Biomedical Engineering and Bioengineering Commons^™

Engineering Stimuli-Responsive Polymeric Nanoassemblies: Rational Designs For Intracellular Delivery Of Biologics, Kingshuk Dutta

Doctoral Dissertations

Biologic drugs have gained enormous research attention in recent years as reflected by the development of multiple candidates to the clinical pipelines and an increased percentage of FDA approval. This is reasoned by the fact that biologics have been proven to deliver more predictive and promising benefits for many hard-to-cure diseases by ‘drugging the undruggable’ targets. However, the challenges associated with biologic drug development are multi-fold, viz, poor encapsulation efficacy, systemic instability, low cellular internalization and endosomal escape capability. Thus, it is essential to develop new molecular strategies that can not only address the associated drug delivery challenges, but also …

3-D Fabry–Pérot Cavities Sculpted On Fiber Tips Using A Multiphoton Polymerization Process, Jonathan W. Smith, Jeremiah C. Williams, Joseph S. Suelzer, Nicholas G. Usechak, Hengky Chandrahalim

Faculty Publications

This paper presents 3-D Fabry–Pérot (FP) cavities fabricated directly onto cleaved ends of low-loss optical fibers by a two-photon polymerization (2PP) process. This fabrication technique is quick, simple, and inexpensive compared to planar microfabrication processes, which enables rapid prototyping and the ability to adapt to new requirements. These devices also utilize true 3-D design freedom, facilitating the realization of microscale optical elements with challenging geometries. Three different device types were fabricated and evaluated: an unreleased single-cavity device, a released dual-cavity device, and a released hemispherical mirror dual-cavity device. Each iteration improved the quality of the FP cavity's reflection spectrum. The …

Single‐Molecule 3d Orientation Imaging Reveals Nanoscale Compositional Heterogeneity In Lipid Membranes, Jin Lu, Hesam Mazidi, Tianben Ding, Oumeng Zhang, Matthew D. Lew

Electrical & Systems Engineering Publications and Presentations

In soft matter, thermal energy causes molecules to continuously translate and rotate, even in crowded environments, thereby impacting the spatial organization and function of most molecular assemblies, such as lipid membranes. Directly measuring the orientation and spatial organization of large collections (>3000 molecules μm⁻²) of single molecules with nanoscale resolution remains elusive. In this paper, we utilize SMOLM, single‐molecule orientation localization microscopy, to directly measure the orientation spectra (3D orientation plus “wobble”) of lipophilic probes transiently bound to lipid membranes, revealing that Nile red's (NR) orientation spectra are extremely sensitive to membrane chemical composition. SMOLM images resolve …

Near Simultaneous Laser Scanning Confocal And Atomic Force Microscopy (Conpokal) On Live Cells, Joree N. Sandin, Surya P. Aryal, Thomas E. Wilkop, Christopher I. Richards, Martha E. Grady

Physiology Faculty Publications

Techniques available for micro- and nano-scale mechanical characterization have exploded in the last few decades. From further development of the scanning and transmission electron microscope, to the invention of atomic force microscopy, and advances in fluorescent imaging, there have been substantial gains in technologies that enable the study of small materials. Conpokal is a portmanteau that combines confocal microscopy with atomic force microscopy (AFM), where a probe "pokes" the surface. Although each technique is extremely effective for the qualitative and/or quantitative image collection on their own, Conpokal provides the capability to test with blended fluorescence imaging and mechanical characterization. Designed …

Optimized Xanthene-Based Probes For Pancreatic Cancer Imaging, Ian Ruramai Munhenzva

Dissertations and Theses

Pancreatic Ductal Adenocarcinoma (PDAC) is one of the deadliest human malignancies with an extremely poor 5-year survival rate of below 5%. Surgical resection is the most effective treatment of choice because chemotherapy and radiation therapy do not improve life expectancy. Residual tumor after PDAC surgery is common due to a lack of PDAC targeted intraoperative contrast agents to confirm clear margins.

Fluorescence imaging has the potential to improve surgery outcome and PDAC patients' survival rate via the use of highly PDAC-specific molecular probes to facilitate tumor identification. This thesis describes the application of a focused library of benzoxanthene fluorophores for …

Dose Response Effect Of Mycobacterium Smegmatis-Derived Lipomannan In Raw 264.7 Murine Macrophages, Cassandra Robertson

Undergraduate Theses and Capstone Projects

Tuberculosis is a debilitating respiratory disease caused by the bacterial species Mycobacterium tuberculosis, which acts by infecting the host’s macrophages and evading their immune responses. The purpose of the study was to determine if RAW 264.7 murine macrophage activity could be facilitated and intensified by stimulation with LAM from M. smegmatis. Stimulation with bacterial LAM, and lipopolysaccharide (LPS) as a positive control, yields functional endpoints: nitric oxide (NO) production measured by nitrites (NO2) in the culture supernatant and expression of proteins, such as tumor necrosis factor-α and inducible nitric oxide synthase (iNOS). RAW 264.7 cells were stimulated dose-responsively with LAM …

Probing Nanoelectroporation And Resealing Of The Cell Membrane By The Entry Of Ca2+ And Ba2+ Ions, Wenfei Bo, Mantas Silkunas, Uma Mangalanathan, Vitalij Novickij, Maura Casciola, Iurii Semenov, Shu Xiao, Olga N. Pakhomova, Andrei G. Pakhomov

Bioelectrics Publications

The principal bioeffect of the nanosecond pulsed electric field (nsPEF) is a lasting cell membrane permeabilization, which is often attributed to the formation of nanometer-sized pores. Such pores may be too small for detection by the uptake of fluorescent dyes. We tested if Ca²⁺, Cd²⁺, Zn²⁺, and Ba²⁺ ions can be used as nanoporation markers. Time-lapse imaging was performed in CHO, BPAE, and HEK cells loaded with Fluo-4, Calbryte, or Fluo-8 dyes. Ca²⁺ and Ba²⁺ did not change fluorescence in intact cells, whereas their entry after nsPEF increased fluorescence within <1 ms. The threshold for one 300-ns pulse was at 1.5–2 kV/cm, much lower than >7 …

Gravity-Drawing Flexible Silicone Filaments As Fiber Optics And Model Foldamers, Katherine Snell

CMC Senior Theses

Here, we present a method of gravity-drawing polydimethylsiloxane (PDMS) silicone fibers with application as fiber optics and as model foldamers. Beginning as a viscous liquid, PDMS is cured using heat until its measured viscosity reaches 4000 mPa•s. The semi-cured elastomer is then extruded through a tube furnace to produce thin (diameters on the order of hundred micrometers) filaments with scalable lengths. PDMS is biocompatible, gas-permeable, flexible, and hydrophobic. Additionally, the PDMS surface hydrophobicity can be modified via UV exposure, O2 plasma, and corona discharge. We demonstrate the patternibility (i.e patterns of hydrophobicity) of PDMS fibers, adding complexity to potential foldamer …