anchoring of antibody functionalized magnetic nanoparticles at tumor.
Journal of Nanomaterials 01/2014; 2014:1-7. DOI:10.1155/2014/351848 · 1.64 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: By conjugating antibodies on magnetic nanoparticles, target antigens can be quantitatively detected by measuring the magnetic signals of the magnetic nanoparticles due to their association with target antigens. This method of detection is called magnetically labeled immunoassay. The assay characteristics of magnetically labeled immunoassay have been reported widely. However, the immuno-reaction kinetics of magnetically labeled immunoassay has not been studied. In this work, the reaction rates between magnetic nanoparticles and target antigens are measured at various temperatures. It is found that the temperature dependent reaction rate obeys Arrhenius's equation, which shows the collision frequency and activation energy for the immuno-reaction between antibody-functionalized magnetic nanoparticles and target antigens. The carcinoembryonic antigen, which is a regular blood bio-marker for in-vitro diagnosis of colorectal cancer, is used as a target antigen for the example.
[Show abstract][Hide abstract] ABSTRACT: Nanomagnetically labeled immunoassays have been demonstrated to be promisingly applied in clinical diagnosis. In this work, by using antibody-functionalized magnetic nanoparticles and a high-temperature superconducting quantum interference device ac magnetosusceptometer, the assay properties for vascular endothelial growth factor (VEGF) in serum are investigated. By utilizing the assay method so-called immunomagnetic reduction, the properties of assaying VEGF are explored. In addition, the VEGF concentrations in serum samples of normal people and patients with either colorectal or hepatocellular cancer are detected. The experimental results show that the low-detection limit for assaying VEGF is 10 pg/mL, which is much lower than the clinical cut-off VEGF concentration of 50 pg/mL for diagnosing malignancy. Besides, there are no significant interference effects on assaying VEGF from hemoglobin, conjugated bilirubin, and triglyceride. The VEGF concentrations in serum samples donated by normal people and patients with hepatocellular carcinoma or colorectal cancer are detected. A clear difference in VEGF concentrations between these two groups is found. These results reveal the feasibility of applying nanomagnetically labeled immunoassay to clinics.
Journal of Nanomaterials 10/2013; 2013(8). DOI:10.1155/2013/695276 · 1.64 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The HTS superconducting quantum interference devices (SQUID) magnetometers meets the requirement for the early-stage or hard-to-detect in-vitro diagnosis because of its ultrahigh sensitivity. For example, the demand for assaying the ultra-low-concentration biomarkers of tumors is always existing. It would be better to quantitatively detect the vascular endothelial growth factor (VEGF) at the concentration of 1 pg/ml for diagnosing the early-stage malignancy. In this work, by using the HTS SQUID-based ac magnetosusceptometer and biofunctionalized magnetic nanoparticles, the low-detection limit for VEGF is sub-pg/ml. Furthermore, the clear difference in the VEGF concentrations in sera was found between normal people and tumor patients. Another example to demonstrate the high sensitivity and high specificity of the immunoassay based on the HTS SQUID ac magnetosusceptometer is the detection of biomarkers for Alzheimer's Disease. The biomarkers for Alzheimer's Disease in plasma are very rare (around 1-100 pg/ml). It is hardly possible to assay the biomarkers in plasma. Here, it has been demonstrated that the HTS SQUID ac magnetosusceptometer can detect the biomarkers at very low concentrations ( ~ 1 pg/ml). Through the assays on the biomarkers in plasma of more than 100 people, the clinical accuracy is almost 90%. These results show the niches of clinical applications using the HTS SQUID ac magnetosusceptometer.
[Show abstract][Hide abstract] ABSTRACT: To image magnetic nanoparticles (MNPs) on animal bodies, physicians often use magnetic resonance imaging to determine the superparamagnetic characteristics of MNPs during preoperative analysis. However, magnetic resonance imaging is unsuitable for other biomedical applications, such as the curative surgical resection of tumors or pharmacokinetic studies of MNPs, because of the requirement of nonmetal environments and high financial cost of frequent examination, respectively. Thus, researchers have proposed other nonmagnetic imaging technologies, such as fluorescence, using multimodal MNPs with nonmagnetic indicators. The development of a magnetic instrument based on the other magnetic characteristics of MNPs avoids the disadvantages of multimodal MNPs, including the biosafety risk. On the basis of the alternating current susceptibility of MNPs, previous research has demonstrated the magnetic examination of scanning superconducting-quantum-interference-device biosusceptometry (SSB). This study, using a low-noise charge-coupled-device type of a video camera, reports the integration of SSB and charge-coupled-device to immediately image the magnetic signals on animal bodies or organic tissue. This real-time imaging by SSB increases the usefulness of MNPs for more clinical applications, including the imaging-guided curative surgical resection of tumors.
[Show abstract][Hide abstract] ABSTRACT: In this work, we set up a low-cost high-T-c SQUID-based low-field nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) system without mu-metal. In order to reduce the surrounding noise, we built the shielded box and shielded cylinder made out of aluminum. For NMR and MRI measurements, we apply the gradient compensation field to cancel the field inhomogeneity in our lab to obtain a narrow linewidth NMR spectrum of 0.8 Hz from a 10-ml water specimen. In the absence of chemical shifts, the J-couplings of trimethyl phosphate and trifluoroethanol are demonstrated in trials of the proposed scheme. Furthermore, the 2-D images of water specimen and mini tomato with high-image resolution of better than 2 mm are obtained by using our low-field MRI system. Our high-T-c SQUID-based low-field MRI system promises a low-cost and high imaging quality in microtesla magnetic fields.
[Show abstract][Hide abstract] ABSTRACT: Immunomagnetic reduction assay is used to quantitatively detect bio-molecules. Many reports show that the to-be-detected bio-molecular concentration dependent reduction in the alternative-current (ac) magnetic susceptibility of a reagent is governed by the logistic function, which is a four-parameter function. One of the parameters relates to the increase in the rate of the magnetic reduction signal when the concentration of to-be-detected bio-molecules is increased. Theoretically, this parameter is attributed to the clustering associations between to-be-detected bio-molecules and labeling particles in the reagent. In an immunomagnetic reduction assay, the bioactive labeling particles are anti-body-functionalized magnetic nanoparticles. However, there is no detailed information about the effect of the clustering associations on this parameter. In this work, the clustering association is manipulated by controlling the concentrations of anti-body-functionalized magnetic nanoparticles in the reagent. The experimental results show that higher values for this parameter are obtained with concentrated anti-body-functionalized magnetic nanoparticles in the reagent. This implies that particle clustering is enhanced by an increase in the concentration of the bio-functionalized magnetic particles. It is also demonstrated that the particle clustering effect dominates the increased rate of the magnetic reduction signal.
[Show abstract][Hide abstract] ABSTRACT: The low limit of detection (LLD) plays an important role in biomolecular assays, especially for early-stage assays. Biomolecular detections usually involve the use of two main elements: a reagent and an analyzer, which both greatly contribute to the LLD. In this work, the relationships among the LLD and reagent-related factors are investigated. The to-be-detected biomolecule is c-reactive protein (CRP) as an example. The assay method is immunomagnetic reduction (IMR). The components of reagent are Fe3O4 magnetic nanoparticles bio-functionalized with antibodies against CRP, dispersed in pH-7.4 phosphate buffered saline solution. Several key factors of the reagent, such as particle concentration, volume ratio of reagent to sample, and particle size, are manipulated to optimize the LLD of detecting CRP.
[Show abstract][Hide abstract] ABSTRACT: Reagents for magnetically labeled immunoassay on human Hb and human HbA1c have been synthesized. The reagents consist of Fe3O4 magnetic particles biofunctionalized with antibodies against Hb and HbA1c. It has been demonstrated that the reagents can be applied to quantitatively detect Hb and HbA1c by using immunomagnetic reduction assay. In addition to characterizing the assay properties, such as the standard curve and the low-detection limit, the stability of reagents is investigated. To do this, the temporal dependence of particle sizes and the bio-activity of reagents are monitored. The results show that the reagents are highly stable when stored at 2–8 °C. This means that the reagents synthesized in this work are promising for practical applications.
Journal of Magnetism and Magnetic Materials 01/2013; 326:147–150. DOI:10.1016/j.jmmm.2012.08.029 · 1.97 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Magnetic nanoparticles biofunctionalized with antibodies are useful for specifically labeling target biomolecules. By measuring magnetic signals after the association between biofunctionalized magnetic nanoparticles and target biomolecules, the concentration of target biomolecules can be quantitatively detected. One of measuring methodologies is so-called immunomagnetic reduction (IMR), in which the reduction in ac magnetic susceptibility of magnetic reagent is a function of the concentration of target biomolecules. In this letter, the relationship between the magnetic reduction signal of reagent and the concentration of target biomolecules is explored. According to the experimental results on various kinds of target biomolecules, such as proteins and chemicals, the magnetic reduction signal as a function of concentration of various target biomolecules can be scaled to a universal curve. This universal curve is a logistic function. This implies that there exists a unique mechanism for the association between the target biomolecules and biofunctionalized magnetic nanoparticles in an IMR assay.
[Show abstract][Hide abstract] ABSTRACT: Although there is a consensus on the reduced levels of Aβ1-42 in the CSF of patients with AD, studies of plasma Aβlevels were inconsistent and have limited clinical value. We developed an immunomagnetic reduction assay (IMR) to determine the plasma levels of Aβ.We surveyed patients with varying AD severity (CDR = 0.5, n=16; CDR ≥1, n=18) and controls (n=26). Significant group differences were apparent in the levels of Aβ1-42 (F = 5.54, p = 0.002) and the Aβ1-42/Aβ1-40 ratio (F = 24.198, p <0.001). Post-hoc analyses showed significant differences in the Aβ1-42 levels of controls and AD patients (p = 0.001) and in the Aβ1-42/Aβ1-40 ratio of control, MCI and AD subjects (all p ≤0.001). Regression analysis of Aβ1-42/Aβ1-40 ratios on dementia severity showed an adjusted R2 of 0.553 (p = 0.001).We identified a cut-off of 16.1 pg/ml for Aβ1-42 to differentiate control subjects from patients (both AD and MCI) with 85.3% sensitivity and 88.5% specificity. We also obtained a cut-off value of 0.303 for Aβ1-42/Aβ1-40 ratios with 85.3% sensitivity and 96.2% specificity. APOE ε4 carriers had significantly higher Aβ1-42/Aβ1-40 ratios than the non-carriers (F = 4.839, p = 0.015). An independent group of case-control subjects validated both cut-off values for Aβ1-42/Aβ1-40 (100% sensitivity and 83.3% specificity) and for Aβ1-42 (100% sensitivity and 75.3% specificity). In a subgroup of longitudinal follow-up study, we found that the plasma Aβ was relatively stable with an interval of 3 approximately 3 months. In conclusion, we found that the plasma Aβ1-42 is a useful biomarker for AD. The Aβ1-42/Aβ1-40 ratio improves the diagnostic power of the plasma Aβ biomarkers. The iron nanoparticles and IMR provides a novel method to measure plasma Aβ and could serve as an important clinical tool for the diagnosis of neurodegenerative diseases.
Current Alzheimer research 08/2012; 9(10). DOI:10.2174/156720512804142967 · 3.89 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The allele HLA-DRB1*03:20, a variant of DRB1*03, was first reported to the IMGT HLA database in April 2001 without indication on the ethnicity of the blood donor (Cell ID: HC 125775). We found a Taiwanese volunteer hematopoietic stem cell donor carries DRB1*03:20 by a sequence-based typing (SBT) method. The DNA sequence of DRB1*03:20 is identical to the sequence of DRB1*03:01:01 in exon 2, except a nucleotide substitution at position 341(T→C) (GTT→GCT at codon 85). The nucleotide replacement produced an amino acid variation at residue 85 (V→A). We hypothesize that DRB1*03:20 was probably derived from DRB1*03:01:01 via a nucleotide point mutation event. The probable HLA haplotype in association with DRB1*03:20 was deduced as A*11:02-B*58:01-C*07:02-DRB1*03:20. We here report the Taiwanese/Chinese ethnicity of DRB1*03:20.
International Journal of Immunogenetics 08/2012; 40(3). DOI:10.1111/j.1744-313X.2012.01151.x · 1.25 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: By specifically bio-functionalizing magnetic nanoparticles, magnetic nanoparticles are able to label target bio-molecules. This property can be applied to quantitatively detect molecules invitro by measuring the related magnetic signals of nanoparticles bound with target molecules. One of the magnetic signals is the reduction in the mixed-frequency ac magnetic susceptibility of suspended magnetic nanoparticles due to the molecule-particle association. Many experimental results show empirically that the molecular-concentration dependent reduction in ac magnetic susceptibility follows the logistic function. In this study, it has been demonstrated that the logistic behavior is originated from the growth of particle sizes due to the molecule-particle association. The analytic relationship between the growth of particle sizes and the reduction in ac magnetic susceptibility is developed.
[Show abstract][Hide abstract] ABSTRACT: We report here the novel variant of HLA-DRB1*09:01, DRB1*09:01:08, discovered in a Taiwanese volunteer bone marrow donor by a sequence-based typing (SBT) method. The DNA sequence of DRB1*09:01:08 is identical to the sequence of DRB1*09:01:02 in exon 2 except a silent mutation at nucleotide position 261(C→T) (GCC→GCT at codon 58). We hypothesize DRB1*09:01:08 was probably derived from DRB1*09:01:02 via a nucleotide point mutation event. The plausible HLA-A, HLA-B and HLA-DRB1 haplotype in association with DRB1*09:01:08 was deduced as A*02:07-B*46:01-DRB1*09:01:08.
International Journal of Immunogenetics 07/2012; 40(2). DOI:10.1111/j.1744-313X.2012.01143.x · 1.25 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: This study uses a sensitive, high-Tc SQUID-detected nuclear magnetic resonance spectrometer in magnetically unshielded environments to discriminate liver tumors in rats, by characterizing the longitudinal relaxation rate, T1−1. The high-Tc SQUID-based spectrometer has a spectral line width of 0.9Hz in low magnetic fields. It was found that relaxation rate for tumor tissues is (3.6 ± 0.02) s−1 and the relaxation rate for normal tissues is (7.7 ± 0.02) s−1. The difference in the longitudinal relaxation rates suggests that water structures around the DNA of cancer cells are different from those of normal tissues. The optimized detection sensitivity for the established system is 0.21 g at the present stage. It is concluded that T1−1 can be used to distinguish cancerous tissues from normal tissues. The high-Tc, SQUID-detected NMR and MRI in magnetically unshielded environments may also be useful for discriminating other tumors.
Journal of Instrumentation 06/2012; 7(06). DOI:10.1088/1748-0221/7/06/P06005 · 1.40 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We investigated the relaxation of protons in magnetic fluids using a high-Tc SQUID magnetometer. It was found that the longitudinal relaxation rate, 1/T1, is slower than the transverse relaxation rate, 1/T2, for ferrofluids in the same field. This is due to the fact that the 1/T1 process involves returning the magnetization to the z-direction, which automatically involves the loss of magnetization in the x-y plane governed by the 1/T2 process. Additionally, 1/T1 and 1/T2 at high temperatures are slower than the corresponding relaxation rates at low temperatures, which is due to the enhanced Brownian motion of nanoparticles at high temperatures.
[Show abstract][Hide abstract] ABSTRACT: The application of the assay methodology, called immunomagnetic reduction, using bio-functionalized magnetic nanoparticles as labeling markers for chloramphenicol was investigated. The reduction in the alternative-current (ac) magnetic susceptibility χac of magnetic nanoparticles caused by the association between magnetic nanoparticles and chloramphenicol was detected as a function of the concentration of chloramphenicol. In this study, the characterizations used to detect chloramphenicol, such as low-detection limit and interference, were also conducted. Furthermore, the extracting processes for chloramphenicol from shrimp were explored. Thus, the platform for detecting chloramphenicol residue in shrimp via immunomagnetic reduction was demonstrated. Such platform showed features of a 0.1-ppb low-detection limit, low interference from other kinds of antibiotics, and easy operation.
[Show abstract][Hide abstract] ABSTRACT: Nervous necrosis virus (NNV) is the cause of viral nervous disease, which is a serious constraint on production for grouper aquaculture. Real-time PCR is commonly used to detect and quantify NNV, has the disadvantages of being expensive and technically demanding. In this study, an immunomagnetic reduction (IMR) assay was developed as a rapid and cost-effective alternative to real-time PCR. This method used magnetic nanoparticles conjugated with antibodies specific for viral surface antigens to detect NNV in grouper tissue samples. The association of NNV with the antibody-conjugated magnetic particles resulted in a reduction in magnetic signal, which was strongly correlated with the concentration of NNV, as determined by real-time PCR. Grouper larvae were prepared for testing using a viral extraction buffer which provided a rapid, 15-min method of extracting viral antigens and had an extraction efficiency of higher than 80%. In addition, this study proposes using magnetic nanoparticles as labeling markers and as an assaying reagent for NNV. The magnetic nanoparticles are functionalized with antibodies against the viral surface of NNV and are able to associate specifically with NNV. The reduction of the magnetic signals comes from the association between magnetic particles and NNV, and relates to the concentration of NNV. The results show that the detected concentrations of NNV are highly correlated to those detected by real-time PCR.
[Show abstract][Hide abstract] ABSTRACT: We report here two novel variants of HLA-A*02 allele, A*02:319 and A*02:01:64, discovered in two Taiwanese unrelated volunteer bone marrow donors by sequence-based typing (SBT) method. The DNA sequence of A*02:319 is identical to A*02:07 in exons 2 and 3 but varies with one nucleotide at codon 9 (TTC->TCC). The variation caused one amino acid substitution at residue 9 (F->S). On the other hand, the DNA sequence of A*02:01:64 is identical to the sequence of A*02:01:01:01 in exons 2 and 3 except a silent mutation at codon 114 (CAC->CAT). The probable HLA-A, HLA-B and HLA-DRB1 haplotypes in association with A*02:319 and A*02:01:64 were deduced as A*02:319-B*46:01-DRB1*04 and A*02:01:64-B*38:02-DRB1*16:02, respectively.
International Journal of Immunogenetics 01/2012; 39(3):261-3. DOI:10.1111/j.1744-313X.2011.01080.x · 1.25 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We report here two novel HLA-B alleles, B*46:13:03 and B*15:189, discovered in two Taiwanese volunteer bone marrow donors. The sequence of B*15:189 has a nucleotide sequence possibly derived from a recombination event between HLA-B*39:01:01 and B*15:01:01:01, while the origin of the sequence B*46:13:03 was less obvious to postulate, considering the low frequency of B*46:13 in the general population and the silent mutations involved. Our report here adds further HLA polymorphism to the growing lists of HLA-B*46 and HLA-B*15 and provides an additional HLA information for donor search programme for patients undergoing transplant.
International Journal of Immunogenetics 08/2011; 38(6):539-42. DOI:10.1111/j.1744-313X.2011.01030.x · 1.25 Impact Factor