دانلود رایگان مقاله انگلیسی فراتر از برچسب ها: بررسی استفاده از نقاط کوانتومی به عنوان اجزای تلفیقی سنجش ها، بیوپروب ها و بیوسنسور ها با استفاده از ترارسانی نوری به همراه ترجمه فارسی
| عنوان فارسی مقاله: | فراتر از برچسب ها: بررسی استفاده از نقاط کوانتومی به عنوان اجزای تلفیقی سنجش ها، بیوپروب ها و بیوسنسور ها با استفاده از ترارسانی نوری |
| عنوان انگلیسی مقاله: | Beyond labels: A review of the application of quantum dots as integrated components of assays, bioprobes, and biosensors utilizing optical transduction |
| رشته های مرتبط: | فیزیک، مهندسی اپتیک و لیزر، بیوفتونیک، فیزیک کاربردی و نانو فیزیک |
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| نشریه | الزویر – Elsevier |
| کد محصول | f432 |
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بخشی از ترجمه فارسی مقاله: 1. مقدمه
2. نقاط کوانتومی: شیمی سطح و کانجوگه ها |
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بخشی از مقاله انگلیسی: 1. Introduction Quantum dots (QDs) are one of several types of nanomaterial that have had a significant impact on research in many fields across the physical, chemical, and biological sciences. QDs are semiconductor nanocrystals that generally have dimensions in the range of 2–6 nm. Multidisciplinary interest in QDs has been largely motivated by their unique electro-optical properties that lie between the molecular and bulk semiconductor regimes [1]. Although QD research gained momentum in the early 1990s, it was arguably the adoption of QD-bioconjugates as fluorescent labels for biological imaging [2,3] that catalyzed significant interest across the bioanalytical, biophysical, and biomedical research communities at the turn of the century. QDs are recognized as frequently providing better brightness and photostability compared to conventional fluorescent dyes, while also being better suited for multicolour applications [4]. At present, QDs continue to make an impact in these fields through cellular, tissue, or whole body imaging [4–8], and the development of optical probes for biological sensing [4,5,9–12]. This review addresses the development of bioassays, bioprobes, and biosensors utilizing QDs as an integrated component of the analysis. We make a distinction between “non-integrated” and “integrated” QDs based on design. A non-integrated QD is one that is selectively introduced to a bioanalysis as a consequence of biorecognition. Examples include the use of QDs as fluorescent labels in microarrays [13,14], or electroactive labels in assays based on anodic stripping voltammetry [15]. In contrast, an integrated QD is one that is present in a system throughout a bioanalysis—it simultaneously has a role in transduction and as a scaffold for biorecognition. In many cases, this requires the direct conjugation of affinity probes or biorecognition elements to a QD, or their co-assembly at an interface. The key point is that transduction occurs by modulating QD luminescence between high/low or on/off states. The bioassays, bioprobes, and biosensors discussed herein are primarily limited to those with integrated QDs and optical transduction. The modulation of QD luminescence as a selective response to the presence of target analyte can be achieved in several ways. These include, but are not necessarily limited to: fluorescence resonance energy transfer (FRET), bioluminescence resonance energy transfer (BRET), charge transfer (CT) quenching, and electrochemiluminescence (ECL). The photoluminescence (PL) of QDs is strongly influenced by CT reactions, while QDs have been demonstrated to be excellent donors in FRET and acceptors in BRET. The strong distance dependence of these processes has provided the basis for many detection strategies. Biorecognition events are used to modulate distances between proximal redox active species, chromophores, or fluorophores. Concomitant changes in PL spectra and intensity provide an analytical signal. The modulation of ECL intensity from QDs using analyte reactivity, enzyme turnover, or changes in co-reactant mass transport has also been used to provide an analytical signal. The basic principles underlying these detection strategies are presented in this review, along with an overview of their applications in the selective detection of small molecules, ions, nucleic acids, proteins, enzymes, and other biologically important targets. Some special attention is given to recent developments in solid-phase assays, which can provide unique advantages compared to their more widely employed solution-phase counterparts. The review of analytical applications is prefaced by a brief overview of QDs, with emphasis on their interfacial chemistry and bioconjugation. 2. Quantum dots: surface chemistry and conjugates 2.1. Quantum dots The unique electro-optical properties of QDs arise from the combination of material and dimensionality, the latter known as “quantum confinement” [4,5,16,17]. Despite the emergence of other materials [18–25], the most popular material choices remain CdSe and CdTe [1,26–34]. The synthetic methods and characterization for high-quality QDs composed of these materials are widely available, and PL in the visible and near-IR regions of the spectrum is obtained. Typically, core–shell structures with an inorganic capping layer of ZnS around the core nanocrystal are used to improve luminescence properties (e.g. CdSe/ZnS) [26,29,30,34]. The favorable optical properties of QDs include: strong, broad, one-photon and two-photon absorption; narrow, symmetric, size-tunable PL (full-width-at-half maximum, FWHM, ca. 25–35 nm); potentially high quantum yield (>20%); and generally long PL decay times (often > 10 ns) [4,5,17,35]. Other, often less desirable, optical features of QDs can include: multi-exponential PL decay, bluing, brightening, and blinking at the single QD level [36]. Due to the large surface area-to-volume ratios of QDs, the quality and characteristics of the nanocrystal surface are tantamount to the quality of the core in determining the observed PL properties. Decreases in quantum yield, changes in PL decay, spectral shifts, and the appearance of undesirable band-gap PL can be associated with surface states. The growth of a high-quality inorganic shell around the core nanocrystal reduces the impact of surface states on PL. However, the influence of the QD surface cannot be eliminated; adsorbates, ligands, or other coatings can affect PL properties. This is not necessarily a detriment—the ability of core carriers (i.e. electrons and holes) to interact with states in the surrounding matrix are essential in many applications involving CT. Surface chemistry is a critically important consideration in developing all types of assays, bioprobes, and biosensors based on QDs. In addition to retaining the favourable optical properties of QDs, the surface chemistry of choice should also allow bioconjugation, impart aqueous solubility, and not impede the efficient use of FRET, BRET, CT, or ECL as a transduction method. With respect to efficient transduction, the thickness of the coating is a very important consideration. Many of the studies described in this review have used compact ligand-based QD coatings to minimize thickness, although polymer and polymer–protein coated QDs have also been successfully used in FRET and BRET methods. |