Hollow-Core Fiber-Based Biosensor: A Platform for Lab-in-Fiber Optical Biosensors for DNA Detection

In this paper, a novel platform for lab-in-fiber-based biosensors is studied. Hollow-core tube lattice fibers (HC-TLFs) are proposed as a label-free biosensor for the detection of DNA molecules. The particular light-guiding mechanism makes them a highly sensitive tool. Their transmission spectrum is featured by alternations of high and low transmittance at wavelength regions whose values depend on the thickness of the microstructured web composing the cladding around the hollow core. In order to achieve DNA detection by using these fibers, an internal chemical functionalization process of the fiber has been performed in five steps in order to link specific peptide nucleic acid (PNA) probes, then the functionalized fiber was used for a three-step assay. When a solution containing a particular DNA sequence is made to flow through the HC of the TLF in an 'optofluidic' format, a bio-layer is formed on the cladding surfaces causing a red-shift of the fiber transmission spectrum. By comparing the fiber transmission spectra before and after the flowing it is possible to identify the eventual formation of the layer and, therefore, the presence or not of a particular DNA sequence in the solution

Hollow Core Inhibited Coupling Fibers for Biological Optical Sensing

In this work, we report how tube lattice hollow-core fibers can be successfully used to build sensors for molecule detection. The inner silica surface of the fiber is functionalized and coated with a probe layer, which permits to bond only with a particular molecule (the target). When the fiber is infiltrated with a solution containing the target an additional layer is crated on the silica surface causing a redshift of the fiber transmission spectrum. The technique does not require any additional transducer component such as Bragg gratings, amplifying techniques such as nano-particles nor coherent sources. It simply consists of the measurement of the transmission spectrum of a piece of fiber some tens centimeters long. The principle is validated with experimental results showing the detection of streptavidin protein. A solution containing streptavidin was flowed trough the hollow core of the fiber coated with biotine. The measurement of the transmitted spectrum before and after the infiltration showed the presence of a some nanometer thick bio-layer

Emotion Recognition in Parkinson's disease after Subthalamic Deep Brain Stimulation: Differential effects of lesion and STN stimulation

Deep brain stimulation of the subthalamic nucleus (STN-DBS) has acquired a relevant role in the treatment of Parkinson\u2019s disease (PD). Despite being a safe procedure, it may expose patients to an increased risk to experience cognitive and emotional difficulties. Impair- ments in emotion recognition, mediated both by facial and prosodic expressions, have been reported in PD patients treated with such procedure. However, it is still unclear whether the STN per se is responsible for such changes or whether others factors like the microlesion produced by the electrode implantation may also play a role. In this study we evaluated facial emotions discrimination and emotions recognition using both facial and prosodic expressions in 12 patients with PD and 13 matched controls. Patients\u2019 were tested in four conditions: before surgery, both in on and off medication, and after surgery, respectively few days after STN implantation before turning stimulator on and few months after with stimulation on. We observed that PD patients were impaired in discriminating and recognizing facial emotions, especially disgust, even before DBS implant. Microlesion caused by surgical procedure was found to influence patients\u2019 performance on the discrimination task and recognition of sad facial expression while, after a few months of STN stimulation, impaired disgust recognition was again prominent. No impairment in emotional prosody recognition was observed both before and after surgery. Our study confirms that PD patients may experience a deficit in disgust recognition and provides insight into the differential effect of microlesion and stimulation of STN on several tasks assessing emotion recognition