Preparedness for epidemic disease or bioterrorism: minimum cost planning for the location and staffing of urban point-of-dispensing centers.

Urban health authorities in the United States have been charged with developing plans for providing the infrastructure necessary to dispense prophylactic medications to their populations in the case of epidemic disease outbreak or bioterrorist attack. However, no specific method for such plans has been prescribed. This article formulates and demonstrates the use of an integer programming technique for helping to solve a part of the dispensing problem faced by cities, namely that of providing the federally required infrastructure at minimum cost, using their limited time and resources. Specifically, the technique minimizes the number of point-of-dispensing (POD) centers while covering every resident in all the census tracts within the city's jurisdiction. It also determines the optimal staffing requirement in terms of the number of nurses at each POD. This article includes a demonstration of the model using real data from Cleveland, OH, a mid-sized US city. Examples are provided of data and computational results for a variety of input parameter values such as population throughput rate, POD capacities, and distance limitations. The technique can be readily adapted to a wide range of urban areas.

Multilayer gold nanoparticle-assisted protein tryptic digestion in solution and in gel under photothermal heating.

Elevating the reaction temperature is an effective method to accelerate protein enzymatic digestion because it can promote protein denaturation and enzyme activities. In this study, we demonstrated a new photothermal heating method to assist protein tryptic digestion on glass slides. A glass slide coated with layer-by-layer gold nanoparticles (Glass@AuNPs), combined with the use of a near infrared (NIR) diode laser, was used to raise reaction temperature during tryptic digestion in a short period of time. The modified glass slide is capable of absorbing NIR light arising from the dipole-dipole interactions between Au NPs immobilized on the slide. The temperature of Glass@AuNPs rapidly increased when irradiated by the NIR laser, accelerating protein enzymatic digestion conducted on the slide. Thus, when performing the tryptic digestion of proteins on the Glass@AuNPs slide under NIR irradiation, 3.5 min was sufficient to carry out the tryptic digestion of proteins in solution, while less than 5 min was adequate for in-gel tryptic digestion of proteins. Matrix-assisted laser desorption/ionization mass spectrometry was used for characterization of the tryptic digestion product. On the basis of the results, the time taken to analyze proteins could be greatly reduced using this current approach.

A label-free sensing method for phosphopeptides using two-layer gold nanoparticle-based localized surface plasma resonance spectroscopy.

In this study, a new type of localized surface plasmon resonance (LSPR) sensing substrate for phosphopeptides was explored. It has been known that LSPR response for target species is larger in the near-infrared region (NIR) than in the visible region of the electromagnetic spectrum. Several types of noble metal nanoparticles (NPs) with NIR absorption capacities have been previously demonstrated as effective LSPR-sensing nanoprobes. Herein, we demonstrate a straightforward approach with improved sensitivity by simply using layer-by-layer (LBL) spherical Au NPs self-assembled on glass slides as the LSPR-sensing substrates that are responsive in the NIR region of the electromagnetic spectrum. The modified glass slide acquired an LSPR absorption band in the NIR, which resulted from the dipole-dipole interactions between Au NPs. To enable the chip to sense phosphopeptides, the surface of the glass chip was spin-coated with thin titania film (TiO(2)-Glass@Au NPs). Absorption spectrophotometry was employed as a detection tool. Tryptic digest of α-casein was used as a model sample. The feasibility of using the new LSPR approach for detecting a potential risk factor leading to cancers (i.e., phosphorylated fibrinopeptide A) directly from human serum samples was demonstrated. Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) was used to confirm the results.

Multilayer gold nanoparticle-assisted thermal desorption ambient mass spectrometry for the analysis of small organics.

In this study, thermal desorption-based ambient mass spectrometry (TDAMS) for the analysis of small organics was explored. A layer-by-layer (LBL) self-assembled multilayer of a gold nanoparticle (AuNP)-based glass chip (Glass@AuNPs) with the absorption capacity in the near-infrared (NIR) region was used as the energy absorber and as the sample holder for sample deposition at ambient condition. An NIR laser diode (808 nm) was successfully employed as the thermal desorption source to liberate only small molecules from Glass@AuNPs chips. Followed by post-ionization, the resultant ions were monitored by an ion trap mass spectrometer. Post-ionization was assisted by a spray consisting of 50% deionized water-acetonitrile containing 0.1% acetic acid generated from a short tapered capillary by employing a high voltage (4 kV). Analytes with different polarities including small acids, amino acids, insecticides, and biodiesel samples such as ethyl esters can be directly analyzed using this approach. We demonstrated that this ambient mass spectrometric method was suitable for selectively analyzing small target organics directly from complex samples without any sample pretreatment.

Ultrasonication-assisted spray ionization mass spectrometry for the analysis of biomolecules in solution.

In this paper, we describe a novel technique--ultrasonication-assisted spray ionization (UASI)--for the generation of singly charged and multiply charged gas-phase ions of biomolecules (e.g., amino acids, peptides, and proteins) from solution; this method employs a low-frequency ultrasonicator (ca. 40 kHz) in place of the high electric field required for electrospray ionization. When a capillary inlet is immersed into a sample solution within a vial subjected to ultrasonication, the solution is continually directed to the capillary outlet as a result of ultrasonication-assisted capillary action; an ultrasonic spray of the sample solution is emitted at the outlet of the tapered capillary, leading to the ready generation of gas-phase ions. Using an ion trap mass spectrometer, we found that singly charged amino acid and multiply charged peptides/proteins ions were generated through this single-step operation, which is both straightforward and extremely simple to perform. The setup is uncomplicated: only a low-frequency ultrasonicator and a tapered capillary are required to perform UASI. The mass spectra of the multiply charged peptides and proteins obtained from sample solutions subjected to UASI resemble those observed in ESI mass spectra.