Multiview optical resolution photoacoustic microscopy

Optical resolution photoacoustic microscopy (OR-PAM), while providing high lateral resolution, has been limited by its relatively poor acoustically determined axial resolution. Although this limitation has been tackled in recent works by using either broadband acoustic detection or nonlinear photoacoustic effects, a flexible solution with three-dimensional optical resolution in reflection mode remains desired. Herein we present a multiview OR-PAM technique. By imaging the sample from multiple view angles and reconstructing the data using a multiview deconvolution method, we have experimentally demonstrated an isotropic optical resolution in three dimensions

An array of simple, fast, and safe approaches to visualizing fine cellular structures in free-hand sections of stem, leaf, and fruit using optical microscopy

A wide array of free-hand-sectioning-based optical microscopy techniques that are simple, safe, and inexpensive, yet allows quick and easy identification of specific cell types and cellular components with unprecedented resolution are presented using leaf (Saintpaulia ionantha and Schefflera actinophylla), stem (Vitis vinifera and V. labruscana), and fruit (Vitis vinifera) tissues.  The objective of this study was to generate contrast and capture high quality cellular images of various plant organs either via infusing basic fuchsin, a xylemic dye into organs or using naturally pigmented organs by employing the classic technique of free-hand sectioning.  Also, images were obtained via post-staining free-hand sections of organs without any dye infusion.  Leaves injected with dye revealed its strikingly regular and hierarchical reticulate venation structure.  The free-hand sections of healthy and water-stressed leaf petioles, and stems and pedicels prepared from organs either infused with basic fuchsin or post-stained with safranin displayed exceptional cellular details.  These included the xylic and phloic transport systems positioned around the central parenchymatous pith, their tissue pattern in each system, and occlusion of xylem vessels by the parenchymatous tissues (tylosis).  The free-hand sections of fruit revealed fine details of its translucent mesocarp embedded with vasculature of varied architecture, and seed morphology.  Free-hand sections of naturally chromated petioles illustrated its internal structure pertaining to anthocyanin accumulating cells and crystals in superb details, and particularly, the most visually spectacular images of trichomes.  Since observations of internal structures of plants constitute the foundations of plant biology, the microscopy techniques illustrated in this study can be of great interest and benefit to both addressing fundamental questions in plant biology and curiosity-driven research

Biofilm Prevention on 3D Printed Surfaces for Biomedical Applications

Biofilms are complex communities of bacteria residing within an exopolysaccharide matrix that adheres to a surface, such as medical devices and implants, causing chronic infections. Due to the antibiotic resistant nature of biofilms, the use of antibiotics alone is ineffective for treating biofilm-related infections. Hydrophilicity plays an important role in surface attachment because the first step for biofilm formation is bacterial adhesion to a surface and biofilm is less likely to form on hydrophilic surfaces. In this thesis, biofilm formation inhibition of Staphylococcus aureus on 3D printed modified surfaces was investigated. Modifications included: treatment of polylactic acid and thermoplastic polyurethane filaments with polyethylene glycol and castor oil, as well as surface polishing. Samples were tested for wettability by the contact angle method and surface changes were analyzed microscopically. Wettability of treated samples increased, except for polished thermoplastic polyurethane. All samples were decontaminated before the microbiological assays were performed. Four decontamination methods were tested (immersion in 70% ethanol for 15 minutes only and combined with vortex, autoclavation and ultraviolet germicidal irradiation). Autoclaving was an efficient sterilization method; however, this process affected the surface of the samples. Ultraviolet germicidal irradiation was an optimum decontamination step. Biofilm growth inhibition was analyzed through the resazurin method. Four out of six treated samples inhibited biofilm formation at different levels. Polished thermoplastic polyurethane and polished polylactic acid samples inhibited biofilm formation by 47% (± 6) and 33% (±36), respectively. Polylactic acid-polyethylene glycol had the most significant antibiofilm property by reducing biofilm formation by 52% (±5), followed by 22% (±12) in polylactic acid-castor oil. Based on these preliminary data, polished surfaces and filaments treatment with polyethylene glycol showed promising results for biofilm inhibition