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We present here a highly efficient sensor for bacteria that provides an olfactory output, allowing detection without the use of instrumentation, and with a modality that does not require visual identification. The sensor platform uses nanoparticles to reversibly complex and inhibits lipase. These complexes are disrupted in the presence of bacteria, restoring enzyme activity and generating scent from odorless pro-fragrance substrate molecules. This system provides rapid (15 min) sensing and very high sensitivity (102 cfu/mL) detection of bacteria using the human sense of smell as an output.

Endoscopic retrograde cholangiopancreatography (ERCP) is an endoscopic technique developed to allow access to the pancreaticobiliary system. Many individuals have contributed to the development of ERCP into the diagnostic and therapeutic tool that it is today. With the development of better imaging modalities, the indications for strictly diagnostic ERCP are shrinking; however, ERCP techniques are used for a widening variety of therapeutic interventions. Indications for ERCP range from treatment of benign conditions such as choledocholithiasis and sphincter of Oddi dysfunction to treatment of malignant strictures and advanced techniques such as radiofrequency ablation. Careful patient selection and technique is necessary to minimize the risk profile of the procedure. Those performing ERCP should be aware of the risks and complications as well as their treatment. Techniques utilizing ERCP will likely continue to expand in the future, making it a useful minimally invasive tool for the treatment of many diseases of patients.

Acute diverticulitis is a common condition that has been increasing in incidence in the United States. It is associated with increasing age, but the pathophysiology of acute diverticulitis is still being elucidated. It is now believed to have a significant contribution from inflammatory processes rather than being a strictly infectious process. There are still many questions to be answered regarding the optimal management of acute diverticulitis because recent studies have challenged traditional practices, such as the routine use of antibiotics, surgical technique, and dietary restrictions for prevention of recurrence.

In this paper we describe the use of a temperature-responsive polymer to regulate DNA interactions in both a DNA-mediated assembly system and a DNA-encoded drug delivery system. A thermoresponsive pNIPAAm-co-pAAm polymer, with a transition temperature (TC) of 51 °C, was synthesized with thiol modification and grafted onto gold nanoparticles (Au NPs) also containing single-stranded oligonucleotides (ssDNA). The thermoresponsive behavior of the polymer regulated the accessibility of the sequence-specific hybridization between complementary DNA-functionalized Au NPs. At TTC, the polymer was hydrophilic and extended, blocking interaction between the complementary sequences at the periphery of the hydrodynamic diameter. In contrast, at TTC, the polymer shell undergoes a hydrophilic to -phobic phase transition and collapses, shrinking below the outer ssDNA, allowing for the sequence-specific hybridization to occur. The potential application of this dynamic interface for drug delivery is shown, in which the chemotherapy drug doxorubicin (DOX) is bound to double-stranded DNA (dsDNA)-functionalized Au NPs whose sequences are known to be high-affinity intercalation points for it. The presence of the polymer capping is shown to decrease drug release kinetics and equilibrium at TTC, but increase release at TTC, thus improving the cytotoxicity of the encoded nanocarrier design.

We study the gravitational sedimentation of citrate- or ascorbate-capped spherical gold nanoparticles (AuNP) by measuring the absorption-vs.-time curve produced as the particles sediment through the optical beam of a spectrophotometer, and comparing the results with a calculated sedimentation curve. TEM showed the AuNP had gold-core diameters of 12.1±0.6, 65.0±5.2, 82.5±5.2 or 91.8±6.2 nm, and gave diameter distribution histograms. The Mason-Weaver sedimentation-diffusion equation was solved for various particle diameters and the solutions were weighted with the TEM histogram and the size-dependent extinction coefficient, for comparison with absorbance-vs.-time curve obtained from freshly prepared suspensions of the AuNP. For particles having average gold-core diameters of 12.1±0.6, 65.0±5.2 and 82.5±5.2 nm, very good agreement exists between the theoretical and observed curves, showing that the particles sediment individually and that the diameter of the gold core is the important factor controlling sedimentation. For the largest particles, observed and calculated curves generally agree, but the former shows random effects consistent with non-homogeneous domains in the sample. Unlike TEM, the simple and unambiguous sedimentation experiment detects all the particles in the sample and can in principle be used to derive the true size histogram. It avoids artifacts of TEM sampling and shear forces of ultracentrifugation. We also show how information about the size histogram can be obtained from the sedimentation curve.

Gel electrophoresis is a powerful tool in gold nanoparticle (AuNP) research. While the technique is sensitive to the size, charge, and shape of particles, its optimal performance requires a relatively large amount of AuNP in the loading wells for visible detection of bands. We here describe a novel and more sensitive method for detecting AuNPs in agarose gels that involves staining the gel with the common organic fluorophore fluorescein, to produce AuNP band intensities that are linear with nanoparticle concentration and almost an order of magnitude larger than those obtained without staining the gel.

In this report we describe the synthesis, characterization, and cytotoxic properties of DNA-capped gold nanoparticles having attached folic acid (FA), a thermoresponsive polymer (p), and/or poly(ethylene glycol) (PEG) oligomers that could be used to deliver the anticancer drug doxorubicin (DOX) in chemotherapy. The FA-DNA oligomer used in the construction of the delivery vehicle was synthesized through the reaction of the isolated folic acid N-hydroxysuccinimide ester with the amino-DNA and the conjugated DNA product was purified using high performance liquid chromatography (HPLC). This approach ultimately allowed control of the amount of FA attached to the surface of the delivery vehicle. Cytotoxicity studies using SK-N-SH neuroblastoma cells with drug loaded delivery vehicles were carried out using a variety of exposure times (1-48 h) and recovery times (1-72 h), and in order to access the effects of varying amounts of attached FA, in culture media deficient in FA. DOX loaded delivery vehicles having 50% of the DNA strands with attached FA were more cytotoxic than when all of the strands contained FA. Since FA stimulates cell growth, the reduced cytotoxicity of vehicles fully covered with FA suggests that the stimulatory effects of FA can more than compensate for the cytotoxic effects of the drug on the cell population. While attachment of hexa-ethylene glycol PEG(18) to the surface of the delivery vehicle had no effect on cytotoxicity, 100% FA plus the thermoresponsive polymer resulted in IC50 = 0.48 ± 0.01 for an exposure time of 24 h and a recovery time of 1 h, which is an order of magnitude more cytotoxic than free DOX. Confocal microscopic studies using fluorescence detection showed that SK-N-SH neuroblastoma cells exposed to DOX-loaded vehicles have drug accumulation inside the cell and, in the case of vehicles with attached FA and thermoresponsive polymer, the drug appears more concentrated. Since the biological target of DOX is DNA, the latter observation is consistent with the high cytotoxicity of vehicles having both FA and the thermoresponsive polymer. The study highlights the potential of DNA-capped gold nanoparticles as delivery vehicles for doxorubicin in cancer chemotherapy.

Sedimentation curves of gold nanoparticles in water were obtained by measuring the optical density of a suspension over time. The results are not subject to sampling errors, and refer to the particles in situ. Curves obtained simultaneously at several wave lengths were analyzed together to derive the size histogram of the sedimenting particles. The bins in the histogram were 5 nm wide and centered at diameters 60, 65, …, 110 nm. To get the histogram, we weighted previously calculated solutions to the Mason–Weaver sedimentation–diffusion equation for various particle diameters with absorption/scattering coefficients and size (diameter) abundances { c j }, and found the { c j } which gave the best fit to all the theoretical sedimentation curves. The effects of changing the number of bins and the wave lengths used were studied. Going to smaller bins would mean determining more parameters and require more wave lengths. The histograms derived from sedimentation agreed quite well in general with the histogram derived from TEM. Differences found for the smallest particle diameters are partly due to statistical fluctuations (TEM found only 1–2 particles out of 103 with these diameters). More important is that the TEM histogram indicates 12% of the particles have diameters of 75 ± 2.5 nm, and the sedimentation histogram shows none. We show that this reflects the difference between the particles in situ, which possess a low-density shell about 1 nm thick, and the bare particles on the TEM stage. Correcting for this makes agreement between the two histograms excellent. Comparing sedimentation-derived with TEM-derived histograms thus shows differences between the particles in situ and on the TEM stage.

This study assessed concentrations and investigated potential source regions for PCBs, PBDEs, and organochlorine pesticides in Acadia National Park, Maine, USA. Back-trajectories and potential source contribution function (PSCF) values were used to map potential source areas for total-PCBs, BDE-47, and 10 organochlorine pesticides. The constructed PSCF maps showed that ANP receives high pollutant concentrations in air masses that travel along four main pathways: (1) from the SW along the eastern Atlantic seaboard, (2) from the WSW over St. Louis, and Columbus regions, (3) from the west over Chicago, and Toronto regions, and (4) from WNW to NNW over the Great Lakes, and Quebec regions. Transport of all studied pollutants were equally distributed between the first three pathways, with only minor contributions from the last pathway. This study concludes that the high-pollutant concentrations arriving at ANP do not exclusively originate from the major urban centers along the eastern Atlantic seaboard.

Oligonucleotide-functionalized gold nanoparticles (AuNP) were designed and synthesized to be delivery vehicles for the clinically used anticancer drugs doxorubicin (DOX) and actinomycin D (ActD). Each vehicle contains a tailorable number of DNA duplexes, each possessing three high-affinity sequences for the intercalation of either DOX or ActD, thus allowing for control of drug loading. Drug binding was evaluated by measuring changes to DNA melting temperature, T(m), hydrodynamic diameter, D(h), and surface plasmon resonance wavelength, λ(spr), with drug loading. These studies indicate that DOX intercalates at its high-affinity sequence bound at the AuNP, and that ActD exhibits relatively weaker binding to its preferred sequence. Agarose gel electrophoresis further confirmed drug binding and revealed that particle mobilities inversely correlate with D(h). The equilibrium binding constant, K, and dissociation rate constant, β, were determined by dialysis. Results indicate that the high negative electrostatic potential within the DNA shell of the particle significantly decreases β and enhances K for DOX but has little effect on K and β for ActD. The cytotoxicity of the vehicles was studied, with IC(50) = 5.6 ± 1.1 μM and 46.4 ± 9.3 nM for DOX-DNA-AuNP and IC(50) = 0.12 ± 0.07 μM and 0.76 ± 0.46 nM for ActD-DNA-AuNP, in terms of drug and particle concentrations, respectively.

The anticancer drug, doxorubicin (DOX), was loaded onto DNA-capped gold nanoparticles (AuNP) designed for specific DOX intercalation. Drug binding was confirmed by monitoring DNA melting temperature, AuNP plasmon resonance maximum, and hydrodynamic radius increase, as a function of [DOX]/[DNA] ratio. The capacity for drug release to target DNA was confirmed.