Matching Items (5)
Filtering by

Clear all filters

133582-Thumbnail Image.png
Description
Current wound closure technology is limited, and lacks key elements \u2014 such as the formation of an immediate seal \u2014 that could otherwise resolve some of the common and life threatening complications associated with certain surgeries. Previous research has produced nanosealants capable of providing that immediate seal through the use

Current wound closure technology is limited, and lacks key elements \u2014 such as the formation of an immediate seal \u2014 that could otherwise resolve some of the common and life threatening complications associated with certain surgeries. Previous research has produced nanosealants capable of providing that immediate seal through the use of laser activation with a near infrared laser. Here, we have developed a biocompatible suture utilizes the same mechanics to provide the tensile strength needed to replace or supplement existing suture lines. Laser activated tissue integrating sutures (LATIS), are shown to have 75% of the tensile strength of commercially available PGA sutures, while still exhibiting the same laser mediated localized heating effect at power densities of as low as 1.6 W/cm2. LATIS has been shown to reach the temperature ranges needed for protein interdigitation, but suffers from low wet mechanical strength. Preparatory steps or solvents for chemical crosslinking generally dehydrate LATIS sutures, causing a shriveling effect that weakens the overall mechanical strength of the suture. To resolve this, a new method of drying, by which LATIS sutures are dried under tension on a suspended platform, has been shown to decrease control suture strength, but restore the strength of chemically treated LATIS sutures to the level of control sutures or above. These promising results suggest that follow-up work with chemical cross-linkers may produce the increases in LATIS wet strength that are needed for its implementation in deeper tissue surgeries.
ContributorsChang, Andy (Author) / Rege, Kaushal (Thesis director) / Goklany, Sheba (Committee member) / School of Molecular Sciences (Contributor) / Chemical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2018-05
171479-Thumbnail Image.png
Description
The world today needs novel solutions to address current challenges in areas spanning areas from sustainable manufacturing to healthcare, and biotechnology offers the potential to help address some of these issues. One tool that offers opportunities across multiple industries is the use of nonribosomal peptide synthases (NRPSs). These are modular

The world today needs novel solutions to address current challenges in areas spanning areas from sustainable manufacturing to healthcare, and biotechnology offers the potential to help address some of these issues. One tool that offers opportunities across multiple industries is the use of nonribosomal peptide synthases (NRPSs). These are modular biological factories with individualized subunits that function in concert to create novel peptides.One element at the heart of environmental health debates today is plastics. Biodegradable alternatives for petroleum-based plastics is a necessity. One NRPS, cyanophycin synthetase (CphA), can produce cyanophycin grana protein (CGP), a polymer composed of a poly-aspartic acid backbone with arginine side chains. The aspartic backbone has the potential to replace synthetic polyacrylate, although current production costs are prohibitive. In Chapter 2, a CphA variant from Tatumella morbirosei is characterized, that produces up to 3x more CGP than other known variants, and shows high iCGP specificity in both flask and bioreactor trials. Another CphA variant, this one from Acinetobacter baylyi, underwent rational protein design to create novel mutants. One, G217K, is 34% more productive than the wild type, while G163K produces a CGP with shorter chain lengths. The current structure refined from 4.4Å to 3.5Å. Another exciting application of NRPSs is in healthcare. They can be used to generate novel peptides such as complex antibiotics. A recently discovered iterative polyketide synthase (IPTK), dubbed AlnB, produces an antibiotic called allenomycin. One of the modular subunits, a dehydratase named AlnB_DH, was crystallized to 2.45Å. Several mutations were created in multiple active site residues to help understand the functional mechanism of AlnB_DH. A preliminary holoenzyme AlnB structure at 3.8Å was generated although the large disorganized regions demonstrated an incomplete structure. It was found that chain length is the primary factor in driving dehydratase action within AlnB_DH, which helps lend understanding to this module.
ContributorsSwain, Kyle (Author) / Nannenga, Brent (Thesis advisor) / Nielsen, David (Committee member) / Mills, Jeremy (Committee member) / Seo, Eileen (Committee member) / Acharya, Abhinav (Committee member) / Arizona State University (Publisher)
Created2022
Description

Aminoglycosides contain a basic unit of an amino-modified glycoside (sugar) and have potent antibacterial properties used to treat a wide range of bacterial infections, including those that occur in the soft tissue, chest, urinary tract, and endocardial tissue.1, 2 With a broad spectrum of activity and convenient dosing schedule, Aminoglycoside

Aminoglycosides contain a basic unit of an amino-modified glycoside (sugar) and have potent antibacterial properties used to treat a wide range of bacterial infections, including those that occur in the soft tissue, chest, urinary tract, and endocardial tissue.1, 2 With a broad spectrum of activity and convenient dosing schedule, Aminoglycoside helps to effectively fight off Gram-negative bacteria.1, 3 In 1944 an aminoglycoside called streptomycin entered clinical trials to test its effectiveness as an antibiotic.4 After several years other classes of aminoglycosides were discovered such as neomycin, gentamicin, kanamycin, and netilmicin.4 When introduced these antibiotics presented major clinical advancements in the treatment of Tuberculosis and other bacterial infections.3, 4 However their use in modern medicine has diminished due to their toxicity, required parenteral delivery, and the availability of alternative antibiotics.3, 5 The dose-dependent toxicity of aminoglycosides limits their use due to a narrow range of safe aminoglycoside plasma concentrations.3, 5 Exceeding this range in non-target tissues can lead to negative effects on the audio-vestibular apparatus and kidneys.3, 5, 6 In the 1980’s, clinicians began treating infections with antibiotics that were perceived as less toxic and providing broader antibacterial activity.7 This resulted in aminoglycosides being prescribed for more persistent infections that were resistant to other antibiotics.3 With the amount of antibiotic resistant bacteria increasing, many scientists have begun looking into methods for minimizing aminoglycoside toxicity and maximizing its antibacterial activity.3, 8 These methods include encapsulation and polymer conjugation.9, 10 By encapsulating aminoglycosides in liposomes or other vesicles scientists aim to increase its concentration in infected tissues while decreasing nephro- and ototoxicity.9 With conjugated polymers scientists have created polymer complexes containing aminoglycosides and other compounds such as dopamine.11 The goal of these polymers is to limit toxicity by slowing antibiotic release and increasing efficacy of the antibiotic through targeted delivery and toxicity of other compounds.9, 10, 11 Other than its use in treating infections, aminoglycosides are gaining attention as an excellent vehicle for gene delivery.12 In this application aminoglycosides are used to correct a genetic defect by introducing a normal copy of the gene into affected cells.12,13 Currently scientists are assessing aminoglycosides for gene therapy in the treatment of cancer and various other diseases.12, 14 This review will focus on the diverse customizability of aminoglycosides in treating infections and as vehicles for gene therapy.

ContributorsWampler, Cole (Author) / Rege, Kaushal (Thesis director) / Schoepf, Jared (Committee member) / Barrett, The Honors College (Contributor) / Dean, W.P. Carey School of Business (Contributor) / Chemical Engineering Program (Contributor) / School of Life Sciences (Contributor)
Created2023-05
168478-Thumbnail Image.png
Description
Sutures, staples, and tissue glues remain the primary means of tissue approximation and vessel ligation. Laser-activated tissue sealing is an alternative approach that conventionally employs light-absorbing chromophores and nanoparticles for converting near-infrared (NIR) laser to heat. The local increase in temperature engenders interdigitation of sealant and tissue biomolecules, resulting in

Sutures, staples, and tissue glues remain the primary means of tissue approximation and vessel ligation. Laser-activated tissue sealing is an alternative approach that conventionally employs light-absorbing chromophores and nanoparticles for converting near-infrared (NIR) laser to heat. The local increase in temperature engenders interdigitation of sealant and tissue biomolecules, resulting in rapid tissue sealing. Light-activated sealants (LASE) were developed in which indocyanine green (ICG) dye is embedded within a biopolymer matrix (silk or chitosan) for incisional defect repair. Light-activated tissue-integrating sutures (LATIS) that synergize the benefits of conventional suturing and laser sealing were also fabricated and demonstrated higher efficacies for tissue biomechanical recovery and repair in a full-thickness, dorsal surgical incision model in mice compared to commercial sutures and cyanoacrylate skin glue. Localized delivery of modulators of tissue repair, including histamine and copper, from LASE and LATIS further improved healed skin strength. In addition to incisional wounds, histamine co-delivered with silk fibroin LASE films accelerated the closure of full thickness, splinted excisional wounds in immunocompetent BALB/c mice and genetically obese and diabetic db/db mice, resulting in faster closure than Tegaderm wound dressing. Immunohistochemistry analyses showed LASE-histamine treatment enhanced wound repair involving mechanisms of neoangiogenesis, myofibroblast activation, transient epidermal EMT, and also improve healed skin biomechanical strength which are hallmarks of improved healing outcomes. Benefit of temporal delivery was further investigated of a second therapeutic (growth factor nanoparticles) in modulating wound healing outcomes in both acute and diabetic wounds. The hypothesis of temporal delivery of second therapeutic around the ‘transition period’ in wounds further improved wound closure kinetics and biomechanical recovery of skin strength. Laser sealing and approximation, together with delivery of immunomodulatory mediators, can lead to faster healing and tissue repair, thus reducing wound dehiscence, preventing wounds moving towards chronicity and lowering incidence of surgical site infections, all of which can have significant impact in the clinic.
ContributorsGhosh, Deepanjan (Author) / Rege, Kaushal (Thesis advisor) / Acharya, Abhinav (Committee member) / Holloway, Julianne (Committee member) / DiCaudo, David (Committee member) / P. Leung, Kai (Committee member) / Arizona State University (Publisher)
Created2021
157837-Thumbnail Image.png
Description
Tissue approximation and repair have been performed with sutures and staples for centuries, but these means are inherently traumatic. Tissue repair using laser-responsive nanomaterials can lead to rapid tissue sealing and repair and is an attractive alternative to existing clinical methods. Laser tissue welding is a sutureless technique for sealing

Tissue approximation and repair have been performed with sutures and staples for centuries, but these means are inherently traumatic. Tissue repair using laser-responsive nanomaterials can lead to rapid tissue sealing and repair and is an attractive alternative to existing clinical methods. Laser tissue welding is a sutureless technique for sealing incised or wounded tissue, where chromophores convert laser light to heat to induce in tissue sealing. Introducing chromophores that absorb near-infrared light creates differential laser absorption and allows for laser wavelengths that minimizes tissue damage.

In this work, plasmonic nanocomposites have been synthesized and used in laser tissue welding for ruptured porcine intestine ex vivo and incised murine skin in vivo. These laser-responsive nanocomposites improved tissue strength and healing, respectively. Additionally, a spatiotemporal model has been developed for laser tissue welding of porcine and mouse cadaver intestine sections using near-infrared laser irradiation. This mathematical model can be employed to identify optimal conditions for minimizing healthy cell death while still achieving a strong seal of the ruptured tissue using laser welding. Finally, in a model of surgical site infection, laser-responsive nanomaterials were shown to be efficacious in inhibiting bacterial growth. By incorporating an anti-microbial functionality to laser-responsive nanocomposites, these materials will serve as a treatment modality in sealing tissue, healing tissue, and protecting tissue in surgery.
ContributorsUrie, Russell Ricks (Author) / Rege, Kaushal (Thesis advisor) / Acharya, Abhinav (Committee member) / DeNardo, Dale (Committee member) / Holloway, Julianne (Committee member) / Thomas, Marylaura (Committee member) / Arizona State University (Publisher)
Created2019