Molecularly Imprinted Silver‐Halide Reflection Holograms for Label‐Free Opto‐Chemical Sensing

Hierarchical structuring of materials offers exciting opportunities to construct functional devices that exploit the ordering at different length scales to impart key functional properties. Herein, multiple processes are combined to create complex materials organized at the molecular, nano, and microscales for selective detection of testosterone by label‐free opto‐chemical sensing. Molecular imprinting is used to construct molecular scale analyte‐selective cavities. Microphase separation produces a porous polymer film within which sensitized silver halide nanocolloids are dispersed by a process of infusion and controled precipitation, then converted to periodic layers of silver nanoparticles by holographic patterning followed by chemical development. Testosterone binding is followed via wavelength changes of the holographic reflection peak as a function of testosterone concentration and incubation time. Polymer cross‐linking and film porosity are optimized with respect to the needs of both molecular recognition and hologram quality. The silver halide infusion step does not destroy the molecular selectivity of the molecularly imprinted polymers (MIP). Selective, label‐free sensing of testosterone is possible at concentrations down to 1 μm . The approach is generic and should be applicable to many types of molecules and conventional MIP formulations, individually or in multiplexed arrays.     

Nanosphere Lithography as a Versatile Method to Generate Surface‐Imprinted Polymer Films for Selective Protein Recognition

A versatile approach based on nanosphere lithography is proposed to generate surface‐imprinted polymers for selective protein recognition. A layer of 750 nm diameter latex bead‐protein conjugate is deposited onto the surface of gold‐coated quartz crystals followed by the electrosynthesis of a poly(3,4‐ethylenedioxythiophene)/poly(styrenesulfonate) (PEDOT/PSS) film with thicknesses on the order of the bead radius. The removal of the polymer bead‐protein conjugates, facilitated by using a cleavable protein‐nanosphere linkage is shown to result in 2D arrays of periodic complementary size cavities. Here it is demonstrated by nanogravimetric measurements that the imprinting proceeds further at molecular level and the protein (avidin) coating of the beads generates selective recognition sites for avidin on the surface of the PEDOT/PSS film. The binding capacity of such surface‐imprinted polymer films is ca. 6.5 times higher than that of films imprinted with unmodified beads. They also exhibit excellent selectivity against analogues of avidin, i.e., extravidin, streptavidin, and neutravidin, the latter being in fact undetectable. This methodology, if coupled with properly oriented conjugation of the macromolecular template to the nanoparticles, offers the possibility of site‐directed imprinting.     

Molecularly Imprinted Polymers and Electrospinning: Manufacturing Convergence for Next‐Level Applications

Micro‐ and especially nanofiber‐type of materials are extremely attractive for a number of applications, ranging from separation and analysis to drug delivery and tissue engineering, and the majority of them are currently produced worldwide via the extremely popular and effective electrospinning technique. The addition of specific tailored molecular recognition capability to these electrospun materials via the established molecular imprinting technology can be extremely beneficial for a number of applications, as indicated by the number of examples in the literature over the past 15 years. However, the integration of these two technologies has proven to be quite challenging, mainly due to the different processing methodologies which characterize the two approaches. In this progress report, the practical difficulties related to the combination of electrospinning and molecular imprinting and to the production of molecularly imprinted electrospun fibers are addressed, discussing the main aspects to take into consideration when designing and optimizing the experimental protocols, as well as highlighting the most prolific research applications that have been explored thus far, to conclude with a commercial/industrial and economic perspective on the envisaged market for these hybrid products.     

AFM观察ACh和PAS抑制剂对AChE四聚体结构的影响

目的:探索乙酰胆碱(ACh)和外周阴离子部位(PAS)在调节乙酰胆碱酯酶四聚体(AChE G4)结构中的作用.方法:冰浴超声法制备磷脂膜,囊泡融合技术将AChE G4重组到以云母为支撑的磷脂膜上,原子力显微技术(AFM)观察与ACh或propidium(PAS抑制剂)-ACh作用前后AChE G4的亚分子结构变化.结果:天然AChE G4的各个亚基排列紧密,未见亚基构成.ACh时重组在以云母为支撑人工磷脂膜上的AChE G4(蛋白处于近生理条件下,非晶体状态)亚分子结构最明显的影响是亚基排列松散,亚基之间形成一个无阻碍空间即在四聚体的中间形成一个中央通道,中央通道依次经小→大→小→侧门变化;而在PAS抑制剂存在时,ACh不引起AChE G4亚分子结构变化.结论:底物ACh引起AChE G4亚分子结构的变化与其水解底物的高效性是一致的,AFM从形态学上证明了在底物ACh作用下AChE G4分子中间形成中央通道可能控制着酶的周转速度.ACh与PAS的相互作用控制着AChE G4中央通道的产生及单个亚基活性中心狭隙的开放,PAS抑制剂可阻断这种作用.     

分子印迹聚合物敏感材料电化学传感器的进展

在介绍分子印迹聚合物材料的基础上,对以分子印迹聚合物作为敏感材料的电化学传感器研究进展进行了论述。着重对电导型、电容型、电流型和电位型等四种类型的工作原理、传感器设计、性能和应用,进行了讨论与评述,并对今后该领域的发展趋势进行了展望。     

Preparation and Characterization of Molecularly Imprinted Polymeric Nanoparticles for Atrial Natriuretic Peptide (ANP)

Natriuretic peptide receptor A (NPRA), the receptor for the cardiac hormone atrial natriuretic peptide (ANP), is expressed abundantly on cancer cells and disruption of ANP‐NPRA signaling inhibits tumor burden and metastasis. Since antagonists of NPRA signaling have not provided reproducible results, we reason that a synthetic neutralizing antibody to ANP, which has high selectivity and affinity for ANP, can be used to regulate ANP levels and attenuate NPRA signaling. In this study, we prepare molecularly imprinted polymeric nanoparticles (MIPNPs) for ANP using a short peptide of ANP as the template and determine their binding affinity and selectivity. The MIPNPs are prepared by precipitation polymerization using NH₂–SLRRSS–CONH₂, which is a short peptide from ANP, as a template, methacrylic acid and N‐isopropylacrylamide as functional monomers, and bis‐acrylamide as a crosslinker. The average diameters of the MIPNPs and of non‐imprinted nanoparticles (NIPNPs) in water are 215.8 ± 4.6 nm and 197.7 ± 3.1 nm respectively. The binding‐isotherm analysis shows that the MIPNPs have a much‐higher binding affinity for the template peptide and ANP than the NIPNPs. Scatchard analysis gives an equilibrium dissociation constant, K_d, of 7.3 × 10^?6 M with a binding capacity of 106.7 μmol g^?1 for the template peptide and a K_d of 7.9 × 10^?6 M with a binding capacity of 36.0 μmol g^?1 for the ANP. Measurements of the binding kinetics reveal that MIPNPs reach protein‐adsorption equilibrium in 30 min. The MIPNPs are found to have a high specificity for ANP with little affinity for BSA or scrambled ANP peptide. The MIPNPs also recognize and adsorb ANP in cell‐culture medium spiked with ANP and in human plasma. Taken together, these results indicate that the MIPNPs have a high affinity and selectivity for ANP and can be used as a synthetic antibody for modulating ANP‐NPRA signaling in cancers.     

Selective Artificial Receptors Based on Micropatterned Surface‐Imprinted Polymers for Label‐Free Detection of Proteins by SPR Imaging

A novel concept to generate micropatterned surface‐imprinted polymers (SIPs) for protein recognition by using standard photolithographic technology is introduced. Avidin‐imprinted poly(3,4‐ethylenedioxythiophene)/poly(styrenesulfonate) (PEDOT/PSS) conducting polymer microbands are prepared directly on surface plasmon resonance (SPR) chips, which enable convenient label‐free monitoring of the binding events. The novel surface‐imprinted microstructures bind avidin, the template protein, with dissociation constants in the submicromolar range (125 nM ). The SIPs have an avidin binding capacity approximately one order of magnitude higher than the corresponding nonimprinted polymers and are able to discriminate among functional homologues of avidin, i.e., neutravidin, extravidin, and streptavidin.     

Hybrid Organic‐Inorganic Biosensor for Ammonia Operating under Harsh Physiological Conditions

A biosensor for ammonia is developed aimed at detecting the presence of H. pylori bacteria in gastric fluids. The sensor is based on a GaAs device coated with a unique functional polymer that enables high device sensitivity to low concentrations of ammonia and long‐term protection in harsh environments. The detection of ammonia in gastric fluids taken from patients is possible by covering the device with a dialysis membrane, thus enabling the diffusion of only small molecules to the sensing area, while preventing agglomeration of macromolecules on the surface of the device. The mechanism by which ammonia is detected is investigated and an analytical expression is provided relating the response of the detector to the ammonia concentration and the pH of the solution.     

Handwriting Character Recognition Based on Conductor/Insulator-Identifiable E-Tattoo Proximity Sensors for Blinds

Easy and convenient reading for blinds is of great significance for lowering their learning, entertainment, and communication barrier, and improving their living quality. The general solution is to learn braille, far from satisfying the meet of the blinds’ daily learning and communication. Here, a new-type conductor/insulator-identifiable e-tattoo proximity sensor is developed by simply depositing the circular interdigitated electrodes on organic semiconductor. The discriminable recognition toward conductors and insulators is realized only based on a single e-tattoo device. The sensors not only enable recognition of the protruding characters like braille based on distance difference, but also enable recognition of the handwriting ink-brush and pencil graphite characters based on the unique advantage of the sensors in distinguishing conduct and insulator. These results open a new route to realize the material category recognition, provide a user-friendly way to help the visual impaired effectively reintegrate into society, and broaden the application field of proximity sensors.     

粒子群优化和拉凡格氏混合优化算法提取传感布里渊散射谱特征的方法

在基于布里渊散射的分布式光纤传感系统中,沿途光电检测信号信噪比(SNR)过低为被测量的信息反演带来困难。针对高精度解调传感布里渊散射谱的布里渊频偏量的需求,提出了一种利用粒子群优化(PSO)和拉凡格氏(L-M)混合优化算法对传感散射谱进行特征提取的方法。利用PSO算法粗调得到一组全局最优解,再以全局最优解作为L-M算法的初值,最终将L-M算法的运算结果作为结果输出。它克服了PSO算法过早收敛于局部极值和L-M算法依赖初值的问题,保证了求解的速度和精度。数值分析表明,新算法适合对不同权重比、不同线宽和低SNR、大测量范围情况下的散射谱进行参数估计,并且在SNR为10dB的情况下得到的绝对误差仅为2.18838MHz,优于其他两种算法。实验研究表明新算法适用于多种脉宽状况下的布里渊散射谱的特征提取,并可有效提高预测精度。     

用于手写体数字识别的视觉与神经网络混合算法

本文提出了用于无约束手写体数字特征提取和识别的视觉与神经网络混合算法。为了提高不变性特征的稳定性及网络收敛速度,我们引入周期包括函数来取代传统的sigmoid激活函数,计算机模拟结果显示该算法及激活函数能有效地提取手写体不变性特征,提高网络收敛速度和识别率。     

基于分形编码和奇异值分解的混合人脸识别方法

该文提出了一种新的基于分形编码的人脸识别方法。在分形近邻距离的基础上,提出了分形奇异值近邻距离,并把分形编码和局部奇异值分解结合起来,提高了识别率。实验结果表明,与仅仅使用分形近邻距离相比,该算法对光照变化、表情和姿态变化具有更大的容忍度,而且训练时间短,识别率高。     

基于光电混合功率谱分析的BP神经网络分类器在癌细胞筛选中的应用

基于光电混合功率谱分析的ＢＰ神经网络分类器在癌细胞筛选中的应用张以谟，史韦，李贺桥（天津大学现代光学仪器研究所）ＡｎＡｐｐｌｉｃａｔｉｏｎｏｆＢＰＮｅｕｒａｌＮｅｔｗｏｒｋｆｏｒＣａｎｃｅｒＣｅｌｌＰａｔｔｅｒｎＲｅｃｏｇｎｉｔｉｏｎＢａｓｅｄｏｎｔ...     

A Hybrid Approach‐Based Sparse Gaussian Kernel Model for Vehicle State Determination during Outage‐Free and Complete‐Outage GPS Periods

To improve the ability to determine a vehicle's movement information even in a challenging environment, a hybrid approach called non‐Gaussian square root‐unscented particle filtering (nGSR‐UPF) is presented. This approach combines a square root‐unscented Kalman filter (SR‐UKF) and a particle filter (PF) to determinate the vehicle state where measurement noises are taken as a finite Gaussian kernel mixture and are approximated using a sparse Gaussian kernel density estimation method. During an outage‐free GPS period, the updated mean and covariance, computed using SR‐UKF, are estimated based on a GPS observation update. During a complete GPS outage, nGSR‐UPF operates in prediction mode. Indeed, because the inertial sensors used suffer from a large drift in this case, SR‐UKF‐based importance density is then responsible for shifting the weighted particles toward the high‐likelihood regions to improve the accuracy of the vehicle state. The proposed method is compared with some existing estimation methods and the experiment results prove that nGSR‐UPF is the most accurate during both outage‐free and complete‐outage GPS periods.