基于GMR传感器阵列的生物检测研究

利用磁性传感器,特别是GMR传感器,对生物特异性反应进行检测,从而解决传统荧光检测存在的标记易失、可重复性差,对设备和技术人员要求高等缺点.采用超顺磁磁珠作为磁性标记物,将其与被测生物分子充分结合后固定在芯片表面,再通过磁阻传感器的磁阻变化检测磁性标记的存在.采用高灵敏度的GMR传感器和磁性含量高的磁性颗粒,减小标记与传感器之间的距离和尺度差异,能提高阵列生物检测性能.将GMR传感器阵列应用在生物检测上是极具发展前途的研究方向,通过对已有方案的改良或选用新型的材料,最终会实现磁性生物传感器灵敏、快速、便捷的实际应用.     

基于GMR生物传感器的甲胎蛋白检测

采用磁控溅射、光刻、离子束刻蚀和剥离工艺等工艺和方法,制备了多层膜结构的巨磁阻(GMR)生物传感器件,并利用此种传感器来检测甲胎蛋白。在传感器表面通过生物处理固定甲胎蛋白单克隆抗体(McAb1)作为探针,以捕获目标抗原———甲胎蛋白。用直径1μm的超顺磁磁珠标记目标抗原。当传感器表面抗体将目标抗原捕获后,磁珠标记即被固定在GMR传感器的表面。垂直于传感器表面施加230 Oe(1 Am-1=4π×10-3 Oe)的磁场,即可检测到由磁珠产生的信号。本实验对质量浓度为1 ng/mL的甲胎蛋白进行了检测,得到了信号为0.29～0.34Ω的电阻变化值。此种检测方法可用于诊断原发性肝癌。     

基于MEMS微镜的光栅波导角度调制生物传感器设计与研究

免标记、实时、高灵敏的生物检测是分析生物领域重要的技术。利用光波导模式理论构建生物传感器模型,设计了基于MEMS微镜的小型化生物传感检测系统,测试并分析了MEMS微镜的动态响应特性。通过计算仿真,得到了灵敏度与波导厚度和有效折射率之间的关系。以TE模式和TM模式进行葡萄糖溶液检测,实验结果表明,溶液浓度与入射角间呈现出良好的线性关系,灵敏度可达到5 ng/m L,相比传统的免疫学检测方法具有较高灵敏度。该方法由于检测系统体积小、结构简单、无标记,可实现原位检测,避免了对蛋白质活性的破坏,是一种具有较大潜力的蛋白质无标记光学检测方法。     

基于光栅波导共振耦合的传感器特性研究

该文设计了一种基于光栅波导共振角耦合的生物传感器,通过光栅波导模式谱变化检测传感器表面有效折射率变化的方式,实现了传感器表面附着物的精确检测。并在平板介质光波导理论基础上,推导了三、四层结构理论模型,实验得到了入射角与检测溶液折射率及入射角与分子膜层厚度间的变化关系。结果表明,光栅波导共振角耦合生物传感器入射角与待测溶液折射率存在良好的线性关系,并具有较高灵敏度,精度可达0.01(°)/nm。通过该方法制作出无标记的生物传感器,能广泛应用于生物分子检测,尤其适合蛋白质分子生物检测。     

基于DNA适配体的荧光生物传感器

近年来，随着DNA纳米技术的飞速发展，基于DNA作为适配体的荧光生物传感器不断被大量学者研究和构建，以实现对靶标物质的灵敏快速检测。作为DNA纳米技术的新兴方向，基于DNA适配体的荧光生物传感器具有巨大的应用潜力。该文对近年来基于DNA适配体所构建的荧光生物传感器进行了总结。包括荧光信号的实现:荧光染料标记；非荧光染料标记。荧光检测信号的提升:酶介导的靶标循环和信号扩增策略；链置换反应介导的靶标循环和信号扩增策略；基于链置换反应和酶介导的靶标循环和信号扩增策略。在此基础上对基于DNA适配体的荧光生物传感器进行展望并提出建议。     

临床医学中石英晶体微天平生物传感器的应用研究

石英晶体微天平生物传感器具有检测成本低、操作简单、检测速度快、无需标记、特异度和灵敏度高、可简单再生等优点。近年来,已广泛应用于临床医学中细菌、病毒、衣原体、寄生虫、体液物质的检测,白血病表型的诊断和药物开发等方面。     

新型核酸检测生物传感器研发成功

近日从中科院广州生物医药与健康研究院获悉,该院曾令文团队成功开发出一种基于核酸等温链置换反应技术与胶体金技术的核酸检测生物传感器。该生物传感器具有三个特点：简单快速,检测结果30分钟可以得到,无需复杂的检测仪器,仅需恒温42摄氏度;灵敏度高,检测最低限可达0．01fM（可用于检测低滴度的病毒感染）;     

基于单模光纤传输的单模-无心-单模光纤型表面等离子体共振传感器（特邀）

光纤表面等离子体共振(SPR)传感器结合了光纤传感器的微型化、可在线传输、易操作和SPR生物检测技术的高灵敏、高选择性、免标记等优势,是当前免疫学生物传感器的研究热点。但传统多模光纤SPR传感器的信号在远距离传输中易损耗、失真。文中提出了一种单模-无心-单模光纤型SPR传感器,能有效减小信号传输中的损耗与失真,且适合与当前的光纤网络衔接。为了消除传感器中的干扰信号,改变无心光纤的芯径,采用去除背景干扰,高斯拟合等方法,最终选取了具有芯径为61.5 μm无心光纤的此类传感器,并从中提取出了有效的SPR光谱信号。传感器的灵敏度为1153.40 nm/RIU,分辨率为1.70×10?4 RIU。此类光纤生物传感器的成功开发,为智慧医疗、远程医疗提供了一种新的思路。     

基于光纤维生物传感器的研究

光与生物有着密切的联系,光是一种电磁波,光的传播速度是300000000米每秒。光与生物学之间的关系可以概括为:生物发光反应;光在生物物质中的能量传递,譬如生物物质的光吸收、光猝灭和受光激发等。生物反应物质对光的传播影响。随着高科技的发展,已经研制出光纤维生物传感器,光纤维生物传感器主要有光学器件检测光的灵敏度非常高,当然那用光纤维制成的生物传感器灵敏度也非常的高。另外,光信号的传播不受外界电磁波的干扰,传感器的噪声低。光纤生物传感器指用光导纤维及其检测器与生物分子识别器组装构成生物传感器。     

巨磁阻抗传感器在生物检测领域的研究进展

对巨磁阻抗(GMI)效应的产生以及基于GMI效应制备的生物传感器的优势进行了简单阐述,分析了GMI生物传感器应用于生物检测的工作原理,并对GMI生物传感器的制备方法以及主要的薄膜结构对GMI比值的影响进行了综合介绍,总结了GMI生物传感器在生物检测中的应用,并重点阐述了GMI生物传感器在免疫磁珠、肿瘤标志物、细菌、病毒...     

Thin-core fiber-optic biosensor for DNA hybridization detection

A real-time label-free DNA biosensor based on thin-core fiber (TCF) interferometer is demonstrated experimentally. The proposed biosensor is constructed by splicing a TCF between two segments of single mode fibers (SMFs) and integrated into a microfluidic channel. By modifying the TCF surface with monolayer poly-l-lysine (PLL) and single-stranded deoxyribonucleic acid (ssDNA) probes, the target DNA molecules can be captured in the microfluidic channel. The transmission spectra of the biosensor are measured and theoretically analyzed under different biosensing reaction processes. The results show that the wavelength has a blue-shift with the process of the DNA hybridization. Due to the advantages of low cost, simple operation as well as good detection effect on DNA molecules hybridization, the proposed biosensor has great application prospects in the fields of gene sequencing, medical diagnosis, cancer detection and environmental engineering.     

Nondestructive characterization of Hg1−xCdxTe layers with n-p structures by magneto-thermoelectric measurements

The thermoelectric properties of n-type Hg_0.79Cd_0.21Te (MCT) and of MCT layers with n-p structure have been investigated in transverse (B ⊥ ∇T) and longitudinal (B ‖∇T) magnetic fields (0 ≤ B ≤ 16 kG) using the lateral gradient method at temperatures between 10 and 300K. The experimental results were analyzed by considering the contributions of electrons and holes to the magneto-thermoelectric effect and the scattering mechanisms involved. The analysis is based on a nonparabolic conduction band and Landau quantization as well as empirical relations for the band gap, the intrinsic carrier density, and the magnetoresistance. For n-type MCT at low temperatures (10 < T < 30K) and weak magnetic fields (B < 2 kG), the transverse magneto-thermoelectric effect (TME) was seen to be dominated by electron scattering on ionized defects. Longitudinal acoustic phonon drag was found to affect the TME in strong magnetic fields (B > 3 kG) at low temperatures (T < 20K). Longitudinal (LO) phonons were shown to prevail in the electron scattering at higher temperatures (T > 50K) in weak magnetic fields. With increasing magnetic fields, the effect of LO-phonon scattering decreases, and eventually the TME becomes independent of electron scattering. The longitudinal magneto-thermoelectric effect of n-type MCT was also found to exhibit magnetophonon oscillations due to LO-phonon scattering from both HgTe and CdTe phonons. The transverse magnetoresistance (TMR) of the n-type layers in the quantum region has been found to be linearly dependent on the magnetic field. Owing to the TMR of the n-type layers, the variation of the TME of p-n multiple layers with magnetic field is much larger than the variation of the Seebeck coefficient with temperature. Thus, the sensitivity to p-type layers is considerably enhanced compared to that of the Seebeck coefficient. As a result, the TME has proved to be particularly useful in determining the doping and composition of the constituent layers of MCT n-p structures.     

The effect of pH and DNA concentration on organic thin-film transistor biosensors

Organic electronics are beginning to attract more interest for biosensor technology as they provide an amenable interface between biology and electronics. Stable biosensor based on electronic detection platform would represent a significant advancement in technology as costs and analysis time would decrease immensely. Organic materials provide a route toward that goal due to their compatibility with electronic applications and biological molecules. In this report, we detail the effects of experimental parameters, such as pH and concentration, toward the selective detection of DNA via surface-bound peptide nucleic acid (PNA) sequences on organic transistor biosensors. The OTFT biosensors are fabricated with thin-films of the organic semiconductor, 5,5′-bis-(7-dodecyl-9H-fluoren-2-yl)-2,2′-bithiophene (DDFTTF), in which they exhibit a stable mobility of 0.2 cm² V⁻¹ s⁻¹ in buffer solutions (phosphate-buffer saline, pH 7.4 or sodium acetate, pH 7). Device performance were optimized to minimize the deleterious effects of pH on gate-bias stress such that the sensitivity toward DNA detection can be improved. In titration experiments, the surface-bound PNA probes were saturated with 50 nM of complementary target DNA, which required a 10-fold increase in concentration of single-base mismatched target DNA to achieve a similar surface saturation. The binding constant of DNA on the surface-bound PNA probes was determined from the concentration-dependent response (titration measurements) of our organic transistor biosensors.     

Artificial Intelligence-Assisted Label-Free Spectroscopic Quantification of Global DNA Cytosine Methylation in a Miniature Plasmonic Pickering Emulsion

Epigenetic DNA methylations are early and frequently observed events in a diversity of diseases such as cancer. Despite the considerable clinical values for cancer liquid biopsy, quantitative analysis of DNA methylations remains a major challenge due to the lack of rapid, sensitive detection techniques. Here, an artificial intelligence-assisted label-free surface-enhanced Raman spectroscopy (SERS) (iMeSERS) biosensor is reported for simultaneous quantification of C⁵-methylcytosine (^5mC) level and methylation ratio in DNA samples. This method utilizes the plasmonic Pickering emulsions as the biosensing platform for label-free SERS detection, formed upon the addition of a sub-microliter DNA sample to the hydrophobic Au nanostar-containing n-decane. Distinct spectral signatures of monophosphates of canonical deoxyribonucleotides (dNMPs) and the common methylation modification 5-methyl-2′-deoxycytidine (d^5mCMP) are identified and distinguished by the iMeSERS biosensor. The deep learning algorithms trained with SERS signatures of dNMPs and d^5mCMP are then applied to the quantitative analysis of global DNA methylation. The exceptional capability of the deep learning-driven approach is demonstrated for simultaneous quantification of the methylation ratio and level using a sub-microliter volume of DNA samples. This work shows the power of label-free SERS techniques combined with deep learning algorithms for quantitative analysis of epigenetic DNA modifications with great promises for clinical diagnosis.     

Numerical simulation of the position and orientation effects on the impedance response of nanoelectrode array biosensors to DNA and PNA strands

This paper investigates by simulation the response of a nanoelectrode capacitive biosensor to single and double strands of DNA/PNA and up to frequencies well above the electrolyte dielectric relaxation limit. The expected change in capacitance both for an idealized two electrodes system with 2D cylindrical symmetry and a complex nanoelectrode array, where the biomolecule is represented by a dielectric and charged rod, is calculated for different positions and orientations of the strand. DNA and PNA hybridization is also considered. The results provide indications on optimum detection conditions for admittance based DNA biosensors.     

A localized surface plasmon resonance DNA biosensor based on gold nanospheres coated on the tip of the fiber

A localized surface plasmon resonance (LSPR) biosensor was prepared with gold nanospheres (AuNSs) coated on the tip face of the optical silica fiber. AuNSs with the sizes of 20 nm and 80 nm were used. The sensitivities of AuNS20 nm and AuNS80 nm modified sensors to bulk refractive index (RI) variation are 82.86 nm/RIU and 218.98 nm/RIU, respectively. The AuNS80 nm modified sensor was used for the detection of 40 bases DNA hybridization and the limit of detection is 50 nmol/L, where the 40-bases DNA probe was covalently linked with AuNS80 nm. The complementary DNA sequence in tris-acetate-EDTA (TAE) buffer solution was detected as the target DNA. This fiber sensor has the advantages of small sample consumption, easy fabrication and high sensitivity.     

基于C型太赫兹超材料的高灵敏度生物传感器

提出了一种基于C型超材料的太赫兹波段高灵敏度透射型生物传感器。利用电磁场软件CST2016对其传感器的特性进行研究。通过改变四个微纳金属结构的旋转角度、微纳金属结构的位置,对其传感器的Q值特性进行了分析,并进一步研究了微流通道的通道高度、覆盖层和基底的介电常数对其传感器灵敏度的影响。研究结果表明,当微纳金属结构旋转角度75°,上下金属结构间位置相对平移3μm,微流通道高度45μm,覆盖层和基底采用相对介电常数为2.25的聚乙烯材料时,设计的C型超材料生物传感器的灵敏度为0.0936 THz/RIU。该传感器在太赫兹波生物医学领域有着广阔的应用前景。     

Optical intensity-based long-period fiber grating biosensors and biomedical applications [Life Sciences]

Biosensors have been extensively studied and applied in various domains, including medical, life science, food processing, environmental monitoring, security, and military applications. Fiber-optic biosensors, a subclass of optical biosensors, have attracted considerable attention because of their unique advantages over their electronic counterparts. Most fiber-based biosensors are commonly targeted for use in routine tests, patient home care, surgery, image-guided therapy, intensive care, and emergency situations where in situ operation and cost-effectiveness are among the most desired features. As a result, a fiber-based biosensor needs to be designed with a simple and fast signal-processing scheme in mind. In this article, we will present a novel long-period fiber grating (LPFG) biosensor that can employ the simple and cost-effective optical intensitybased signal process method instead of the complex and expensive optical spectrum-based method. The ionic self-assembled multilayers (ISAM) technique is utilized to immobilize a thin layer of biorecognition film on the surface of a specially designed turnaround- point (TAP) LPFG. The new sensor maintains the optical resonant feature to achieve the desired high sensitivity but can be interrogated using optical intensity-based signal-processing. The new TAP-LPFG biosensor may be used for real-time DNA forensic analysis.     

GMR生物传感器的原理及研究现状

GMR生物传感器包括三个部分,即免疫磁性微球、高灵敏度GMR传感器以及相关读出电路。与其他生物传感器相比,它具有灵敏度高、分辨力强、价格低、市场普及潜力大、设备小型化及测量过程自动化等优点。综述了GMR生物传感器的研究现状,对相关技术的工作原理进行了分析,提出了GMR生物传感器的应用前景和有待解决的问题。