电致发光细胞传感器及其分析应用

电致发光细胞传感器具有灵敏度高、反应可控性强、背景干扰低、分析实时、对检测对象无损等优点,近年来成为生物分析和临床诊断等领域的研究热点。该文针对电致发光细胞传感器构建以及纳米发光探针的设计介绍其在肿瘤细胞定量分析、肿瘤标志物分析、单细胞分析以及细胞功能分析等方面的应用,并对电致发光技术在细胞传感中的研究趋势进行展望。     

Advanced electrocatalytic materials based biosensors for cancer cell detection – A review

Herein, we have highlighted the latest developments on biosensors for cancer cell detection. Electrochemical (EC) biosensors offer several advantages such as high sensitivity, selectivity, rapid analysis, portability, low-cost, etc. Generally, biosensors could be classified into other basic categories such as immunosensors, aptasensors, cytosensors, electrochemiluminescence (ECL), and photo-electrochemical (PEC) sensors. The significance of the EC biosensors is that they could detect several biomolecules in human body including cholesterol, glucose, lactate, uric acid, DNA, blood ketones, hemoglobin, and others. Recently, various EC biosensors have been developed by using electrocatalytic materials such as silver sulfide (Ag₂S), black phosphene (BPene), hexagonal carbon nitrogen tube (HCNT), carbon dots (CDs)/cobalt oxy-hydroxide (CoOOH), cuprous oxide (Cu₂O), polymer dots (PDs), manganese oxide (MnO₂), graphene derivatives, and gold nanoparticles (Au-NPs). In some cases, these newly developed biosensors could be able to detect cancer cells with a limit of detection (LOD) of 1 cell/mL. In addition, many remaining challenges have to be addressed and validated by testing more real samples and confirm that these EC biosensors are more accurate and reliable to measure cancer cells in the blood and salivary samples.     

光电化学生物分析研究进展

光电化学生物分析是近年来新出现并发展迅速的一种分析技术,其检测原理是基于在光照下识别元件和目标分子之间的生物识别作用造成光电活性物质产生的电信号的改变,以实现对待测物的定量测定。由于其灵敏选择性检测的优点及其在生物分析中的巨大潜力,该方法吸引了较多的关注,并且在检测性能和生物传感应用等方面也取得了较大进步。本文针对光电化学生物分析中常见的四种应用领域,即直接光电化学检测、光电化学酶检测、光电化学核酸检测以及光电化学免疫分析,综述了近年来国内外在光电化学生物分析研究领域的最新进展,并对其未来发展进行了展望。     

Near-infrared Responsive Photoelectrochemical Biosensors

Near-infrared (NIR) light-driven photoelectrochemical (PEC) sensing is a highly promising analytical technique, especially for in situ bioanalysis, due to the deep penetration capability and minimal invasiveness of NIR light. In this mini review, we provide a brief overview of recently developed NIR PEC sensors, focusing on NIR light-responsive materials and the representative applications of this type of PEC sensor. Future perspectives for NIR PEC sensors are also described.     

光电催化用于高附加值化学品合成

化石燃料的过度消耗导致了能源短缺和环境破坏,因此可再生清洁能源的开发已成为当务之急.在众多可再生能源中,太阳能因其环境友好,储量巨大且分布广泛等特点而引起了研究者们的兴趣.光电催化(PEC)是一种能够将可再生太阳能转化为化学能的方法,而最受关注的是通过PEC水分解来获得高附加值的氢能源.欲使PEC系统实现水分解,理论上...     

聚电解质复合物溶解性研究

报道了聚电解质复合物的一种新的溶剂体系———离子表面活性剂剂的水溶液 ,研究了表面活性的用量及结构、温度、外加小分子电解质对复合物溶解性的影响 ,初步探讨了溶解机理 ,通过扫描电镜观察了复合物溶解后在溶液中的形态 .研究表明 ,当复合物与离子表面活性剂定量结合到一定程度时 ,就会使复合物发生溶解 .表面活性剂碳链长度的增加、温度的提高均会对复合物的溶解有不同程度的促进 .加入少量的无机电解质如氯化钠 ,会促进复合物的溶解 ,若氯化钠加入量过多 ,反而不利于复合物的溶解 .复合物的溶解机理被认为是表面活性剂的解离作用和疏水作用二者的协同 .     

A New Signal‐On Photoelectrochemical Biosensor Based on a Graphene/Quantum‐Dot Nanocomposite Amplified by the Dual‐Quenched Effect of Bipyridinium Relay and AuNPs

A new photoelectrochemical (PEC) biosensor was developed by using carboxyl‐functionalized graphene and CdSe nanoparticles. This sensitive interface was then successfully applied to detection of thrombin based on the dual‐quenched effect of PEC nanoparticle, which relied on the electron transfer of a bipyridinium relay and energy transfer of AuNPs. After recognition with an aptamer, the PEC nanoparticle was removed and a signal‐on PEC biosensor was obtained. Moreover, the bio‐barcode technique used in the preparation of PEC nanoparticle could avoid cross‐reaction and enhances the sensitivity. Taking advantages of the various methods mentioned above, the sensitivity could be easily enhanced. In addition, in this work we also investigated graphene that was modified with different functional groups and AuNPs of different particle sizes. Under optimal conditions, a detection limit of 5.9×10^?15 M was achieved. With its simplicity, selectivity, and sensitivity, this strategy shows great promise for the fabrication of highly efficient PEC biosensors.     

Biodegradable poly(ethylene carbonate) nanoparticles as a promising drug delivery system with "stealth" potential

The goal of this study was to investigate the suitability of poly(ethylene carbonate) (PEC) nanoparticles as a novel drug delivery system, fulfilling the requirements for a long circulation time. Particles were obtained with a narrow size distribution and nearly neutral zeta potential. Adsorption studies with human plasma proteins revealed that PEC nanoparticles bind much less proteins in comparison to polystyrene (PS) nanoparticles. Cell experiments with fluorescently labeled PEC showed no uptake of the nanoparticles by macrophages. These novel PEC nanospheres with their unique surface properties are a promising candidate for long circulating drug delivery systems in vivo.     

Photoelectrochemical Detection of L‐Cysteine with a Covalently Grafted ZnTAPc‐Gr‐based Probe

L‐cysteine plays a vital role in organisms, and is an important biomarker for many pathological diseases that seriously affect human health. In the study, a photoelectrochemical (PEC) probe with zinc‐tetramine phthalocyanine covalently grafted to graphene oxide (ZnTAPc‐Gr) was developed for L‐cysteine detection. Graphene oxide (GO) with carboxyl was used to immobilize zinc‐tetramine phthalocyanine (ZnTAPc) with amidogen (a graft structure formed by an amide covalent bond), which could firmly immobilize ZnTAPc, thereby improving the photoelectrochemical performance and stability. L‐cysteine molecule, an electron acceptor, was specifically recognized by the PEC probe, exhibiting a decrease in the photocurrent signal. Under the optimal experimental conditions, the fabricated PEC probe exhibited excellent performance in L‐cysteine analysis within a linear range of 0.25–113 μM and a detection limit of 11.4 nM. The PEC probe showed high sensitivity, selectivity, and stability. The method described herein provides an effective strategy for PEC probe construction for L‐cysteine detection, and can also serve as a promising PEC platform for the analyses of other small molecules.     

Changes in the interaction characteristics of polyelectrolyte complex covered silica surfaces

The adsorption of polyelectrolyte complexes, PEC, made from the cationic poly (diallyldimethylammonium) chloride (PDADMAC) and the anionic maleic acid-co-propene copolymer (MA-P) on a Si-wafer surface has been studied. The application of highly diluted colloidally dispersed PEC solutions led to the deposition of single PEC particles onto the surface of the Si-wafer. The interaction forces of the heterogeneously covered surface were monitored by direct force measurements with an atomic force microscope (AFM) in the force volume mode. On the surface of a single PEC particle drastic changes in the interaction forces were found in comparison with the unmodified Si-wafer: in all force vs. distance curves a strong increase of the adhesion was measured that can be attributed to the formation of electrostatic bonds between the negatively charged Si₃N₄-tip and the cationic excess charge of the PEC. Additionally, the behavior during approach of both surfaces has been distinct: at pH 6.1 we see a long range electrostatic attraction between the tip and the PEC particle. The attraction becomes even stronger at pH 4.1, because of an increased positive net charge. Generally, a heterogeneous surface with a wide variety of interaction features can be created by the adsorption of PEC particles.     

Antitumor efficacy of doxorubicin released from crosslinked nanoparticulate chondroitin sulfate/chitosan polyelectrolyte complexes

It is demonstrated that nanoparticulate PEC with a crosslinked shell sustains DOX release and increases DOX activity against cancer cells. CSMA was synthesized to prepare PEC with chitosan. The double bonds among CSMA were used to form a shell crosslink. The released DOX from DOX-loaded PECs against human cancer KB cells and A549 cells were qualitatively traced by confocal laser scanning microscopy and flow cytometry, and quantitatively measured by capillary electrophoresis. All the results implied the DOX-loaded PEC with a crosslinked shell had the best anti-cancer potency of free DOX and the DOX-loaded PEC prepared from pure chondroitin sulfate and chitosan in both the cell lines.     

Preparation of monomodal polyelectrolyte complex nanoparticles of PDADMAC/poly(maleic acid-alt-alpha-methylstyrene) by consecutive centrifugation

We report on the refinement of anionic and cationic nanoparticles of nonstoichometric polyelectrolyte complexes (PEC) by consecutive centrifugation, which was studied by dynamic light scattering (DLS), atomic force microscopy (AFM), colloid titration and infrared spectroscopy (IR). PEC dispersions were prepared by mixing poly(diallyldimethylammonium chloride) (PDADMAC) and sodium poly(maleic acid-alt-alpha-methylstyrene) (PMA-MS) at the monomolar mixing ratio of n-/n+ = 1.50 (anionic PEC) and 0.66 (cationic PEC), respectively, and the polymer concentration of c(POL) = 0.002 M. The particle size (Rh), titrable charge amount, and IR spectra were determined for both dispersions in the original state, after the first centrifugation and after the second centrifugation. Freshly prepared PEC dispersions contained two different particle sizes: around 10-25 nm (small particles) and around 100 nm (large particles). Consecutive centrifugation of freshly prepared PEC dispersions resulted in the separation of highly charged excess polyelectrolyte (PEL) and small PEC particles from a low charged coacervate phase of the desired larger PEC particles. After the second centrifugation, the coacervate phase of both dispersions PEC-1.50 and PEC-0.66 consisted of monomodal particles sizing around 100 nm. These results were supported by AFM measurements on the respective dispersions deposited on glass plates. PEC-1.50 particles tended to adopt slightly smaller sizes ( approximately 90 nm) in comparison to PEC-0.66 ones (approximately 110 nm). No significant influence of the PDADMAC molecular weight on the particle size was found. IR spectroscopy showed changes in the environment of the carboxylate groups of PMA-MS by consecutive centrifugation. The centrifuged PEC-1.50 dispersions showed remarkable long-term stability over more than a year. The high macroscopic stability of the studied PEC dispersions is presumably due to repulsive electrostatic interparticle interactions and attractive hydrophobic intraparticle interaction. The introduced monomodal PEC particles might be projected as latex analogues or as nanocarriers for drugs and proteins.     

Monomodal polyelectrolyte complex nanoparticles of PDADMAC/Poly(styrenesulfonate): preparation and protein interaction

The binding of the model proteins HSA, LYZ and MYO to PEC nanoparticles is reported. PEC particles were prepared by mixing solutions of PDADMAC either with PSS or PMA-MS, followed by consecutive centrifugation. Monomodal anionic (PEC-1.50) and cationic (PEC-0.66) PEC particles were obtained using non-stoichiometric mixing ratios. PEC/protein conjugates were prepared by adding charged protein solutions to dispersions of respective like charged PEC particles, followed by one centrifugation step. Mixing proteins and PEC particles under attractive conditions led to flocculation of the dispersion. From CD, DLS and AFM the following trend for protein binding at PEC particles under repulsive conditions was obtained: HSA/PEC-1.50 > MYO/PEC-1.50 > LYZ/PEC-0.66. Protein uptakes up to 0.33 g x g(-1) (protein/PEC) (CD) and particle diameter enlargements up to 13 nm (AFM) were obtained at c(PROT) = 0.091 mg . mL(-1). Furthermore, novel spin coated films of PEC particles were interacted with proteins under both repulsive and attractive conditions. In-situ ATR FT-IR spectroscopy revealed that the adsorbed amount of HSA and LYZ under attractive conditions was significantly higher than under repulsive ones, which is analogous to protein adsorption at polyelectrolyte multilayers terminated either by polycation or polyanion. Similarly to the dispersed PEC/protein conjugates, under repulsive conditions the uptake of HSA was higher compared to LYZ. The shown protein uptake under repulsive conditions is related to concepts of mild enzyme or protein binding at nonbiogenic substrates.     

多变鱼腥藻藻胆蛋白共价复合物的合成及其分子内能量传递

利用双功能基偶联剂3-(2-吡啶联巯基)丙酸N-羟基琥珀酰亚胺酯(SPDP)合成了两个藻胆蛋白复合物,藻红蓝蛋白-变藻蓝蛋白复合物PEC-APC和藻红蓝蛋白-藻蓝蛋白复合物PEC-PC.利用吸收光谱和荧光光谱证明了藻胆蛋白构型与构象在反应后得到保持。通过荧光光谱观察到能量传递现象。计算出复合物PEC-APC的分子内能量传递效率约为90%.复合物PEC-PC中藻红蓝蛋白PEC的荧光寿命比PEC本身的寿命大大缩短,证明存在分子内能量传递。二硫苏糖醇(DTT)还原二硫桥键后能量传递被阻断。这进一步证明复合物合成成功及分子内能量传递。     

提高氧化铁光电催化分解水效率的策略进展

为了解决能源危机与环境污染问题,发展一种可再生的清洁能源至关重要.太阳能是一种取之不尽用之不竭的清洁能源,而氢气是一种良好的能源载体.利用太阳能光电催化水分解制氢,是一项有望能够解决能源与环境问题的技术,具有很大的应用前景.其中,氧化铁因为具有合适的能带位置与带隙、良好的稳定性与廉价无毒等优点,成为一种理想的光阳极材料.但是,在实际的测试中,氧化铁仅仅只能得到一个较低的光电转换效率,这可能是因为其较短的空穴扩散距离、较低的电导率以及极度缓慢的水氧化反应动力学所致.整个光电催化水氧化可分为三个过程,即光吸收过程、电荷分离过程以及表面空穴注入过程.这三个过程的效率共同决定了器件的太阳能转化效率.鉴于此,本文将从如何提高这三个效率的角度出发,总结近期研究报道中提高氧化铁光电催化分解水效率的一些策略.光吸收过程是指半导体中价带的电子在吸收具有一定能量的光子后发生跃迁,产生空穴-电子对的过程.其光子的损失主要来源于光的反射、透射以及半导体吸收边的限制.提高光吸收效率的主要策略包括制备具有特定纳米结构的氧化铁电极、利用表面等离子体共振效应以及组成双光吸收系统和掺杂等.电荷分离过程指的是受光激发产生的空穴电子对,在内建电场的作用下发生电荷分离,即光生空穴流向电极表面,光生电子流向半导体内部并从外电路导出.电荷分离效率的损失主要来源于光生载流子在迁移过程中的复合.因此,为了提高电荷分离效率,常见的策略是提高载流子在电荷分离过程中的复合时间τ₁和减少电荷迁移到表面(空穴)或者基底(电子)的时间τ₂.具体的策略包括制备特定的纳米结构(缩短体表相距离,减少τ₂)、构建异质结(增强能带弯曲,提高τ₁和减少τ₂)、掺杂(减少τ₂)和钝化复合中心(提高τ₁)等.表面空穴注入是指到达表面的光生空穴发生水氧化反应生成氧气的过程.除了空穴注入外,表面还可能存在复合与逆反应过程.因此,为了提高表面空穴注入效率,我们既可以提高水氧化反应动力学,具体的手段包括引入水氧化催化剂、F掺杂和碱处理等;也可以采用减少复合反应的策略,具体的方法包括引入钝化层、酸处理和高温热处理等;还可以采用减少逆反应的方法,最常见的手段就是在基底与氧化铁层之间引入电子阻挡层.上述三种途径都能提高表面空穴注入效率.最后,通过结合上述的一些策略,目前得到的最高性能的氧化铁电极在1.23 V(相对于可逆氢电极)能够达到6 mA cm^?2的光电催化分解水电流,但这个值依然明显低于氧化铁的理论值(12.6 mA cm^?2).这可能是由于体相复合所致.除此之外,氧化铁表面的水氧化机理现在依然不清晰,这些都是需要我们在未来解决的问题.     

Near infrared-driven photoelectrochemical water splitting: Review and future prospects

Photoelectrochemical (PEC) water splitting supplies an environmentally friendly, sustainable approach to generating renewable hydrogen fuels. Oxides semiconductors, e.g. TiO₂, BiVO₄, and Fe₂O₃, have been widely developed as photoelectrodes to demonstrate the utility in PEC systems. Even though significant effort has been made to increase the PEC efficiency, these materials are still far from practical applications. The main issue of metal oxides is the wide bandgap energy that hinders effective photons harvesting from sunlight. In solar spectrum, over 40% of the energy is located in the near-infrared (NIR) region. Developing sophisticated PEC systems that can be driven by NIR illumination is therefore essential. This review gives a concise overview on PEC systems based on the use of NIR-driven photoelectrodes. Promising candidates as efficient yet practical NIR-responsive photoelectrodes are suggested and discussed. Future outlooks on the advancement of PEC water splitting are also proposed.     

Needlelike and spherical polyelectrolyte complex nanoparticles of poly(l-lysine) and copolymers of maleic acid

We report on the bulk and surface properties of dispersions consisting of nonstoichiometric polyelectrolyte complex (PEC) nanoparticles. PEC nanoparticles were prepared by mixing poly(l-lysine) (PLL) or poly(diallyldimethylammonium chloride) (PDADMAC) with poly(maleic acid-co-alpha-methylstyrene) (PMA-MS) or poly(maleic acid-co-propylene) (PMA-P). The monomolar mixing ratio was n-/n+ = 0.6, and the concentration ranged from 1 to 6 mmol/L. Subsequent centrifugation enabled the separation of the excess polycation, resulting in a stable coacervate phase further used in the experiments. The bulk phase parameters turbidity and hydrodynamic radius (R(h)) of the PEC nanoparticles showed a linear dependence on the total polymer content independently of the mixed polyelectrolytes. This can be interpreted by the increased collision probability of the polyelectrolyte chains when the overlap concentration is approached or exceeded. Different morphologies of the cationic PEC nanoparticles, which were solution-cast onto Si supports, were obtained by atomic force microscopy (AFM). The combinations of PLL/PMA-MS and PDADMAC/PMA-MS revealed more or less hemispherical particle shapes, whereas that of PLL/PMA-P revealed an elongated needlelike particle shape. Circular dichroism and attenuated total reflection Fourier transform infrared (ATR-FTIR) measurements proved the alpha-helical conformation for the PEC PLL/PMA-P and the random coil conformation for the PEC PLL/PMA-MS. We conclude that stiff alpha-helical PLL induces anisotropic elongated PEC nanoparticles, whereas randomly coiled PLL forms isotropic spherical PEC nanoparticles.     

Current Advances in Quantum‐Dots‐Based Photoelectrochemical Immunoassays

As a newly developed technique, photoelectrochemical (PEC) immunoassays have attracted great attention in recent years because of their low cost and desirable sensitivity. Because the detection signal originates from the photoelectric conversion of photoelectric materials, the appearance and application of quantum dots (QDs), which possess unique photophysical properties and regulated optoelectronic characteristics, has taken the development of PEC immunoassays to new heights. This review concisely introduces the general mechanism of QDs‐based photoelectric conversion for immunoassays and summarizes the current advances in QD applications in immunoassays. Given that signal strategies and photoactive materials are the key elements in PEC biosensor systems, we comprehensively highlight the state‐of‐the‐art signaling strategies and various applications of QDs in PEC immunoassays to introduce advances in QDs‐based PEC immunoassays. Finally, challenges and future developmental trends are briefly discussed     

Signal-off Photoelectrochemical Aptasensor for S. aureus Detection Based on Graphite-like Carbon Nitride Decorated with Nickel Oxide

A signal-off photoelectrochemical (PEC) aptasensor was proposed for pathogenic bacteria detection based on graphite-like carbon nitride decorated with NiO. The S. aureus be captured by the specific recognition of DNA aptamer, which was immobilized on the PEC electrode surface according to the specific effect of carboxylic group and NiO. The PEC signal would be obviously suppressed due to the transfer blocking of electron donor to PEC active material surface by steric hindrance and electrostatic repulsion. The PEC aptasensor showed excellent specificity and high sensitivity for S. aureus, and this provides simple strategy to construct point-of-care testing aptasensor for bacteria analysis.