Fluorescence characterization of clinically-important bacteria

Healthcare-associated infections (HCAI/HAI) represent a substantial threat to patient health during hospitalization and incur billions of dollars additional cost for subsequent treatment. One promising method for the detection of bacterial contamination in a clinical setting before an HAI outbreak occurs is to exploit native fluorescence of cellular molecules for a hand-held, rapid-sweep surveillance instrument. Previous studies have shown fluorescence-based detection to be sensitive and effective for food-borne and environmental microorganisms, and even to be able to distinguish between cell types, but this powerful technique has not yet been deployed on the macroscale for the primary surveillance of contamination in healthcare facilities to prevent HAI. Here we report experimental data for the specification and design of such a fluorescence-based detection instrument. We have characterized the complete fluorescence response of eleven clinically-relevant bacteria by generating excitation-emission matrices (EEMs) over broad wavelength ranges. Furthermore, a number of surfaces and items of equipment commonly present on a ward, and potentially responsible for pathogen transfer, have been analyzed for potential issues of background fluorescence masking the signal from contaminant bacteria. These include bedside handrails, nurse call button, blood pressure cuff and ward computer keyboard, as well as disinfectant cleaning products and microfiber cloth. All examined bacterial strains exhibited a distinctive double-peak fluorescence feature associated with tryptophan with no other cellular fluorophore detected. Thus, this fluorescence survey found that an emission peak of 340nm, from an excitation source at 280nm, was the cellular fluorescence signal to target for detection of bacterial contamination. The majority of materials analysed offer a spectral window through which bacterial contamination could indeed be detected. A few instances were found of potential problems of background fluorescence masking that of bacteria, but in the case of the microfiber cleaning cloth, imaging techniques could morphologically distinguish between stray strands and bacterial contamination

Nanotechnology in Head and Neck Cancer: The Race Is On

Rapid advances in the ability to produce nanoparticles of uniform size, shape, and composition have started a revolution in the sciences. Nano-sized structures herald innovative technology with a wide range of potential therapeutic and diagnostic applications. More than 1000 nanostructures have been reported, many with potential medical applications, such as metallic-, dielectric-, magnetic-, liposomal-, and carbon-based structures. Of these, noble metallic nanoparticles are generating significant interest because of their multifunctional capacity for novel methods of laboratory-based diagnostics, in vivo clinical diagnostic imaging, and therapeutic treatments. This review focuses on recent advances in the applications of nanotechnology in head and neck cancer, with special emphasis on the particularly promising plasmonic gold nanotechnology

Semiconductor Quantum Dots for Biomedicial Applications

Semiconductor quantum dots (QDs) are nanometre-scale crystals, which have unique photophysical properties, such as size-dependent optical properties, high fluorescence quantum yields, and excellent stability against photobleaching. These properties enable QDs as the promising optical labels for the biological applications, such as multiplexed analysis of immunocomplexes or DNA hybridization processes, cell sorting and tracing, in vivo imaging and diagnostics in biomedicine. Meanwhile, QDs can be used as labels for the electrochemical detection of DNA or proteins. This article reviews the synthesis and toxicity of QDs and their optical and electrochemical bioanalytical applications. Especially the application of QDs in biomedicine such as delivering, cell targeting and imaging for cancer research, and in vivo photodynamic therapy (PDT) of cancer are briefly discussed

Integrin αvβ3-targeted gold nanoshells augment tumor vasculature-specific imaging and therapy

Huan Xie1, Parmeswaran Diagaradjane2, Amit A Deorukhkar2, Beth Goins3, Ande Bao3, William T Phillips3, Zheng Wang4, Jon Schwartz5, Sunil Krishnan21Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, Texas Southern University, Houston, TX, USA; 2Department of Radiation Oncology, Division of Radiation Oncology, the University of Texas MD Anderson Cancer Center, Houston, TX, USA; 3Department of Radiology, the University of Texas Health Science Center at San Antonio (UTHSC-San Antonio), San Antonio, TX, USA; 4MPI Research, Inc., Mattawan, MI, USA; 5Nanospectra Biosciences, Inc., Houston, TX, USAPurpose: Gold nanoshells (NSs) have already shown great promise as photothermal actuators for cancer therapy. Integrin αvβ3 is a marker that is specifically and preferentially overexpressed on multiple tumor types and on angiogenic tumor neovasculature. Active targeting of NSs to integrin αvβ3 offers the potential to increase accumulation preferentially in tumors and thereby enhance therapy efficacy.Methods: Enzyme-linked immunosorbent assay (ELISA) and cell binding assay were used to study the in vitro binding affinities of the targeted nanoconjugate NS–RGDfK. In vivo biodistribution and tumor specificity were analyzed using 64Cu-radiolabeled untargeted and targeted NSs in live nude rats bearing head and neck squamous cell carcinoma (HNSCC) xenografts. The potential thermal therapy applications of NS–RGDfK were evaluated by subablative thermal therapy of tumor xenografts using untargeted and targeted NSs.Results: ELISA and cell binding assay confirmed the binding affinity of NS–RGDfK to integrin αvβ3. Positron emission tomography/computed tomography imaging suggested that tumor targeting is improved by conjugation of NSs to cyclo(RGDfK) and peaks at ~20 hours postinjection. In the subablative thermal therapy study, greater biological effectiveness of targeted NSs was implied by the greater degree of tumor necrosis.Conclusion: The results presented in this paper set the stage for the advancement of integrin αvβ3-targeted NSs as therapeutic nanoconstructs for effective cancer therapy.Keywords: nanoparticle, cyclo(RGDfK), cancer, thermal ablatio

In-vivo pharmacokinetics of δ-ALA induced PPIX during photodynamic therapy on mice tumor model

In the recent years (delta) -aminolevulinic acid ((delta) -ALA) a precursor for the endogenous production of protoporphyrin IX (PPIX) has gained importance in the Photodynamic Therapy (PDT) of superficial and early-stage cancers. Though (delta) -ALA is present naturally in the cells, systemic administration of exogenous (delta) -ALA leads to the production of intracellular endogenous PP IX in both the tumor and the normal cells, but with varying concentration. However, the PPIX is accumulated more in the tumor tissues as the fast growing tumor cells take up the administered (delta) -ALA more than the normal cells. As the therapeutic efficacy of PDT is dependent on the post (delta) -ALA incubation time, at which the tumor to normal ratio of the PPIX concentration is high, the concentration of the PPIX in the normal and the tumor site were estimated using fluorescence spectroscopy. However, the estimation of the PPIX concentration during/after PDT is mandatory, as the PDT dosimetry is dependent on the sensitizer concentration at the target of interest. The observed variation in the concentration of PPIX in the tumor site with respect to the unexposed normal surrounding tissues, may be attributed to the diffusion of PPIX from the surrounding normal tissues to the tumor site, across the concentration gradient. Based on this a mathematical model has been proposed, to estimate the rate parameter for the diffusion of PPIX from the surrounding normal tissues in to the tumor tissue (K<SUB>m</SUB>), due to photobleaching during PDT at two different fluence. The K<SUB>m</SUB> value at two different fluences, 57.6 and 36 J/cm2 are estimated as 5.444+/- 1.186 and 3.221+/- 0.957, respectively. Further, the rate parameter for the cleavage and efflux of (delta) -ALA (K1), and the rate parameter for the evasion of the PPIX from the tumor tissues during PDT (Kt), were also estimated by fitting the experimental data to the developed mathematical model. The estimated parameters will be utilized to estimate the exact concentration of PPIX in the tumor tissues for a better PDT efficacy

Near-infrared narrow-band imaging of gold/silica nanoshells in tumors

textGold nanoshells (GNS) are a new class of nanoparticles that can be optically tuned to scatter or absorb light from the near-ultraviolet to near-infrared (NIR) region by varying the core (dielectric silica) /shell (gold) ratio. In addition to spectral tunability, GNS are inert and bioconjugatable making them potential labels for in vivo imaging and therapy of tumors. We report the use of GNS as exogenous contrast agents for enhanced visualization of tumors using narrow band imaging (NBI). NBI takes advantage of the strong NIR absorption of GNS to distinguish between blood and nanoshells in the tumor by imaging in narrow wavelength bands in the visible and NIR, respectively. Using tissue-simulating phantoms, we determined the optimum wavelengths to enhance contrast between blood and GNS. We then used the optimum wavelengths for ex-vivo imaging of tumors extracted from human colon cancer xenograft bearing mice injected with GNS. Systemically delivered GNS accumulated passively in tumor xenografts by enhanced permeability and retention (EPR) effect. Ex-Vivo NBI of tumor xenografts demonstrated tumor specific heterogeneous distribution of GNS with a clear distinction from the tumor vasculature. The results of the present study demonstrate the feasibility of using GNS as contrast agents to visualize tumor tissues using NBI technique.Biomedical Engineerin

Validation of PTV margin for Gamma Knife Icon frameless treatment using a PseudoPatient® Prime anthropomorphic phantom

The Gamma Knife Icon allows the treatment of brain tumors mask-based single-fraction or fractionated treatment schemes. In clinic, uniform axial expansion of 1 mm around the gross tumor volume (GTV) and a 1.5 mm expansion in the superior and inferior directions are used to generate the planning target volume (PTV). The purpose of the study was to validate this margin scheme with two clinical scenarios: (a) the patient’s head remaining right below the high-definition motion management (HDMM) threshold, and (b) frequent treatment interruptions followed by plan adaptation induced by large pitch head motion. A remote-controlled head assembly was used to control the motion of a PseudoPatient® Prime head phantom; for dosimetric evaluations, an ionization chamber, EBT3 films, and polymer gels were used. These measurements were compared with those from the Gamma Knife plan. For the absolute dose measurements using an ionization chamber, the percentage differences for both targets were less than 3.0% for all scenarios, which was within the expected tolerance. For the film measurements, the two-dimensional (2D) gamma index with a 2%/2 mm criterion showed the passing rates of ≥87% in all scenarios except the scenario 1. The results of Gel measurements showed that GTV (D100) was covered by the prescription dose and PTV (D95) was well above the planned dose by up to 5.6% and the largest geometric PTV offset was 0.8 mm for all scenarios. In conclusion, the current margin scheme with HDMM setting is adequate for a typical patient’s intrafractional motion. © 2020 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals LLC on behalf of American Association of Physicists in Medicine