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Die Kompartimentierung von Reaktionen in Femtoliter(fL)-Gefasen und die Integration von fL-Gefasen in Arrays verstarkt und beschleunigt nicht nur die chemische und biochemische Analyse, sondern fuhrt auch zu neuen wissenschaftlichen Methoden und Erkenntnissen. Dieser Aufsatz stellt die verschiedenen fL-Gefase und Array-Formate vor und lotet ihre Anwendungen fur den Nachweis und die Charakterisierung von biologisch bedeutsamen Analyten aus. Wenn fL- Arrays mit Analyten, Sonden oder Zellen bestuckt werden, konnen tausende analytischer Messungen parallel durchgefuhrt werden. Der Einschluss einzelner Enzymmolekule in fL-Arrays ermoglicht die gleichzeitig Analyse einer Vielzahl individueller Enzymmolekule. Neue Nanofabrikationstechniken und immer empfindlichere Nachweismethoden sind die treibende Kraft auf dem Gebiet der analytischen Chemie “im Femtoliter”. Unsere Ubersicht befasst sich insbesondere mit dem Fortschritt und den Herausforderungen auf dem Gebiet der analytischen Chemie im fL mit Beispielen sowohl aus der Grundlagenforschung als auch aus der angewandten Forschung.

Optical-fiber bundles have been employed as a versatile substrate for the fabrication of high-density microwell arrays. In this minireview, we discuss the application of optical-fiber-bundle arrays for a variety of biological problems. For genomics studies and microbial pathogen detection, individual beads have been functionalized with DNA probes and then loaded into the microwells. In addition, beads differentially responsive to vapors have been employed in an artificial olfaction system. Microwell arrays have also been loaded with living cells to monitor their individual response to biologically active compounds over long periods. Finally, the microwells have been sealed to enclose single enzyme molecules that can be used to measure individual molecule catalytic activity.

Photon-upconverting nanoparticles (UCNPs) are lanthanide-doped nanocrystals that emit visible light under near-infrared excitation (anti-Stokes emission). This unique optical property precludes background fluorescence and light scattering from biological materials. The emission of multiple and narrow emission lines is an additional hallmark of UCNPs that opens up new avenues for optical encoding. Distinct emission signatures can be obtained if the multiple emission of UCNPs is tuned by their dopant composition or by surface modification with dyes. Tuning the intensity of only one of the multiple emission lines and using another one as a constant reference signal enables the design of ratiometric codes that are resistant to fluctuations in absolute signal intensities. Combining several UCNPs each displaying a distinct set of emission lines expands the coding capacity exponentially and lays the foundation for highly multiplexed analyte detection. This Review highlights the potential of UCNPs for labeling and encoding biomolecules, microspheres, and even whole cells.

The compartmentalization of reactions in femtoliter (fL) containers and integration of fL containers into arrays not only enhances and accelerates chemical and biochemical analysis but also leads to new scientific methods and insights. This review introduces various fL container and array formats and explores their applications for the detection and characterization of biologically relevant analytes. By loading analytes, sensing elements, or cells into fL arrays, one can perform thousands of analytical measurements in parallel. Confining single enzyme molecules in fL arrays enables one to analyze large numbers of individual enzyme molecules simultaneously in solution. New nanofabrication techniques and progressively more sensitive detection methods drive the field of fL analytical chemistry. This review focuses on the progress and challenges in the field of fL analytical chemistry with examples of both basic and applied research.