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1.
ACS Appl Mater Interfaces ; 11(29): 26518-26527, 2019 Jul 24.
Artigo em Inglês | MEDLINE | ID: mdl-31283174

RESUMO

Two-dimensional (2D) material nanocomposites have emerged as a material system for discovering new physical phenomena and developing novel devices. However, because of the low density of states of most two-dimensional materials such as graphene, the heterostructure of nanocomposites suffers from an enhanced depletion region, which can greatly reduce the efficiency of the charge carrier transfer and deteriorate the device performance. To circumvent this difficulty, here we propose an alternative approach by inserting a second 2D mediator with a heavy effective mass having a large density of states in-between the heterojunction of 2D nanocomposites. The mediator can effectively reduce the depletion region and form a type-II band alignment, which can speed up the dissociation of electron-hole pairs and enhance charge carrier transfer. To illustrate the principle, we demonstrate a novel stretchable photodetector based on the combination of graphene/ReS2/perovskite quantum dots. Two-dimensional ReS2 acts as a mediator in-between highly absorbing perovskite quantum dots and a high-mobility graphene channel and a thiol-based linker between the ReS2 and the perovskite. It is found that the optical sensitivity can be enhanced by 22 times. This enhancement was ascribed to the improvement of the charge transfer efficiency as evidenced by optical spectroscopy measurements. The produced photosensors are capable of reaching the highest reported value of photoresponsivity (>107 A W-1) and detectivity compared to previously studied stretchable devices. Mechanical robustness with tolerable strain up to 100% and excellent stability make our device ideal for future wearable electronics.

2.
Biosens Bioelectron ; 130: 73-80, 2019 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-30731348

RESUMO

Current genetic detection methods require gene isolation, gene amplification and detection with a fluorescent-tagged probe. They typically require sophisticated equipment and expensive fluorescent probes, rendering them not widely available for rapid acute infection diagnoses at the point of care to ensure timely treatment of the diseases. Here we report a rapid genetic detection method that can detect the bacterial gene directly from patient stools using a piezoelectric plate sensor (PEPS) in conjunction with a continuous flow system with two temperature zones. With stools spiked with sodium dodecyl sulfate (SDS) in situ bacteria lysing and DNA denaturation occurred in the high-temperature zone whereas in situ specific detection of the denatured DNA by the PEPS occurred in the lower-temperature zone. The outcome was a rapid genetic detection method that directly detected bacterial genes from stool in < 40 min without the need of gene isolation, gene amplification, or expensive fluorescent tag but with polymerase chain reaction (PCR) sensitivity. In 40 blinded patient stools, it detected the toxin B gene of Clostridium difficile with 95% sensitivity and 95% specificity. The all-electrical, label-free nature of the detection further supports its potential as a low-cost genetic test that can be used at the point of care.


Assuntos
Proteínas de Bactérias/isolamento & purificação , Toxinas Bacterianas/isolamento & purificação , Técnicas Biossensoriais , Clostridium difficile/isolamento & purificação , Fezes/microbiologia , Proteínas de Bactérias/química , Toxinas Bacterianas/química , Clostridium difficile/genética , Clostridium difficile/patogenicidade , Humanos , Dodecilsulfato de Sódio
3.
Rev Sci Instrum ; 90(1): 015006, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30709230

RESUMO

Mammography is the only Food and Drug Administration approved breast cancer screening method. The drawback of the tumor image in a mammogram is the lack of tumor depth information as it is only a 2-dimensional projection of a 3-dimensional (3D) tumor. In this work, we investigated 3D tumor imaging by assessing tumor depth information using a set of piezoelectric fingers (PEFs) with different probe sizes which were known to be capable of eliciting tissue elastic responses to different depths and tested it on model tumor tissues consisted of gelatin with suspended clay inclusions. The locations of the top and bottom surfaces of an inclusion were resolved by solving a simple spring model using the elastic measurements of the PEFs of different probe sizes as the input. The lateral sizes of an inclusion were determined as the full width at half maximum of the Gaussian fit to the measured lateral tumor elastic modulus profile. The obtained lateral inclusion sizes were in close agreement with the actual values, and the deduced depth profiles of an inclusion also agreed with the actual depth profiles so long as the bottom surface of the inclusion was within the depth sensitivity of the PEF with the largest probe size. This work offers a simple non-invasive method to predict the extent of a tumor in all 3 dimensions. The method is also non-radioactive.


Assuntos
Neoplasias da Mama/diagnóstico por imagem , Eletricidade , Imagem Tridimensional/instrumentação , Módulo de Elasticidade
4.
Biosens Bioelectron ; 119: 221-229, 2018 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-30142581

RESUMO

We have investigated amplification-free in situ double-stranded mutation detection in urine in the concentration range 10-19 M - 10-16 M using piezoelectric plate sensors (PEPs). The detection was carried out in a close-loop flow with two temperature zones. The 95 °C high-temperature zone served as the reservoir where the sample was loaded and DNA de-hybridized. The heated urine was cooled flowing through a 1 m long tubing immersed in room-temperature water bath at a flow rate of 4 ml/min to reach the detection cell at the desired temperature for the detection to take place. With hepatitis B virus double mutation (HBVDM) and KRAS G12V point mutation as model double mutations, it is shown that PEPS was able to detect double-stranded HBVDM and KRAS with 70% detection efficiency or better at concentration as low as 10-19 M against single-stranded mutation detection at the same concentrations, which was validated by the following in situ fluorescent reporter microspheres (FRMs) detection as well as microscopic visualization of the FRMs bound to the captured mutant on the PEPS surface. Furthermore, the same double-stranded mutation detection efficacy was demonstrated at 10-19 M - 10-16 M in a background of 250-fold wildtype for HBVDM and 1000-fold wildtype for KRAS. Also demonstrated was detection of KRAS mutation at 10-19 M - 10-16 M of SW480 DNA fragments in urine.

5.
Carbohydr Polym ; 195: 218-224, 2018 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-29804971

RESUMO

Investigations into the piezoelectricity of natural polymers is a continuing area of interest due to their potential role in the complex interplay of mechanical and electrical forces present in biological organisms. Their synthetic counterparts, when electrospun using the air gap electrospinning method, are known to have increased crystallinity and tensile strength as compared to randomly aligned nanofibers composed of the same constituent polymers. Using the air gap electrospinning method with the naturally-occurring, semi-crystalline polymer chitin, the nanofibers were determined to have a 300% increase in tensile strength over randomly collected ones. Additionally, a 400% increase in piezoelectric response in the aligned nanofiber chitin mats was measured. The increased tensile strength and piezoelectricity in aligned chitin nanofibers is a consequence of an increase in α-chitin crystallinity in the nanofibers induced by the air gap collection method.

6.
Adv Mater ; 29(43)2017 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-28991394

RESUMO

A stretchable, flexible, and bendable random laser system capable of lasing in a wide range of spectrum will have many potential applications in next- generation technologies, such as visible-spectrum communication, superbright solid-state lighting, biomedical studies, fluorescence, etc. However, producing an appropriate cavity for such a wide spectral range remains a challenge owing to the rigidity of the resonator for the generation of coherent loops. 2D materials with wrinkled structures exhibit superior advantages of high stretchability and a suitable matrix for photon trapping in between the hill and valley geometries compared to their flat counterparts. Here, the intriguing functionalities of wrinkled reduced graphene oxide, single-layer graphene, and few-layer hexagonal boron nitride, respectively, are utilized to design highly stretchable and wearable random laser devices with ultralow threshold. Using methyl-ammonium lead bromide perovskite nanocrystals (PNC) to illustrate the working principle, the lasing threshold is found to be ≈10 µJ cm-2 , about two times less than the lowest value ever reported. In addition to PNC, it is demonstrated that the output lasing wavelength can be tuned using different active materials such as semiconductor quantum dots. Thus, this study is very useful for the future development of high-performance wearable optoelectronic devices.

7.
Methods Mol Biol ; 1572: 327-348, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28299698

RESUMO

We have examined in situ detection of single-nucleotide KRAS mutations in urine using a (Pb(Mg1/3Nb2/3)O3)0.65(PbTiO3)0.35 (PMN-PT) piezoelectric plate sensor (PEPS) coated with a 17-nucleotide (nt) locked nucleic acid (LNA) probe DNA complementary to the KRAS mutation without DNA isolation and amplification. In situ mutant (MT) DNA in urine in a wild type (WT) background was carried out at a flow rate of 4 mL/min and at 63 °C with the PEPS vertically situated at the center of the flow. Both the temperature and the impingement flow force discriminated the wild type. Under these conditions PEPS was shown to specifically detect KRAS MT in situ within 30 min with an analytical sensitivity of 60 copies/mL in a clinically relevant background of WT with concentrations 1000-fold greater than that of MT without DNA isolation, amplification, or labeling. For validation, detection was performed in a mixture of blue MT fluorescent reporter microspheres (FRMs) (MT FRMs) that bound to only the captured MT, and orange WT FRMs that bound to only the captured WT. The captured blue MT FRMs still outnumbered the orange WT FRMs by a factor of 4-1 even though WT was 1000-fold of MT in urine, illustrating the specificity of the point mutation detection.


Assuntos
Técnicas Biossensoriais/métodos , DNA Tumoral Circulante , Análise Mutacional de DNA/métodos , Dosagem de Genes , Mutação , Mutação Puntual , Proteínas Proto-Oncogênicas p21(ras)/genética , DNA Tumoral Circulante/urina , Sondas de DNA , Humanos , Microscopia de Fluorescência , Sensibilidade e Especificidade
8.
ChemistrySelect ; 2(24): 7332-7339, 2017 Aug 22.
Artigo em Inglês | MEDLINE | ID: mdl-30410961

RESUMO

We have synthesized charge-neutral, stable, non-cytotoxic, bright, near-infrared (NIR) SnS quantum dots (QDs) by first making Cysteamine-capped SnS QDs in glycerol under acidic conditions followed by lengthening the capping molecule with peptide bonds by reacting the capping molecules with glycine and subsequent heat treatment at 200°C for 4 hours. The obtained stable SnS QDs exhibited a band gap of 1.5 eV and a strong, narrow NIR emission peak at 830 nm with a quantum yield of 4.6%. The suspension could be stable for more than 1 month without aggregation or emission decay. The positively charged SnS QDs were further neutralized by 3-mercaptoproprionic acid (MPA) through electrostatic attraction. The MPA neutralized SnS QDs were shown to be non-cytotoxic at concentrations 6 times the typical QDs concentration for immunostaining. Low-noise, optimal NIR immunofluorescent imaging of vascular endothelial growth factor (VEGF) on 3T3 cells and Tn antigen on HT29 cells was achieved by using streptavidin (SA)-linked MPA-neutralized SnS QDs with a SA:QD molar ratio of 22:1 to bind to biotinylated secondary antibody bound on the primary antibody that was bound on the targeted antigen on the cell membrane with a high signal-to noise ratio (SNR) of 35.

9.
J Colloid Interface Sci ; 484: 17-23, 2016 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-27572611

RESUMO

Methylammonium lead bromide (CH3NH3PbBr3) thin films and nanocrystals are useful for solar cells and LED applications. In order to improve stability in ambient environment, CH3NH3PbBr3 nanocrystals have been synthesized using oleylamine as capping molecule. It was found that by increasing the oleylamine to CH3NH3PbBr3 perovskite ratio (OPR), the photoluminescence wavelengths of CH3NH3PbBr3 nanocrystals could be varied from 505nm (green) to 450nm (blue). The change in emission wavelength is associated with a morphology change from nanoplatelets of ∼10nm width at OPR<1 to nanoparticles of ∼3nm diameter at OPR>1. It is suggested that the morphology change of nanocrystals is a result of geometric packing constraint of the sizes of oleylamine and PbBr3 octahedra. The nanocrystals with OPR=0.75 maintain photoluminescence property for more than 6months in ambient condition and can sustain temperature of 150°C for 30min.

10.
Analyst ; 141(4): 1421-33, 2016 Feb 21.
Artigo em Inglês | MEDLINE | ID: mdl-26783561

RESUMO

We have examined the in situ detection of a single-nucleotide KRAS mutation in urine using a (Pb(Mg1/3Nb2/3)O3)0.65(PbTiO3)0.35 (PMN-PT) piezoelectric plate sensor (PEPS) coated with a 17-nucleotide (nt) locked nucleic acid (LNA) probe DNA complementary to the KRAS mutation. To enhance the in situ mutant (MT) DNA detection specificity against the wild type (WT), detection was carried out in a flow with a flow rate of 4 mL min(-1) and at 63 °C with the PEPS vertically situated at the center of the flow in which both the temperature and the flow impingement force discriminated the wild type. Under such conditions, PEPS was shown to specifically detect KRAS MT in situ with 60 copies per mL analytical sensitivity in a background of clinically-relevant 1000-fold more WT in 30 min without DNA isolation, amplification, or labeling. For validation, this detection was followed with detection in a mixture of blue MT fluorescent reporter microspheres (FRMs) (MT FRMs) that bound to only the captured MT and orange WT FRMs that bound to only the captured WT. Microscopic examinations showed that the captured blue MT FRMs still outnumbered the orange WT FRMs by a factor of 4 to 1 even though WT was 1000-fold of MT in urine. Finally, multiplexed specific mutation detection was demonstrated using a 6-PEPS array each with a probe DNA targeting one of the 6 codon-12 KRAS mutations.


Assuntos
Técnicas Biossensoriais/métodos , Mutação Puntual , Polimorfismo de Nucleotídeo Único , Proteínas Proto-Oncogênicas p21(ras)/genética , Proteínas Proto-Oncogênicas p21(ras)/urina , Sequência de Bases , Humanos , Sondas de Oligonucleotídeos/química , Sondas de Oligonucleotídeos/genética , Oligonucleotídeos/química , Oligonucleotídeos/genética
11.
Rev Sci Instrum ; 87(12): 124301, 2016 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-28040934

RESUMO

We have investigated the development of a handheld 4 × 1 piezoelectric finger (PEF) array breast tumor detector system towards in vivo patient testing, particularly, on how the duration of the DC applied voltage, the depression depth of the handheld unit, and breast density affect the PEF detection sensitivity on 40 patients. The tests were blinded and carried out in four phases: with DC voltage durations 5, 3, 2, to 0.8 s corresponding to scanning a quadrant, a half, a whole breast, and both breasts within 30 min, respectively. The results showed that PEF detection sensitivity was unaffected by shortening the applied voltage duration from 5 to 0.8 s nor was it affected by increasing the depression depth from 2 to 6 mm. Over the 40 patients, PEF detected 46 of the 48 lesions (46/48)-with the smallest lesion detected being 5 mm in size. Of 28 patients (some have more than one lesion) with mammography records, PEF detected 31/33 of all lesions (94%) and 14/15 of malignant lesions (93%), while mammography detected 30/33 of all lesions (91%) and 12/15 of malignant lesions (80%), indicating that PEF could detect malignant lesions not detectable by mammography without significantly increasing false positives. PEF's detection sensitivity is also shown to be independent of breast density, suggesting that PEF could be a potential tool for detecting breast cancer in young women and women with dense breasts.


Assuntos
Neoplasias da Mama/diagnóstico , Palpação/instrumentação , Palpação/métodos , Feminino , Humanos
12.
J Nanosci Nanotechnol ; 15(4): 3239-43, 2015 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-26353570

RESUMO

We have developed boiling emulsifier-free emulsion polymerization recipes for the synthesis of monodisperse polystyrene (PS) nanospheres with diameters between ca. 100 and 300 nm. The morphologies of the nanospheres during growth were characterized and the results showed that the PS nanospheres with uniform structures could be synthesized rapidly by modifying the reaction conditions. These nanospheres readily self-assemble into three-dimensionally colloidal photonic crystal film and whose photonic band-stop could be tuned over the entire visible spectral region by altering the sphere diameters.

13.
Analyst ; 140(5): 1590-8, 2015 Mar 07.
Artigo em Inglês | MEDLINE | ID: mdl-25599103

RESUMO

We have examined in situ detection of hepatitis B virus 1762T/1764A double mutation (HBVDM) in urine using a (Pb(Mg(1/3)Nb(2/3))O3)(0.65)(PbTiO3)(0.35) (PMN-PT) piezoelectric plate sensor (PEPS) coated with a 16-nucleotide (nt) probe DNA (pDNA) complementary to the HBVDM. The in situ mutation (MT) detection was carried out in a flow with the PEPS vertically situated at the center of the flow in a background of wild type (WT). For validation, this detection was followed by detection in the mixture of MT fluorescent reporter microspheres (FRMs) (MT FRMs) and WT FRMs that emitted different fluorescence colours and were designed to specifically bind to MT and WT, respectively. At 30 °C and 4 ml min(-1), a PEPS was shown to specifically detect HBVDM in situ with 60 copies ml(-1) analytical sensitivity in a background of clinically-relevant 250-fold more WT in 30 min without DNA isolation, amplification, or labelling as validated by the visualization of the captured MT FRMs and WT FRMs following FRM detection where the captured MT FRMs outnumbered the WT FRMs by a factor of 5 to 1.


Assuntos
Técnicas Biossensoriais/métodos , Análise Mutacional de DNA/métodos , DNA Viral/urina , Vírus da Hepatite B/isolamento & purificação , Hepatite B/diagnóstico , Mutação/genética , DNA Viral/genética , Fluorescência , Genótipo , Hepatite B/genética , Hepatite B/virologia , Vírus da Hepatite B/genética , Humanos , Microesferas , Reação em Cadeia da Polimerase
14.
Analyst ; 139(11): 2754-63, 2014 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-24759937

RESUMO

We have examined real-time, in situ hybridization detection of target DNA (tDNA) in a buffer solution and in urine using 8 µm-thick lead magnesium niobate-lead titanate (PMN-PT) piezoelectric plate sensors (PEPSs) about 1.1-1.2 mm long and 0.45 mm wide with improved 3-mercaptopropyltrimethoxysilane (MPS) insulation and a new multiple-parabola (>50) resonance peak position fitting algorithm. With probe DNA (pDNA) immobilized on the PEPS surface and by monitoring the first width extension mode (WEM) resonance frequency shift we detected tDNA in real time at concentration as low as 1 × 10(-19) M in urine (100 zM) with a signal to noise ratio (SNR) of 13 without DNA isolation and amplification at room temperature in 30 min. The present multiple-parabola fitting algorithm increased the detection of SNR by about 10 times compared to those obtained using the raw data and by about 5 times compared to those obtained using single parabola fitting. The detection was validated by in situ follow-up detection and subsequent visualization of fluorescent reporter microspheres (FRMs) coated with reporter DNA complementary to the tDNA but different from the probe pDNA.


Assuntos
Algoritmos , DNA/genética , Hibridização de Ácido Nucleico , Limite de Detecção , Razão Sinal-Ruído
15.
Biomaterials ; 35(9): 2971-80, 2014 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-24411673

RESUMO

In this study, we examined the use of CdSe aqueous quantum dots (AQDs) each conjugated to three streptavidin as a fluorescent label to image Tn antigen expression in various breast tissues via a sandwich staining procedure where the primary monoclonal anti-Tn antibody was bound to the Tn antigen on the tissue, a biotin-labeled secondary antibody was bound to the primary anti-Tn antibody, and finally the streptavidin-conjugated AQDs were bound to the biotin on the secondary antibody. We evaluated the AQD staining of Tn antigen on tissue microarrays consisting of 395 cores from 115 cases including three tumor cores and one normal-tissue core from each breast cancer case and three tumor cores from each benign case. The results indicated AQD-Tn staining was positive in more than 90% of the cells in the cancer cores but not the cells in the normal-tissue cores and the benign tumor cores. As a result, AQD-Tn staining exhibited 95% sensitivity and 90% specificity in differentiating breast cancer against normal breast tissues and benign breast conditions. These results were better than the 90% sensitivity and 80% specificity exhibited by the corresponding horse radish peroxidase (HRP) staining using the same antibodies on the same tissues and those of previous studies that used different fluorescent labels to image Tn antigen. In addition to sensitivity and specificity, the current AQD-Tn staining with a definitive threshold was quantitative.


Assuntos
Antígenos Glicosídicos Associados a Tumores/metabolismo , Mama/metabolismo , Compostos de Cádmio , Pontos Quânticos , Compostos de Selênio , Análise Serial de Tecidos , Água/química , Mama/patologia , Neoplasias da Mama/diagnóstico , Neoplasias da Mama/patologia , Carcinoma Ductal de Mama/diagnóstico , Carcinoma Ductal de Mama/patologia , Linhagem Celular Tumoral , Feminino , Fluorescência , Imunofluorescência , Peroxidase do Rábano Silvestre/metabolismo , Humanos , Luminescência , Análise Espectral , Coloração e Rotulagem
16.
Analyst ; 138(24): 7316-25, 2013 Nov 12.
Artigo em Inglês | MEDLINE | ID: mdl-24151632

RESUMO

Quantum dots (QDs) are photoluminescent nanoparticles that can be directly or indirectly coupled with a receptor such as an antibody to specifically image a target biomolecule such as an antigen. Recent studies have shown that QDs can be directly made at room temperature and in an aqueous environment (AQDs) with 3-mercaptopropionic acid (MPA) as the capping ligand without solvent and ligand exchange typically required by QDs made by the organic solvent routes (OQDs). In this study, we have synthesized CdSe AQDs and compared their conjugation efficiency and imaging efficacy with commercial carboxylated OQDs in HT29 colon cancer cells using a primary antibody-biotinylated secondary antibody-streptavidin (SA) sandwich. We showed that the best imaging condition for AQDs occurred when one AQD was bound with 3 ± 0.3 SA with a nominal SA/AQD ratio of 4 corresponding to an SA conjugation efficiency of 75 ± 7.5%. In comparison, for commercial CdSe-ZnS OQDs to achieve 2.7 ± 0.4 bound SAs per OQD for comparable imaging efficacy a nominal SA/OQD ratio of 80 was needed corresponding to an SA conjugation efficiency of 3.4 ± 0.5% for CdSe-ZnS OQDs. The more than 10 times better SA conjugation efficiency of the CdSe AQDs as compared to that of the CdSe-ZnS OQDs was attributed to more capping molecules on the AQD surface as a result of the direct aqueous synthesis. More capping molecules on the AQD surface also allowed the SA-AQD conjugate to be stable in cell culture medium for more than three days without losing their staining capability in a flowing cell culture medium. In contrast, SA-OQD conjugates aggregated in cell culture medium and in phosphate buffer saline solution over time.

17.
Analyst ; 138(20): 6117-26, 2013 Oct 21.
Artigo em Inglês | MEDLINE | ID: mdl-23964355

RESUMO

Detection of mutated (MT) deoxyribonucleic acid (DNA) amongst the wild type (WT) requires the probe DNA (pDNA) that is complementary to the MT to discriminate the WT by one or two nucleotide mismatches. Traditionally this is achieved by raising the temperature to above the melting temperature (Tm) of the WT (TWT) but below that of the MT (TMT). However, a raised temperature is also accompanied by a weakened binding of the MT to the pDNA which can reduce the detection sensitivity. In this study, we investigated flow as a way to enhance MT detection specificity at a lower temperature. Gold-coated glass (GCG) slides immobilized with pDNA complementary to the target MT were placed at the center of the flow cell. The detection was done by flowing MT or WT at various concentrations followed by flowing 10(5) ml(-1) fluorescent reporter microspheres (FRMs) that were 6 µm in size and coated with reporter DNA complementary to the MT or WT but different from the pDNA at various flow rates and temperatures. The detection of MT or WT was characterized by counting the FRMs captured on the GCG. Hepatitis B virus 1762/1764 double mutation (HBV DM) was the model MT and the TMT and TWT were 47 °C and 22 °C, respectively. It was shown that at room temperature, flow initially increased the binding of both the MT and WT at lower flow rates but decreased the binding at flow rates ≥4 ml min(-1) due to the increase in the flow-induced impingement force on the FRMs to overcome the binding of the MT and the WT to the GCG at higher flow rates. At ≥30 °C the decrease in binding of the WT with an increasing flow rate was more than that of the MT because 30 °C was above the TWT but still well below the TMT. As a result, the detection of MT at 30 °C with a flow rate of 4 ml min(-1) was more specific than at 35 °C without flow. These results indicate that flow can diminish WT binding at a lower temperature than without flow and allow MT detection to occur at a lower temperature with high specificity.


Assuntos
DNA/análise , DNA/genética , Ambiente Controlado , Genes Reporter/genética , Microesferas , Mutação/genética , Temperatura Ambiente , Vírus da Hepatite B/química , Vírus da Hepatite B/genética
18.
J Am Coll Surg ; 216(6): 1168-73, 2013 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-23623223

RESUMO

BACKGROUND: Mammography is key to detection of breast cancer in high-risk populations. Currently, aside from palpation and risk-assessment questionnaires, there is no prescreening test that can improve the accuracy, safety, and cost effectiveness of screening low-risk populations. The piezoelectric finger (PEF) is a radiation-free, portable, and low-cost breast tumor detector we developed to be used as a prescreening tool. STUDY DESIGN: Patients presenting with breast abnormalities detected by palpation or imaging were enrolled in this IRB-approved study. The PEF testing was performed with the patient in supine position before undergoing biopsy or surgical excision. The locations of the lesions detected by PEF were compared with those confirmed on imaging or pathology. RESULTS: A total of 40 patients were enrolled and 46 lesions were confirmed by imaging or pathology. The PEF reported 55 lesions, with 9 false positives and 2 true positives not originally found on imaging or palpation. The overall sensitivity of the PEF test was 87% (40 of 46). In women 40 years old or younger, overall sensitivity was or 100% (19 of 19). In women who had a lesion visible on mammography, PEF had a sensitivity of 83% (24 of 29). Of these, in women aged 40 years or younger, PEF identified all 7 mammographically visible lesions, including 2 malignant lesions. When compared with ultrasound, PEF correctly identified 87% (34 of 39) in this group. Of these, in women aged 40 years or younger, PEF identified 100% (19 of 19) of all ultrasound-visible lesions. CONCLUSIONS: The PEF identified abnormalities in all 39 patients who presented with breast abnormalities and did not demonstrate any false negatives that would prevent the patients from additional evaluation, which makes it a good prescreening tool. In addition, PEF demonstrated 100% sensitivity in women aged 40 years or younger, a traditionally low-risk population.


Assuntos
Neoplasias da Mama/diagnóstico , Palpação/instrumentação , Ultrassonografia Mamária/instrumentação , Adulto , Idoso , Diagnóstico Diferencial , Desenho de Equipamento , Feminino , Seguimentos , Humanos , Pessoa de Meia-Idade , Estudos Prospectivos , Reprodutibilidade dos Testes , Adulto Jovem
19.
Biosens Bioelectron ; 43: 391-9, 2013 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-23356996

RESUMO

In this paper we have investigated real-time, in situ DNA hybridization detection using piezoelectric plate sensors (PEPSs) consisting of a highly piezoelectric lead magnesium niobate-lead titanate (PMN-PT) layer 8µm in thickness thinly coated with Cr/Au electrodes and electrically insulated with 3-mercaptopropyltrimethoxysilane (MPS) encapsulation. With probe complementary DNA (cDNA) immobilized on the PEPS surface and by monitoring the first longitudinal extension mode (LEM) resonance frequency shift of the PEPS we detected hybridization of the target DNA (tDNA) to the probe cDNA on the PEPS surface in real time at concentration 1.6×10(-18)M with a signal to noise ratio of 8 without isolation and amplification at room temperature in 30min in phosphate buffered saline (PBS) solution. The detection was validated in situ by two different methods: (1) the detection of fluorescently labeled microspheres coated with reporter cDNA complementary to the tDNA but different from the probe cDNA; (2) fluorescent visualization.


Assuntos
Técnicas Biossensoriais/instrumentação , DNA/genética , Hibridização In Situ/instrumentação , Sistemas Microeletromecânicos/instrumentação , Sistemas de Computação , Desenho de Equipamento , Análise de Falha de Equipamento , Técnicas de Amplificação de Ácido Nucleico , Sensibilidade e Especificidade
20.
J Appl Phys ; 112(10): 104506, 2012 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-23258941

RESUMO

Converting ambient thermal energy into electricity is of great interest in harvesting energy from the environment. Piezoelectric cantilevers have previously been shown to be an effective biosensor and a tool for elasticity mapping. Here we show that a single piezoelectric (lead-zirconate titanate (PZT)) layer cantilever can be used to convert heat to electricity through pyroelectric effect. Furthermore, piezoelectric-metal (PZT-Ti) bi-layer cantilever showed an enhanced induced voltage over the single PZT layer alone due to the additional piezoelectric effect. This type of device can be a way for converting heat energy into electricity.

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