Direct writing of optical microresonators in a lab-on-a-chip for label-free biosensing.

Whispering gallery mode (WGM) resonators are promising optical structures for microfluidic label-free biosensors mainly due to their high sensitivity, but from a practical point of view they present numerous constraints that make their use in real laboratory diagnosis application difficult. Herein we report on a monolithic lab on a chip fabricated by a hybrid femtosecond laser micromachining approach, for label-free biosensing. It consists of a polymer WGM microresonator sensor integrated inside a glass microfluidic chip, presenting a refractive index change sensitivity of 61 nm per RIU. The biosensing capabilities of the device have been demonstrated by exploiting the biotin-streptavidin binding affinity, obtaining a measurable minimum surface density increase of 67 × 103 molecules per µm2.

An optofluidic constriction chip for monitoring metastatic potential and drug response of cancer cells.

Cellular mechanical properties constitute good markers to characterize tumor cells, to study cell population heterogeneity and to highlight the effect of drug treatments. In this work, we describe the fabrication and validation of an integrated optofluidic chip capable of analyzing cellular deformability on the basis of the pressure gradient needed to push a cell through a narrow constriction. We demonstrate the ability of the chip to discriminate between tumorigenic and metastatic breast cancer cells (MCF7 and MDA-MB231) and between human melanoma cells with different metastatic potential (A375P and A375MC2). Moreover, we show that this chip allows highlighting the effect of drugs interfering with microtubule organization (paclitaxel, combretastatin A-4 and nocodazole) on cancer cells, which leads to changes in the pressure-gradient required to push cells through the constriction. Our single-cell microfluidic device for mechanical evaluation is compact and easy to use, allowing for an extensive use in different laboratory environments.

An integrated optofluidic device for single-cell sorting driven by mechanical properties.

We present a novel optofluidic device for real-time sorting on the basis of cell mechanical properties, measured by optical stretching. The whole mechanism, based on optical forces, does not hamper the viability of the tested cells, which can be used for further analysis. The device effectiveness is demonstrated by extracting a sample population enriched with highly metastatic cells from a heterogeneous cell mixture.

Optofluidic integrated cell sorter fabricated by femtosecond lasers.

The main trend in optofluidics is currently towards full integration of the devices, thus improving automation, compactness and portability. In this respect femtosecond laser microfabrication is a very powerful technology given its capability of producing both optical waveguides and microfluidic channels. The current challenge in biology is the possibility to perform bioassays at the single cell level to unravel the hidden complexity in nominally homogeneous populations. Here we report on a new device implementing a fully integrated fluorescence-activated cell sorter. This non-invasive device is specifically designed to operate with a limited amount of cells but with a very high selectivity in the sorting process. Characterization of the device with beads and validation with human cells are presented.

Los movimientos elementales complejos del humano: Desarrollo postnatal. Reporte preliminar de nueve lactantes mexicanos / The complex elementary human movements: Normal postnatal development. Preliminar report of nine Mexican infants

Introduction The study of the early neonatal and infant behavior has called the attention of several researchers with the purpose of establishing an early diagnostic of neurological damage. Ferenc Katona identifies, from the 28th week of gestation to the third month of extrauterine life, a group of locomotion and verticalization innate behaviors which are called Complex Elementary Movements (CEM). These sequences of generalized motor activity of central origin, with automatic movements, generate sensory impulses to the spinal cord, brainstem and superior systems in response to gravitational and acceleration stimulus. These impulses cause continuous and repetitive movements of the head, trunk and limbs, and lead to verticalization and locomotion. They also prefigure the human behavior by organizing structures and cerebral functions ontogenetically mature at birth and with greater resistance to damage. In normal European neonates and infants, the constancy and stability has allowed for the diagnose of early Nervous System dysfunction (SN). European researchers have applied procedures that include CEM for neurohabilitation. Katona explains that when CEM are induced, they stimulate the vestibular system performance. The repetitive and/or sustained muscular contractions of trunk and extremities during the attempts of verticalize or locomotion, transmit new stimulus that strengthen the initial stimulation. During the time that the infant maintains the pattern activation, the thalamus, basal ganglia and cerebral cortex are stimulated, simultaneously and proportionally, occurring changes in the muscular tone, the movement dynamics and posture within a critical period of cerebral plasticity. The movements of head, trunk and extremities are refined or reorganized as in normal child maturity (development). This prevents and avoids risks and altered functions. In Mexico, according to the information sources reviewed, there are no studies describing the normal postnatal development variations. It is important to differentiate normal movements from the pathological ones to make early diagnosis of neurological damage in Mexican populations. Material and methods The Tlalpan outpatient family medicine clinic of the Institute of Security and Social Services for State Employees (ISSSTE) referred 25 infants, considered with low perinatal biological risk, residents of Mexico City. The Heinz Prechtl neurological sieve was applied to each infant to confirm an adequate neurological maturity. Fifteen infants fulfilled the inclusion criteria, the parents of nine infants agreed on their child participation in four evaluations, scheduled monthly, according to the day of birth. The parents signed the informed consent letter. In each evaluation, the ten maneuvers of activation were applied twice. They were distributed 6 at the first month, 9 at 2 and 3 months, and 8 at 4 months. Five maneuvers were applied to activate locomotion: Mcgraw, Bauer, reinforced Bauer, crawling on an inclinate slide and assisted crawling. Also five maneuvers were put into practice for verticalization: carry sitting, antigravity verticalization, stand up reaction, elementary walking and sitting in the air. Five behaviors and movements were described: crying, visual behavior (eyes closed or open with or without visual fixation), limbs, trunk and head movements. The evaluations were recorded in 8mm digital format and reviewed instantly during the evaluation. The camera's timer was used to measure the time they took to activate movements of locomotion or verticalization. To calculate frequencies and central tendency measures, the SAS statistical software JMP, version 7.0 was used. Results 320 activating maneuvers were used, 82.5% activated locomotion and 58% verticalization. The children awoked spontaneously with rude movements and cried, in 63% of the evaluations including the five locomotion patterns: 58.7% in the Alternating Cross Pattern (ACP), 10% for the Incomplete Simultaneous Pattern (ISP), 10% in the Lower Limb Alternating Pattern (LLAP), 1.25% on Complete Simultaneous Pattern (CSP) 2.5% and Homolateral Pattern (HP). The most frequent pattern observed was the Alternate Cross Pattern (PAC) 58.7% and the less frequent was the Homolateral Pattern (PH) 1.25%. In verticalization two patterns were observed: 58% with complete trunk and head alignment, 42% with incomplete alignment. The latencies to enable MEC were from 0-120 seconds, with M 27.7, DE ±48.8 for locomotion and M 9.43, DE ±20.7 for verticalization. Opening the eyes and visual fixation in the locomotion maneuvers occurred in the 43%, 20% in the first month, 31% in the 2nd month, 42% in the 3rd month and 75% in the 4th month. Verticalization maneuvers occurred in 64%, 47% in the first month, 49% in the second month, 64% in the 3rd month and 95% in the 4th month. As the children grew, the open eye and visual fixation conducts increased in presence. Locomotion appeared in the 43% of the children and verticalization in 64%. Discussion Katona reports that the MEC activation is given from birth to three months, with exception in two maneuvers: crawling on an inclined slide that appears until two months and on the four month the manifestation of elementary march. In this research, the locomotion and ver-ticalization patterns appeared sometimes until the fourth month, with frequencies that change in 12% to 100% of the cases according to the maneuvers form. Two patterns were identified but not described, the PH with a case frecuency of 1.25% and the PSC with 2.5%. Katona suggested that infants up to three months old are able to activate several seconds to complete verticalization, due to vestibular activity. In our experience, until two months they are mainly short and incomplete patterns of vertical integration then completed and sustained during the third and fourth month. Concerning the time required to activate MEC, Katona reported latencies of 5-100 sec. with absence of responses until the 4th month. Except for elementary walking, we observed that the latency time varies with age. In this investigation the locomotion time was 27.7 sec average, founding 0-120 sec intervals. In verticalization, latencies were faster than the average latency time of 9.43 sec. With intervals of latency in the first two months of age of 0-19 sec. elementary walking and the stand up reaction with age took but in activating and to the fourth month in several cases no longer they appeared. Katona reported that the newborn is capable of a brief visual fixation with the presentation of the face or with a flashing object 20cm away. The results of the locomotion and verticalization maneuvers showed that the behavior was present in the first month, in less of the 50% locomotion assessments and in less of 70% in verticalization. When the maneuver allowed controlling the head or maintaining the face to face line sight, the infant opened and fixed visually. Conclusions In the nine Mexican infants explored, variations were reported in the postnatal MEC evolution, with respect to the age of appearing, patterns type, trunk and limbs movements, time required for activation (latencies), visual activity and crying presence were not observed. If these variations are confirmed we could establish more accurate reference parameters and analyze their relationship with biological and environmental factors. Thus, to strengthen a prevention method in neurohabilitation/neurorehabilitation for high-risk population benefit.

Introducción Con el propósito de diagnosticar tempranamente el daño neurológico, Ferenc Katona identifica desde la semana 28 de gestación hasta los tres meses de vida extrauterina un grupo de comportamientos innatos de locomoción y verticalización, a los cuales se les denomina Movimientos Elementales Complejos (MEC). Son secuencias de actividad motora generalizada automática de origen central provocadas por estímulos gravitacionales y de aceleración. Su activación genera impulsos sensoriales al cordón espinal, al tallo cerebral y a los sistemas superiores, lo que resulta en movimientos continuos y repetidos de la cabeza, del tronco y de las extremidades dirigidos a la verticalización y a la locomoción. La constancia y estabilidad en la normalidad de los MEC en neonatos y lactantes europeos ha permitido diagnosticar la disfunción temprana del Sistema Nervioso (SN) y utilizarlos como procedimientos de neurohabilitación. En México, con base en las fuentes de información revisadas, no hay estudios que describan las variaciones del desarrollo normal postnatal por lo que es importante conocerlas y tener un referente para diferenciar las normales de las patológicas. Material y métodos La consulta externa de la Clínica de Medicina Familiar Tlalpan, del Instituto de Seguridad y Servicios Sociales de los Trabajadores del Estado (ISSSTE), refirió 25 lactantes considerados de bajo riesgo perinatal, a quienes se les aplicó el Tamiz neurológico de Heinz Prechtl para confirmar una adecuada madurez neurológica. Quince de los lactantes cumplieron con los criterios de inclusión. Los padres de nueve lactantes aceptaron llevar a sus hijos a las cuatro evaluaciones programadas mensualmente de acuerdo al día en que nacieron y firmaron la carta de consentimiento informado. En cada evaluación se aplicaron dos veces las diez maniobras de activación (cuadro 1). Las variables de estudio son: presencia de llanto, comportamiento visual, movimientos de extremidades, tronco y cabeza. Las valoraciones se filmaron en formato digital de 8mm. El cronómetro de la cámara midió el tiempo que tomaba cada maniobra en activar los movimientos (latencia). Se utilizó el programa estadístico JMP de SAS, versión 7.0, para el cálculo de frecuencias y medidas de tendencia central. Resultados Se provocaron 320 maniobras, de las cuales se activaron 82.5% en locomoción y 58% en verticalización. El 63% de los niños estuvieron despiertos con movimientos groseros y llanto. De los patrones de locomoción, el de mayor frecuencia fue el Patrón Alterno Cruzado (PAC), con 58.7%, y el de menor frecuencia fue el Patrón Homolateral (PH), con 1.25%. En la verticalización, su presencia fue de 58%, con alineación completa del tronco y la cabeza, y 42% con alineación incompleta. Se obtuvieron latencias de activación, para la locomoción, entre 0-120 segundos, con una media de 27.7±48.8 y para la verticalización una media de 9.43±20.7. El comportamiento visual, abrir ojos y fijación visual aumentó conforme el niño crecía. Discusión Katona reporta que la activación de los MEC se presenta al nacimiento y hasta los tres meses, con excepción de dos maniobras: gateo en plano inclinado, presente hasta los dos meses, y marcha elemental que se observa hasta el cuarto mes. En esta investigación, los patrones para locomoción y verticalización pudieron provocarse hasta el cuarto mes con frecuencias que variaron de un 12% a un 100%, de acuerdo al tipo de maniobra. Se identificaron dos patrones no descritos: el PH, con 1.25%, y el Patrón Simultáneo Completo (PSC), con 2.5%. La verticalización completa apareció y aumentó en frecuencia con la edad en nuestra población. En cuanto a la locomoción se obtuvieron variaciones en el movimiento de las extremidades, el tronco y el tiempo de latencia. Cuando la maniobra permitió controlar la cabeza o mantener la línea de la mirada frente a frente, el lactante abrió los ojos y fijó visualmente. Conclusiones Se documento la variabilidad de los MEC en niños mexicanos de bajo riesgo, mostrando que éstos evolucionan desde patrones de menor verticalización, con llanto frecuente y escasa fijación visual al nacimiento a patrones de verticalización completa, mayor fijación y disminución del llanto, lo cual comprende una modificación al criterio de calificación propuesto por los autores para niños europeos. Los ajustes al procedimiento tienen implicación en la detección temprana de riesgos para la discapacidad motriz.

Fabrication of photonic devices in nanostructured glasses by femtosecond laser pulses.

Focused femtosecond laser pulses have been used to modify the optical properties of glass doped with CdSxSe1-x nanocrystals. Large positive refractive index changes have been observed and exploited for the fabrication of photonic devices. In particular, we report on highly confining optical waveguides and single and multi-layer volume diffraction gratings.