Variables Affecting the Extraction of Antioxidants in Cold and Hot Brew Coffee: A Review.

Coffee beans are a readily available, abundant source of antioxidants used worldwide. With the increasing interest in and consumption of coffee beverages globally, research into the production, preparation, and chemical profile of coffee has also increased in recent years. A wide range of variables such as roasting temperature, coffee grind size, brewing temperature, and brewing duration can have a significant impact on the extractable antioxidant content of coffee products. While there is no single standard method for measuring all of the antioxidants found in coffee, multiple methods which introduce the coffee product to a target molecule or reagent can be used to deduce the overall radical scavenging capacity. In this article, we profile the effect that many of these variables have on the quantifiable concentration of antioxidants found in both cold and hot brew coffee samples. Most protocols for cold brew coffee involve an immersion or steeping method where the coffee grounds are in contact with water at or below room temperature for several hours. Generally, a higher brewing temperature or longer brewing time yielded greater antioxidant activity. Most studies also found that a lower degree of coffee bean roast yielded greater antioxidant activity.

Quantification of Spent Coffee Ground Extracts by Roast and Brew Method, and Their Utility in a Green Synthesis of Gold and Silver Nanoparticles.

Nanotechnology has become increasingly important in modern society, and nanoparticles are routinely used in many areas of technology, industry, and commercial products. Many species of nanoparticle (NP) are typically synthesized using toxic or hazardous chemicals, making these methods less environmentally friendly. Consequently, there has been growing interest in green synthesis methods, which avoid unnecessary exposure to toxic chemicals and reduce harmful waste. Synthesis methods which utilize food waste products are particularly attractive because they add value and a secondary use for material which would otherwise be disposed of. Here, we show that spent coffee grounds (SCGs) that have already been used once in coffee brewing can be easily used to synthesize gold and silver NPs. SCGs derived from medium and dark roasts of the same bean source were acquired after brewing coffee by hot brew, cold brew, and espresso techniques. The total antioxidant activity (TAC) and total caffeoylquinic acid (CQA) of the aqueous SCG extracts were investigated, showing that hot brew SCGs had the highest CQA and TAC levels, while espresso SCGs had the lowest. SCG extract proved effective as a reducing agent in synthesizing gold and silver NPs regardless of roast or initial brew method.

Effect of surface coating of KYb2F7:Tm(3+) on optical properties and biomedical applications.

This project aims to provide an insight on the effects of biocompatible polymers on the optical properties and the nanoparticle-cell interaction of KYb2F7:Tm(3+) nanocrystals that exhibit strong near infrared (NIR) fluorescence. KYb2F7:Tm(3+) nanocrystals were synthesized with a diameter of 20-30 nm and surface modified with poly(ethylene glycol), Pluronic(®) F-127, and poly(N-vinylpyrrolidone), due to the associated advantages. Some of these include biocompatibility and biodistribution in the instance of agglomeration and hydrophobicity as well as the addition of a targeting agent and drug loading by further functionalization. Despite the decrease in fluorescence intensity induced by the surface modification, thulium's emission fingerprint was easily detected. Moreover, surface modified KYb2F7:Tm(3+) nanocrystals failed to induce a toxic response on endothelial cells following a 24 h uptake period up to concentrations of 100 µg ml(-1). In vitro toxicity and confocal imaging have demonstrated the versatility of these NIR fluorescence nanocrystals in biomedical imaging, drug delivery, and photodynamic therapy.

Depth-Resolved Multispectral Sub-Surface Imaging Using Multifunctional Upconversion Phosphors with Paramagnetic Properties.

Molecular imaging is very promising technique used for surgical guidance, which requires advancements related to properties of imaging agents and subsequent data retrieval methods from measured multispectral images. In this article, an upconversion material is introduced for subsurface near-infrared imaging and for the depth recovery of the material embedded below the biological tissue. The results confirm significant correlation between the analytical depth estimate of the material under the tissue and the measured ratio of emitted light from the material at two different wavelengths. Experiments with biological tissue samples demonstrate depth resolved imaging using the rare earth doped multifunctional phosphors. In vitro tests reveal no significant toxicity, whereas the magnetic measurements of the phosphors show that the particles are suitable as magnetic resonance imaging agents. The confocal imaging of fibroblast cells with these phosphors reveals their potential for in vivo imaging. The depth-resolved imaging technique with such phosphors has broad implications for real-time intraoperative surgical guidance.

Interphotoreceptor retinoid-binding protein protects retinoids from photodegradation.

Retinol degrades rapidly in light into a variety of photoproducts. It is remarkable that visual cycle retinoids can evade photodegradation as they are exchanged between the photoreceptors, retinal pigment epithelium and Müller glia. Within the interphotoreceptor matrix, all-trans retinol, 11-cis retinol and retinal are bound by interphotoreceptor retinoid-binding protein (IRBP). Apart from its role in retinoid trafficking and targeting, could IRBP have a photoprotective function? HPLC was used to evaluate the ability of IRBP to protect all-trans and 11-cis retinols from photodegradation when exposed to incandescent light (0 to 8842 µW cm(-2)); time periods of 0-60 min, and bIRBP: retinol molar ratios of 1:1 to 1:5. bIRBP afforded a significant prevention of both all-trans and 11-cis retinol to rapid photodegradation. The effect was significant over the entire light intensity range tested, and extended to the bIRBP: retinol ratio 1:5. In view of the continual exposure of the retina to light, and the high oxidative stress in the outer retina, our results suggest IRBP may have an important protective role in the visual cycle by reducing photodegradation of all-trans and 11-cis retinols. This role of IRBP is particularly relevant in the high flux conditions of the cone visual cycle.

Accurate Identification and Selective Removal of Rotavirus Using a Plasmonic-Magnetic 3D Graphene Oxide Architecture.

According to the World Health Organization, even in the 21st century, more than one million children die each year due to the rotavirus contamination of drinking water. Therefore, accurate identification and removal of rotavirus are very important to save childrens' lives. Driven by the need, in this Letter, we report for the first time highly selective identification and removal of rotavirus from infected water using a bioconjugated hybrid graphene oxide based three-dimensional (3D) solid architecture. Experimental results show that due to the presence of a high intensity of "hot spots" in the 3D network, an antibody-attached 3D plasmonic-magnetic architecture can be used for accurate identification of rotavirus using surface-enhanced Raman spectroscopy (SERS). Reported data demonstrate that the antibody-attached 3D network binds strongly with rotavirus and is capable of highly efficient removal of rotavirus, which has been confirmed by SERS, fluorescence imaging, and enzyme-linked immunosorbent assay (ELISA) data. We discuss a possible mechanism for accurate identification and efficient removal of rotavirus from infected drinking water.

Optical and spectroscopic properties of human whole blood and plasma with and without Y2O3 and Nd³âº:Y2O3 nanoparticles.

The optical properties of human whole blood and blood plasma with and without Y2O3 and Nd³âº:Y2O3 nanoparticles are characterized in the near infrared region at 808 nm using a double integrating sphere technique. Using experimentally measured quantities of diffuse reflectance and diffuse transmittance, a computational analysis was conducted utilizing the Kubelka-Munk, the Inverse Adding Doubling, and Magic Light Kubelka-Munk and Monte Carlo Methods to determine optical properties of the absorption and scattering coefficients. Room temperature absorption and emission spectra were also acquired of Nd³âº:Y2O3 nanoparticles elucidating their utility as biological markers. The emission spectra of Nd³âº:Y2O3 were taken by exciting the nanoparticles before and after entering the whole blood sample. The emission from the 4F(3/2) → 4I(11/2) manifold transition of Nd³âº:Y2O3 nanoparticles readily propagates through the blood sample at excitation of 808 nm and exhibits a shift in relative intensities of the peaks due to differences in scattering. At 808 nm, in both whole blood and plasma samples, a direct relationship was found with absorption coefficient and Y2O3 nanoparticle concentration. Results for the whole blood indicate a small inverse relationship with Y2O3 nanoparticle concentration and scattering coefficient and in contrast a direct relation for the plasma.

Popcorn-shaped magnetic core-plasmonic shell multifunctional nanoparticles for the targeted magnetic separation and enrichment, label-free SERS imaging, and photothermal destruction of multidrug-resistant bacteria.

Over the last few years, one of the most important and complex problems facing our society is treating infectious diseases caused by multidrug-resistant bacteria (MDRB), by using current market-existing antibiotics. Driven by this need, we report for the first time the development of the multifunctional popcorn-shaped iron magnetic core-gold plasmonic shell nanotechnology-driven approach for targeted magnetic separation and enrichment, label-free surface-enhanced Raman spectroscopy (SERS) detection, and the selective photothermal destruction of MDR Salmonella DT104. Due to the presence of the "lightning-rod effect", the core-shell popcorn-shaped gold-nanoparticle tips provided a huge field of SERS enhancement. The experimental data show that the M3038 antibody-conjugated nanoparticles can be used for targeted separation and SERS imaging of MDR Salmonella DT104. A targeted photothermal-lysis experiment, by using 670 nm light at 1.5 W cm(-2) for 10 min, results in selective and irreparable cellular-damage to MDR Salmonella. We discuss the possible mechanism and operating principle for the targeted separation, label-free SERS imaging, and photothermal destruction of MDRB by using the popcorn-shaped magnetic/plasmonic nanotechnology.

Bimodal Imaging Using Neodymium Doped Gadolinium Fluoride Nanocrystals with Near-Infrared to Near-Infrared Downconversion Luminescence and Magnetic Resonance Properties.

Here we report the synthesis, characterization and application of a multifunctional surface functionalized GdF3:Nd3+ nanophosphor that exhibits efficient near infrared (NIR) fluorescence as well as magnetic properties, which can be utilized for bimodal imaging in medical applications. The nanoparticles are small with an average size of 5 nm and form stable colloids that last for several weeks without settling, enabling the use for several biomedical and photonic applications. Their excellent NIR properties, such as nearly 11 % quantum yield of the 1064 nm emission, make them ideal contrast agents and biomarkers for in vitro and in vivo NIR optical bioimaging. The nanophosphors which were coated with poly(maleic anhydride- alt-1-octadicene) (PMAO) were implemented in cellular imaging and show no significant cellular toxicity for concentrations up to 200 µg ml-1. Furthermore, the incorporation of Gd into the nanocrystalline structure supplies exceptional magnetic properties, making them ideal for use as magnetic resonance imaging (MRI) contrast agents. The utility of these NIR emitting nanoparticles in infrared bioimaging and as contrast agent in magnetic resonance imaging was demonstrated by confocal imaging, magnetic resonance and tissue experiments.

Rare Earth doped nanoparticles in imaging and PDT.

Nanoparticles doped with rare earth ions for biomedical imaging and infrared photodynamic therapy (IRPDT) have been synthesized, characterized, and compared. Specifically, these nanoparticles utilize two primary modalities: near infrared excitation and emission for imaging, and near infrared upconversion for photodynamic therapy. These nanoparticles are optimized for both their infrared emission and upconversion energy transfer to a photoactive agent conjugated to the surface. Finally, these nanoparticles are tested for toxicity, imaged in cells using the near infrared emission pathway, and used for selective killing of cells through the upconversion driven IRPDT.

Effect of Silver Coating on Barium Titanium Oxide Nanoparticle Toxicity.

Nanoparticles are presently being studied for optical and biomedical applications such as medical imaging and drug delivery. Nanoparticles impact the cellular environment due to many variables such as size, shape, and composition. How these factors affect cell viability is not fully understood. The purpose of this study is to test the toxicity effects of silver coating (Ag@) Barium Titanium Oxide (BaTiO3) nanoparticles on Rhesus Monkey Retinal Endothelial cells (RhREC's) in culture. The addition of silver to the nanoparticles increases their nonlinear optical properties significantly, making the Ag@BaTiO3 nanoparticles good candidates for nonlinear microscopy contrast agents. We hypothesize that by silver coating nanoparticles, there will be an increase in cell viability at higher concentrations when compared to non-silver coated nanoparticles. RhREC's were treated with BaTiO3 and Ag@BaTiO3 at concentrations of 0, 1.0, 10.0, and 100µg/ml for 24 hours at 37°C + 5%CO2. After 24 hour incubation with respective nanoparticles, cell viability was determined using the trypan blue dye-exclusion method. Treatment with 0, 1.0 and 10.0µg/ml of Ag@BaTiO3 had minimal effect on cell viability, with 90% viable cells remaining at the end of the 24 hours treatment period. However, cells treated with 100µg/ml of Ag@BaTiO3 resulted in a decrease to 51% viable cells. Comparatively, cells treated with 0, 1.0 and 10µg/ml of BaTiO3 had no significant effect on cell viability (90% viable cells after treatment) while the 100µg/ml treatment resulted in a decrease to 29% viable cells. These results show that silver coating of BaTiO3 nanoparticles has a protective effect on cellular toxicity at high concentrations.

Enhancement of nonlinear optical properties of BaTiO3 nanoparticles by the addition of silver seeds.

Barium titanate (BaTiO3) is a technologically important material because of its nonlinear properties, such as its strong second harmonic generation and high third order susceptibility. While many nonlinear effects have been extensively studied on the bulk scale, there are still questions regarding the strength of nonlinear effects in nanoparticles. The nonlinear properties of BaTiO3 nanoparticles and nanorods have been studied using the closed aperture z-scan technique. Silver was then grown photochemically on the surface of the BaTiO3 nanoparticles, and it was found that the third order susceptibility increases dramatically.

Optical absorption and scattering of bovine cornea, lens, and retina in the near-infrared region.

The optical properties of bovine ocular tissues have been determined at laser wavelengths in the near-infrared (NIR) region. The inverse adding doubling (IAD), Kubelka-Munk (KM), and inverse Monte Carlo (IMC) methods were applied to the measured values of the total diffuse transmission, total diffuse reflection, and collimated transmission to determine the optical absorption and scattering coefficients of the bovine cornea, lens and retina from 750 to 1,000 nm using a CW Ti:sapphire laser. The optical properties obtained from these three methods have been compared and are discussed.

A Comparison of Methods for Determining Optical Properties of Thin Samples.

The near-infrared (NIR) optical properties of human retinal pigmented epithelial (RPE) cells and rare earth nanopowders were studied using a double-integrating sphere setup. The Kubelka-Munk and Inverse Adding-Doubling techniques were applied to obtain absorption and scattering coefficients. These are compared with the coefficients obtained through the Representative Layer Theory described by the Dahm equation. Retinal pigmented epithelial monolayers were cultured from an ARPE19 line in thin cell culture windows, and the nanopowders were pressed into samples of varying thickness. Samples were optically characterized as a function of wavelength. A brief discussion of the shortcomings of existing techniques for computing optical properties when applied to physically thin samples is provided, followed by a comparison between the optical properties of the samples returned by the different techniques.

Optical absorption and scattering of bovine cornea, lens and retina in the visible region.

Optical properties of bovine ocular tissues were determined at laser wavelengths in the visible region. The inverse adding doubling (IAD), Kubelka-Munk (KM), and inverse Monte Carlo (IMC) methods were applied to the measured values of the total diffuse transmission, total diffuse reflection, and collimated transmission to determine the optical absorption and scattering coefficients of the bovine cornea, lens and retina at 457.9 nm, 488 nm, and 514.5 nm laser lines from an argon ion laser. The optical properties obtained from these three methods were compared, and their validity is discussed.