Multi-wavelength fluorescence sensing with integrated waveguides in an optofluidic chip

Femtosecond-laser-written integrated waveguides enable multi-wavelength fluorescence sensing of flowing biomolecules in an optofluidic chip. Fluorescence from differently labeled biomolecules with distinct absorption wavelengths, encoded by uniquely modulating each excitation beam, is detected by a color-blind photodetector, and the origin of each signal is unraveled by Fourier analysis

Multi-color fluorescent DNA analysis in an integrated optofluidic lab-on-a-chip

Sorting and sizing of DNA molecules within the human genome project has enabled the genetic mapping of various illnesses. By employing tiny lab-on-a-chip devices for such DNA analysis, integrated DNA sequencing and genetic diagnostics have become feasible. However, such diagnostic chips typically lack integrated sensing capability. We address this issue by combining microfluidic capillary electrophoresis with laser-induced fluorescence detection resulting in optofluidic integration towards an on-chip bio-analysis tool [1,2]. We achieve a spatial separation resolution of 12 μm, which can enable a 20-fold enhancement in electropherogram peak resolution, leading to plate numbers exceeding one million. We demonstrate a high sizing/calibration accuracy of 99% [3], and ultrasensitive fluorescence detection (limit of detection = 65 femtomolar, corresponding to merely 2-3 molecules in the excitation/detection volume) of diagnostically relevant double-stranded DNA molecules by integrated-waveguide laser excitation. Subsequently, we introduce a principle of parallel optical processing to this optofluidic lab-on-a-chip. Different sets of exclusively color-labeled DNA fragments – otherwise rendered indistinguishable by their spatio-temporal coincidence – are traced back to their origin by modulation-frequency-encoded multi-wavelength laser excitation, fluorescence detection with a color-blind photomultiplier, and Fourier-analysis decoding. As a proof of principle, fragments from independent human genomic segments, associated with genetic predispositions to breast cancer and anemia, are extracted by multiplex ligation-dependent probe amplification, and simultaneously analyzed. Such multiple yet unambiguous optical identification of biomolecules opens new horizons for “enlightened” lab-on-a-chip devices

Multi-point, multi-wavelength fluorescence monitoring of DNA separation in a lab-on-a-chip with monolithically integrated femtosecond-laser-written waveguides

Electrophoretic separation of fluorescently labeled DNA molecules in on-chip microfluidic channels was monitored by integrated waveguide arrays, with simultaneous spatial and wavelength resolution. This is an important step toward point-of-care diagnostics with multiplexed DNA assays

Neuraminidase 1 Is a Negative Regulator of Lysosomal Exocytosis

SummaryLysosomal exocytosis is a Ca2+-regulated mechanism that involves proteins responsible for cytoskeletal attachment and fusion of lysosomes with the plasma membrane. However, whether luminal lysosomal enzymes contribute to this process remains unknown. Here we show that neuraminidase NEU1 negatively regulates lysosomal exocytosis in hematopoietic cells by processing the sialic acids on the lysosomal membrane protein LAMP-1. In macrophages from NEU1-deficient mice, a model of the disease sialidosis, and in patients' fibroblasts, oversialylated LAMP-1 enhances lysosomal exocytosis. Silencing of LAMP-1 reverts this phenotype by interfering with the docking of lysosomes at the plasma membrane. In neu1−/− mice the excessive exocytosis of serine proteases in the bone niche leads to inactivation of extracellular serpins, premature degradation of VCAM-1, and loss of bone marrow retention. Our findings uncover an unexpected mechanism influencing lysosomal exocytosis and argue that exacerbations of this process form the basis for certain genetic diseases

Observation of open scattering channels

The existence of fully transmissive eigenchannels ("open channels") in a random scattering medium is a counterintuitive and unresolved prediction of random matrix theory. The smoking gun of such open channels, namely a bimodal distribution of the transmission efficiencies of the scattering channels, has so far eluded experimental observation. We observe an experimental distribution of transmission efficiencies that obeys the predicted bimodal Dorokhov-Mello-Pereyra-Kumar distribution. Thereby we show the existence of open channels in a linear optical scattering system. The characterization of the scattering system is carried out by a quantum-optical readout method. We find that missing a single channel in the measurement already prevents detection of the open channels, illustrating why their observation has proven so elusive until now. Our work confirms a long-standing prediction of random matrix theory underlying wave transport through disordered systems.Comment: 9 pages including methods and supplementary materials. 3 figure

Integrated fluorescence sensing in a lab-on-a-chip for DNA analysis

We report on monolithic optical sensor integration in a lab-on-a-chip toward onchip diagnosis of all kinds of genetic diseases, e.g. breast cancer. Such an analysis of genetic diseases is based on the capillary electrophoresis separation of DNA fragments amplified from diagnostically relevant regions of the concerned gene.\ud This paper presents a proof of principle, demonstrating real time integrated fluorescence monitoring during the capillary electrophoresis separation of fluorescent dyes as well as fluorescently labeled DNA molecules in an on-chip microfluidic channel. To this end, sensing waveguides were integrated monolithically by means of femtosecond laser irradiation, in a commercial fused silica lab-on-a-chip, to perpendicularly intersect the microfluidic separation channel. Laser excitation through these waveguides induces fluorescence in the flowing microfluidic plugs. Depending on the number of species present, and the difference between their mobility, a corresponding number of electropherogram peaks are detected. \ud Detection has been performed by a CCD camera in order to visualize the on-chip events and to provide access to spatial information, as well as by a photomultiplier tube in order to detect low values of fluorescence signal. The present limit of detection is estimated to be approximately 6 nM. The presented setup achieves high spatial resolution due to the small cross section of the waveguides, ~12 μm. This is an improvement over the conventional approach to place a pinhole in the path of the fluorescence output signal generated by a broadband background illumination, e.g. with an Hg or a Xe lamp. Future work will focus on extension of this principle to real world diagnostic samples for development of a fast and compact point of care optical biosensing device.\ud During the conference we will present the latest results in wavelengthmultiplexed fluorescence monitoring of DNA separation at low limits of detection

Quantum photo-thermodynamics on a programmable photonic quantum processor

One of the core questions of quantum physics is how to reconcile the unitary evolution of quantum states, which is information-preserving and time-reversible, with the second law of thermodynamics, which is neither. The resolution to this paradox is to recognize that global unitary evolution of a multi-partite quantum state causes the state of local subsystems to evolve towards maximum-entropy states. In this work, we experimentally demonstrate this effect in linear quantum optics by simultaneously showing the convergence of local quantum states to a generalized Gibbs ensemble constituting a maximum-entropy state under precisely controlled conditions, while using a new, efficient certification method to demonstrate that the state retains global purity. Our quantum states are manipulated by a programmable integrated photonic quantum processor, which simulates arbitrary non-interacting Hamiltonians, demonstrating the universality of this phenomenon. Our results show the potential of photonic devices for quantum simulations involving non-Gaussian states

Detection of heavy metal ions by ISFETs in a flow injection analysis cell

An ion-selective field-effect transistor (ISFET) is chemically modified with a photopolymerizable and cyanopropyl modified polysiloxane containing N,N,N',N'-tetrabutyl-3,6-dioxaoctane-dithioamide as Cd2+ ionophore. This CHEMFET has a Nerstian response (30 mV/decade) to a change of cadmium activity in aqueous solutions. Selectivity coefficients of the CHEMFET towards potassium, calcium, copper, and lead are given. Preliminary results of the CHEMFET in a flow injection analysis cell without wire bonding and polymeric encapsulation are presented