RESUMO
This research presents a microfermentor integrated into an optical fiber sensor based on quasi-elastic light scattering (QELS) to monitor and swiftly identify cellular growth kinetic parameters. The system uses a 1310 nm laser light that is guided through single-mode silica optical fibers to the interior of perfusion chambers, which are separated by polycarbonate membranes (470 nm pores) from microchannels, where a culture medium flows in a constant concentration. The system contains four layers, a superior and an inferior layer made of glass, and two intermediate poly(dimethylsiloxane) layers that contain the microchannels and the perfusion chambers, forming a reversible microfluidic device that requires only the sealing of the fibers to the inferior glass cover. The QELS autocorrelation decay rates of the optical signals were correlated to the cells counting in a microscope, and the application of this microsystem to the monitoring of alcoholic fermentation of Saccharomyces cerevisiae resulted in the kinetic parameters of KM = 4.1 g/L and µm = 0.49 h-1. These results agree with both the data reported in the literature and with the control batch test, showing that it is a reliable and efficient biological monitoring system.
Assuntos
Tecnologia de Fibra Óptica/métodos , Dimetilpolisiloxanos/química , Difusão Dinâmica da Luz/métodos , Fermentação/fisiologia , Membranas , Cimento de Policarboxilato/química , Saccharomyces cerevisiae/metabolismoRESUMO
The Apico Aortic Blood Pump (AABP) is a centrifugal continuous flow left ventricular assist device (LVAD) with ceramic bearings. The device is in the initial development phase and is being designed to be attached directly to the left ventricular apex by introducing an inlet cannula. This paper reports results from in vitro experiments. In order to evaluate implantation procedures and device dimensioning, in vitro experiments included an anatomic positioning study for the analysis of surgical implantation procedure and device dimensions and positioning that was performed using the body of a pig. The results revealed no damage caused by the device, and the surgical implantation procedure was considered feasible. Hydrodynamic performance curves were obtained to verify the applicability of the device as an LVAD, showing adequate performance. Mechanical blood trauma was analyzed through 6-h hemolysis tests, with total pressure head of 100 mm Hg and flow of 5 L/min. Mean normalized index of hemolysis was 0.009 g/100 L (±0.002 g/100 L). Studies using a hybrid cardiovascular simulator were conducted for three types of circulatory conditions: normal healthy conditions, concentric hypertrophic heart failure (CHHF), and CHHF with AABP assistance. Analysis of cardiovascular parameters under those three conditions demonstrated that when the AABP was assisting the system, parameters under CHHF conditions went back to normal healthy values, indicating the AABP's effectiveness as CHHF therapy. Our preliminary results indicate that it is feasible to use the AABP as a LVAD. The next steps include long-term in vivo experiments.
Assuntos
Ventrículos do Coração/cirurgia , Coração Auxiliar , Animais , Cerâmica/química , Coração Auxiliar/efeitos adversos , Hemólise , Humanos , Hidrodinâmica , Modelos Cardiovasculares , Desenho de Prótese , SuínosRESUMO
Abstract: The Apico Aortic Blood Pump (AABP) is acentrifugal continuous flow left ventricular assist device(LVAD) with ceramic bearings. The device is in the initialdevelopment phase and is being designed to be attacheddirectly to the left ventricular apex by introducing an inletcannula. This paper reports results from in vitro experiments.In order to evaluate implantation procedures anddevice dimensioning, in vitro experiments included an anatomicpositioning study for the analysis of surgical implantationprocedure and device dimensions and positioningthat was performed using the body of a pig. The resultsrevealed no damage caused by the device, and the surgicalimplantation procedure was considered feasible. Hydrodynamicperformance curves were obtained to verify theapplicability of the device as an LVAD, showing adequateperformance. Mechanical blood trauma was analyzedthrough 6-h hemolysis tests, with total pressure head of100 mm Hg and flow of 5 L/min. Mean normalized index ofhemolysis was 0.009 g/100 L (±0.002 g/100 L).Studies usinga hybrid cardiovascular simulator were conducted for threetypes of circulatory conditions: normal healthy conditions,concentric hypertrophic heart failure (CHHF), and CHHFwith AABP assistance. Analysis of cardiovascular parametersunder those three conditions demonstrated that whenthe AABP was assisting the system, parameters underCHHF conditions went back to normal healthy values, indicatingthe AABPs effectiveness as CHHF therapy. Ourpreliminary results indicate that it is feasible to use theAABP as a LVAD. The next steps include long-term invivo experiments.