Periodontal diseases are prevalent worldwide and are linked to numerous other health conditions due to dysbiosis and chronic inflammatory state. Most periodontal diseases are caused by pathogenic bacteria that colonize dental tissues in the form of biofilm. Eradication of bacterial biofilms can be difficult to achieve due to the complex architecture of the teeth and gums which complicates the removal. Orthodontic wires and dental devices introduce additional hurdles to the adequate removal of biofilms by traditional methods since mechanical disruption via direct contact with toothbrush bristles, floss, and abrasive toothpaste is limited. Magnetically activated nanoparticles (NPs), specifically iron oxide nanoparticles (IONPs) that can be functionalized as antimicrobial particles and remotely controlled by magnetic fields, are of interest for oral biofilm eradication. We present data in multi-species bacterial cultures, established biofilms, human gingival keratinocytes, and human gingival fibroblast cells alone and in the presence of multispecies biofilm co-cultures to determine the safest, most efficacious IONP size ranges and treatment concentrations of active magnetic NPs for removal of dental biofilms. We report enhanced efficacy for IONPs coated with alginate vs. dextran, and small sizes (~8 nm vs. >20 nm in size) appear to exhibit enhanced antimicrobial efficacy. Human gingival keratinocyte (TIGK) cells in co-culture with treated and untreated multispecies biofilms in an in-vitro periodontitis model also exhibited a trend of reduced inflammatory markers in wells with IONP-treated biofilms.
Over the years, an increase in mass plastic production has caused growing concerns about the adverse effects that plastic nanoparticles (NPs) in the environment may have on human health. There are many knowledge gaps regarding the effects that NPs have on human health. Accurate studies prove challenging due to the hurdles in obtaining reliable model particles, performing accurate in vitro toxicology assessments, and visualizing results accurately. Numerous studies published in peer-reviewed literature have used commercially available NPs to represent environmental nanoplastic pollution. The commercial NPs with fluorescent tags were often used since they are easy to be monitored in cellular and organismal studies. However, the legitimacy of these commercial NP products has been questioned due to concerns about surface modifications altering interactions at the nano-bio interfaces, and the possibility that surface-bound fluorophores may detach and result in optical artifacts. Additionally, polystyrene is not the only polymer that should be investigated. We synthesized an orange, fluorescent organic dye and incorporated the dye into PMMA NPs to investigate skin cell uptake and in vivo biodistribution in a fish embryo model. We also compare the uptake results with that of the commonly used polystyrene particles and discuss possible mechanisms of uptake. Results revealed that 1) PMMA NPs can pass into embryos and potentially accumulate in larval bodies, and 2) commercially available sulfate-modified NPs and PMMA NPs accumulate similarly in fluorescently labeled fibroblast cells, however, PMMA NPs accumulate more localized intracellularly.
Pseudomonas aeruginosa is among the top three leading causative opportunistic human pathogens, possessing one of the largest bacterial genomes and an exceptionally large proportion of regulatory genes therein. It has been known for more than a decade that the size and complexity of the P. aeruginosa genome is responsible for the adaptability and resilience of the bacteria to include its ability to resist many disinfectants and antibiotics. We have investigated the susceptibility of P. aeruginosa bacterial biofilms to iron oxide (magnetite) nanoparticles (NPs) with and without attached drug (tobramycin). We also characterized the susceptibility of zero-valent iron NPs, which are known to inactivate microbes. The particles, having an average diameter of 16 nm were capped with natural alginate, thus doubling the hydrodynamic size. Nanoparticle-drug conjugates were produced via cross-linking drug and alginate functional groups. Drug conjugates were investigated in the interest of determining dosage, during these dosage-curve experiments, NPs unbound to drug were tested in cultures as a negative control. Surprisingly, we found that the iron oxide NPs inhibited bacterial growth, and thus, biofilm formation without the addition of antibiotic drug. The inhibitory dosages of iron oxide NPs were investigated and the minimum inhibitory concentrations are presented. These findings suggest that NP-drug conjugates may overcome the antibiotic drug resistance common in P. aeruginosa infections.
Pseudomonas aeruginosa bacterium is a deadly pathogen, leading to respiratory failure in cystic fibrosis and nosocomial pneumonia, and responsible for high mortality rates in these diseases. P. aeruginosa has inherent as well as acquired resistance to many drug classes. In this paper, we investigate the effectiveness of two classes; aminoglycoside (tobramycin) and fluoroquinolone (ciprofloxacin) administered alone, as well as conjugated to iron oxide (magnetite) nanoparticles. P. aeruginosa possesses the ability to quickly alter its genetics to impart resistance to the presence of new, unrecognized treatments. As a response to this impending public health threat, we have synthesized and characterized magnetite nanoparticles capped with biodegradable short-chain carboxylic acid derivatives conjugated to common antibiotic drugs. The functionalized nanoparticles may carry the drug past the mucus and biofilm layers to target the bacterial colonies via magnetic gradient-guided transport. Additionally, the magnetic ferrofluid may be used under application of an oscillating magnetic field to raise the local temperature, causing biofilm disruption, slowed growth, and mechanical disruption. These abilities of the ferrofluid would also treat multi-drug resistant strains, which appear to be increasing in many nosocomial as well as acquired opportunistic infections. In this in vitro model, we show that the iron oxide alone can also inhibit bacterial growth and biofilm formation.
Colloidal quantum dots (QDs) are of interest for a variety of biomedical applications, including bioimaging, drug
targeting, and photodynamic therapy. However, a significant limitation is that highly efficient photoluminescent QDs
available commercially contain cadmium. Recent research has focused on cadmium-free QDs, which are anticipated to
exhibit significantly lower cytotoxicity. Previous work has focused on InP and ZnO as alternative semiconductor
materials for QDs. However, these nanoparticles have been shown to be cytotoxic. Recently, we have synthesized high
quantum efficiency (exceeding 90%), color tunable MnSe/ZnSeS nanoparticles, as potentially attractive QDs for
biomedical applications. Additionally, the manganese imparts magnetic properties on the QDs, which are important for
magnetic field-guided transport, hyperthermia, and potentially magnetic resonance imaging (MRI). The QDs can be
further biofunctionalized via conjugation to a ligand or a biomarker of disease, allowing combination of drug delivery
with visual verification and colocalization due to the color tunability of the QDs.
Cystic fibrosis (CF) is an inherited childhood-onset life-shortening disease. It is characterized by increased respiratory
production, leading to airway obstruction, chronic lung infection and inflammatory reactions. The most common bacteria
causing persisting infections in people with CF is Pseudomonas aeruginosa. Superparamagnetic Fe3O4 iron oxide
nanoparticles (NPs) conjugated to the antibiotic (tobramycin), guided by a gradient of the magnetic field or subjected to
an oscillating magnetic field, show promise in improving the drug delivery across the mucus and P. aeruginosa biofilm
to the bacteria. The question remains whether tobramycin needs to be released from the NPs after the penetration of the
mucus barrier in order to act upon the pathogenic bacteria. We used a zero-length 1-ethyl-3-[3-dimethylaminopropyl]
carbodiimide hydrochloride (EDC) crosslinking agent to couple tobramycin, via its amine groups, to the carboxyl groups
on Fe3O4 NPs capped with citric acid. The therapeutic efficiency of Fe3O4 NPs attached to the drug versus that of the
free drug was investigated in P. aeruginosa culture.
Lanthanide fluoride colloidal nanocrystals offer a way to improve the diagnosis and treatment of cancer through the
enhanced absorption of ionizing radiation, in addition to providing visible luminescence. In order to explore this
possibility, tests with a kilovoltage therapy unit manufactured by the Universal X-Ray Company were performed to
estimate the energy sensitivity of this technique. La0.2Ce0.6Eu0.2F3 nanocrystals capped with polyethylene glycol of
molecular weight 6000 were synthesized, suspended in deionized water, and made tolerant to biological ionic pressures
by incubation with fetal bovine serum. These nanocrystals were characterized by dynamic light scattering, muffle
furnace ashing, and photoluminescence spectroscopy. Clonogenic assays were performed on the cells to assay the
cytotoxicity and radiotoxicity of the nanocrystals on the human pancreatic cancer cell line PANC-1, purchased from
ATCC.
Iron oxide colloidal nanoparticles (ferrofluids) are investigated for application in the treatment of cystic fibrosis lung
infections, the leading cause of mortality in cystic fibrosis patients. We investigate the use of iron oxide nanoparticles to
increase the effectiveness of administering antibiotics through aerosol inhalation using two mechanisms: directed
particle movement in the presence of an inhomogeneous static external magnetic field and magnetic hyperthermia.
Magnetic hyperthermia is an effective method for decreasing the viscosity of the mucus and biofilm, thereby enhancing
drug, immune cell, and antibody penetration to the affected area. Iron oxide nanoparticles of various sizes and
morphologies were synthesized and tested for specific losses (heating power). Nanoparticles in the superparamagnetic to
ferromagnetic size range exhibited excellent heating power. Additionally, iron oxide / zinc selenide core/shell
nanoparticles were prepared, in order to enable imaging of the iron oxide nanoparticles. We also report on synthesis and
characterization of MnSe/ZnSeS alloyed quantum dots.
Naturally occurring dysprosium is attractive as a neutron detector because of its high thermal neutron capture cross
section and high natural abundance. Neutron-induced transmutation of 164Dy results in production of stable isotopes of
holmium and erbium (the latter only at sufficiently high neutron fluxes), due to beta decays caused by nucleus
instability. This mechanism, unaffected by gamma radiation, can be used to unambiguously detect neutrons, without
having to discriminate against an accompanying gamma flux. Optically-enabled thermal neutron detection can be based
on significant differences in optical properties of Dy and Ho or Er, which allows to determine the relative fractions of
Dy, and Ho, and E in an irradiated sample. In our search for the most sensitive method of differentiating between Dy and
Ho residing in the same host material, we produced various Dy- and Ho-containing nanocrystals and uniformly dispersed
them in a PMMA polymer matrix. Optical properties of the nanocomposites were analyzed by means of absorption and
PL spectroscopy. We also report on neutron irradiation experiments with Dy-containing nanocrystals and our attempts to
optically detect neutron-induced conversion of Dy into Ho.
Iron oxide colloidal nanocrystals (ferrofluids) are investigated for application in the treatment of cystic fibrosis lung
infections, the leading cause of mortality in cystic fibrosis patients. We investigate the use of iron oxide nanocrystals to
increase the effectiveness of inhalation aerosol antibiotics therapy through two mechanisms: directed particle movement
in the presence of a static external magnetic field and magnetic hyperthermia. Magnetic hyperthermia is an effective
method for decreasing the viscosity of the mucus and biofilm thereby increasing drug, immune cell, and antibody
penetration to the affected area. Iron oxide nanocrystals of various sizes and morphologies were synthesized and tested
for specific losses (heating power) using frequencies of 111.1 kHz and 629.2 kHz, and corresponding magnetic field
strengths of 9 and 25 mT. Nanocrystals in the superparamagnetic to ferromagnetic size range exhibited excellent heating
power. Additionally, iron oxide-zinc selenide core-shell nanoparticles were prepared in parallel in order to allow
imaging of the iron oxide nanoparticles.
Lanthanide fluoride colloidal nanocrystals offer a way to improve the diagnosis and treatment of cancer through the
enhanced absorption of ionizing radiation, as well as providing visible luminescence. In order to explore this possibility,
cytotoxicity assays need to be performed on mammalian cells in vitro, to show minimum levels of biocompatibility for
future experiments. 20% lanthanum 60% cerium and 20% europium lanthanide fluoride nanocrystals were capped with
polyethylene glycol (PEG) of molecular weight 4000 and suspended in deionized water. These nanocrystals were
characterized by transmission electron microscopy, muffle furnace ashing, absorbance spectroscopy, dynamic light
scattering, and photoluminescence spectroscopy. Visible light microscopy and trypan blue staining was performed on the
cells to assay the cytotoxicity of the nanocrystal on the human astrocytoma line U-87 MG, purchased from ATCC.
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