Giorgia Sinibaldi

Bio: Giorgia Sinibaldi is an academic researcher from Sapienza University of Rome. The author has contributed to research in topics: Velocimetry & Jet (fluid). The author has an hindex of 8, co-authored 17 publications receiving 255 citations.

Laser induced cavitation: Plasma generation and breakdown shockwave

Abstract: Laser induced cavitation is one of the effective techniques to generate controlled cavitation bubbles, both for basic study and for applications in different fields of engineering and medicine. Unfortunately, control of bubble formation and symmetry is hardly achieved due to a series of concurrent causes. In particular, the need to focus the laser beam at the bubble formation spot leads, in general, to a conical region proximal to the light source where conditions are met for plasma breakdown. A finite sized region then exists where the electric field may fluctuate depending on several disturbing agents, leading to possible plasma fragmentation and plasma intensity variation. Such irregularities may induce asymmetry in the successive bubble dynamics, a mostly undesired effect if reproducible conditions are sought for. In the present paper, the structure of the breakdown plasma and the ensuing bubble dynamics are analyzed by means of high speed imaging and intensity measurements of the shockwave system launched at breakdown. It is found that the parameters of the system can be tuned to optimize repeatability and sphericity. In particular, symmetric rebound dynamics is achieved almost deterministically when a pointlike plasma is generated at the breakdown threshold energy. Spherical symmetry is also favored by a large focusing angle combined with a relatively large pulse energy, a process which, however, retains a significant level of stochasticity. Outside these special conditions, the elongated and often fragmented conical plasma shape is found to be correlated with anisotropic and multiple breakdown shockwave emission.

Tumor-on-a-chip platforms to study cancer–immune system crosstalk in the era of immunotherapy

Abstract: Immunotherapy is a powerful therapeutic approach able to re-educate the immune system to fight cancer. A key player in this process is the tumor microenvironment (TME), which is a dynamic entity characterized by a complex array of tumor and stromal cells as well as immune cell populations trafficking to the tumor site through the endothelial barrier. Recapitulating these multifaceted dynamics is critical for studying the intimate interactions between cancer and the immune system and to assess the efficacy of emerging immunotherapies, such as immune checkpoint inhibitors (ICIs) and adoptive cell-based products. Microfluidic devices offer a unique technological approach to build tumor-on-a-chip reproducing the multiple layers of complexity of cancer-immune system crosstalk. Here, we seek to review the most important biological and engineering developments of microfluidic platforms for studying cancer-immune system interactions, in both solid and hematological tumors, highlighting the role of the vascular component in immune trafficking. Emphasis is given to image processing and related algorithms for real-time monitoring and quantitative evaluation of the cellular response to microenvironmental dynamic changes. The described approaches represent a valuable tool for preclinical evaluation of immunotherapeutic strategies.

Reversible Cavitation-Induced Junctional Opening in an Artificial Endothelial Layer.

Abstract: Targeting pharmaceuticals through the endothelial barrier is crucial for drug delivery. In this context, cavitation-assisted permeation shows promise for effective and reversible opening of intercellular junctions. A vessel-on-a-chip is exploited to investigate and quantify the effect of ultrasound-excited microbubbles-stable cavitation-on endothelial integrity. In the vessel-on-a-chip, the endothelial cells form a complete lumen under physiological shear stress, resulting in intercellular junctions that exhibit barrier functionality. Immunofluorescence microscopy is exploited to monitor vascular integrity following vascular endothelial cadherin staining. It is shown that microbubbles amplify the ultrasound effect, leading to the formation of interendothelial gaps that cause barrier permeabilization. The total gap area significantly increases with pressure amplitude compared to the control. Gap opening is fully reversible with gap area distribution returning to the control levels 45 min after insonication. The proposed integrated platform allows for precise and repeatable in vitro measurements of cavitation-enhanced endothelium permeability and shows potential for validating irradiation protocols for in vivo applications.

Corrigendum: Sound Packing DNA: packing open circular DNA with low-intensity ultrasound

Abstract: Scientific Reports 5: Article number: 984610.1038/srep09846; published online: April202015; updated: October052015

High-resolution, long-term characterization of bacterial motility using optical tweezers

Abstract: We present a single-cell motility assay, which allows the quantification of bacterial swimming in a well-controlled environment, for durations of up to an hour and with a temporal resolution greater than the flagellar rotation rates of ∼100 Hz. The assay is based on an instrument combining optical tweezers, light and fluorescence microscopy, and a microfluidic chamber. Using this device we characterized the long-term statistics of the run-tumble time series in individual Escherichia coli cells. We also quantified higher-order features of bacterial swimming, such as changes in velocity and reversals of swimming direction.

Experimental Study of Quadcopter Acoustics and Performance at Static Thrust Conditions

Abstract: A quadcopter, DJI Phantom II, was tested in the Virginia Tech Anechoic Chamber to study its aeroacoustics performance. Noise and thrust measured by a single microphone and a load cell were acquired for 4 different rotor configurations, two plastic and two carbon fiber rotors. To study the effects of multi-rotor interaction, the quadcopter was also set to operate with 1, 2 and 4 rotors. Results of 4-rotor operation show that tones at the blade passing frequency, shaft rate and their harmonics dominate the quadcopter acoustic spectrum up to 6000 Hz without much deterioration. Also significant is a broadband hump present in the mid frequency range which increases over 10 dB above the broadband level at low frequencies. Motor noise is also noticeable in the mid frequency range. For a smallscaled rotor, thrust performance is greatly influenced by rotor configuration whereas its acoustic signature is only altered near mid and high frequencies resulting in 1-2 dB change in the OASPL for the same thrust setting. Having 1, 2 or 4 rotors operating does not affect the acoustic signature but a significant increase was found in broadband noise when switching from 2 non-adjacent rotors to 4 rotors.