Nancy Tawil

Surface plasmon resonance detection of E. coli and methicillin-resistant S. aureus using bacteriophages.

Early diagnosis and appropriate treatment of Escherichia coli (E. coli) O157:H7 and methicillin-resistant Staphylococcus aureus (MRSA) are key elements in preventing resultant life-threatening illnesses, such as hemorrhagic colitis, hemolytic uremic syndrome, and septicemia. In this report, we describe the use of surface plasmon resonance (SPR) for the biodetection of pathogenic bacteria, using bacteriophages as the recognition elements. T4 bacteriophages were used to detect E. coli, while a novel, highly specific phage was used to detect MRSA. We found that the system permits label-free, real-time, specific, rapid and cost-effective detection of pathogens, for concentrations of 10(3) colony forming units/milliliter, in less than 20 min. This system promises to become a diagnostic tool for bacteria that cause major public concern for food safety, bioterrorism, and nosocomial infections.

Protein-Nanoparticle Interactions

In the recent decade, the fabrication of nanoparticles and exploration of their properties have attracted the attention of all branches of science such as physicists, chemists, biologists, engineers, and even medical doctors. Interests for nanoparticles arise from the fact that their mechanical, chemical, electrical, optical, magnetic, electro-optical, and magneto-optical properties of these nanoparticles are completely different from their bulk properties and the predetermined differences are depended on the physicochemical properties of the nanoparticles. There are numerous areas where nanoparticles are of scientific and technological interest, specifically for medical community, where the synthetic and biologic worlds come together and lead to an important concern for design of safe nano-biomaterials. In this chapter, we review and discuss the major biomedical applications of nanoparticles. 1.1 Nanoscience in Medicine Nanomedicine is the application of nanosciences to health and exploits the physical, chemical, and biological properties of nanomaterials. The advent of nanoscience and nanotechnologies is shaping the face of industrial production and economics. As a matter of fact, nano-based products now include electronic components, paint, sports equipment, fabrics, sunscreens, and other cosmetics [1]. However, the most exciting nano-innovations reside in the conception of new medical products such as heart valves, drug-delivery systems, and imaging techniques [1], which will surely obliterate the long-established boundaries amidst chemistry, physics, and biology. It is anticipated that nanotechnology will have substantial economic impacts by encouraging productivity and competitiveness, converging different disciplines of science and technologies, and stimulating education and human development [2]. Experts predict market growth to hundreds of billions of dollars in the next decade. The worldwide market for products exploiting nanotechnology reached M. Rahman et al., Protein-Nanoparticle Interactions, Springer Series in Biophysics 15, DOI 10.1007/978-3-642-37555-2_1,

Nanoparticle and Protein Corona

Nanoparticles and other nanomaterials are increasingly considered for use in biomedical applications such as imaging, drug delivery, and hyperthermic therapies. Thus, understanding the interaction of nanomaterials with biological systems becomes key for their safe and efficient application. It is increasingly being accepted that the surface of nanomaterials would be covered by protein corona upon their entrance to the biological medium. The biological medium will then see the achieved modified surface of nanomaterials, and therefore further cellular/tissue responses depend on the composition of corona. In this chapter, we describe the corona variations according to the physicochemical properties of nanomaterials (e.g., size, shape, surface charge, surface functional groups, and hydrophilicity/hydrophobicity). Besides the nanomaterials’ effects, the role of environment factors, such as protein source and slight temperature variations, is discussed in details.

The differential detection of methicillin-resistant, methicillin-susceptible and borderline oxacillin-resistant Staphylococcus aureus by surface plasmon resonance.

Two hundred fifty Staphylococcus aureus clinical isolates were studied to determine their susceptibilities to β-lactam antibiotics. Among these isolates, 16 were methicillin-sensitive S. aureus (MSSA), 207 were methicillin-resistant S. aureus (MRSA) and 27 were borderline oxacillin-resistant S. aureus (BORSA). Currently, the reported mechanism of methicillin resistance in S. aureus is the production of a distinctive penicillin binding protein 2a (PBP2a), which exhibits low affinity toward β-lactams. A surface plasmon resonance biosensor was evaluated for its ability to identify MRSA and to distinguish these strains from MSSA and BORSA, by specifically detecting PBP2a. We found that the system permits label-free, real-time, specific detection of pathogens for concentrations as low as 10 colony forming units/milliliter (CFU/ml), in less than 20 min. This system promises to become a diagnostic tool for bacteria that cause major public concern in clinical settings.

CMOS Conductometric System for Growth Monitoring and Sensing of Bacteria

We present the design and implementation of a prototype complementary metal-oxide semiconductor (CMOS) conductometric integrated circuit (IC) for colony growth monitoring and specific sensing of Escherichia coli (E. coli) bacteria. The detection of E. coli is done by employing T4 bacteriophages as receptor organisms. The conductometric system operates by measuring the resistance of the test sample between the electrodes of a two-electrode electrochemical system (reference electrode and working electrode). The CMOS IC is fabricated in a TSMC 0.35-μm process and uses a current-to-frequency (I to F) conversion circuit to convert the test sample resistance into a digital output modulated in frequency. Pulsewidth control (one-shot circuit) is implemented on-chip to control the pulsewidth of the output digital signal. The novelty in the current work lies in the ability of the CMOS sensor system to monitor very low initial concentrations of bacteria (4×102 to 4×104 colony forming unit (CFU)/mL). The CMOS system is also used to record the interaction between E. coli and its specific receptor T4 bacteriophage. The prototype CMOS IC consumes an average power of 1.85 mW with a 3.3-V dc power supply.

Protein Corona: Applications and Challenges

The protein corona introduces new unexpected applications and shortcomings for the nanoparticles. For instance, it is now well recognized that the protein coating reduces the targeting capability of surface-engineered nanoparticles by screening the active sites of the targeting ligands. Therefore, in this chapter, we will review the advantages and disadvantages of the protein-nanoparticle interaction with the correspondent biological impact. In addition, broad overview of current available data of both in vitro and in vivo protein-nanoparticle interactions is provided.

Analytical Methods for Corona Evaluations

In order to have deep understanding on the nature and composition of the formed protein corona, one should have adequate information on the available characterization techniques. In this chapter, comprehensive descriptions on the protein corona evaluation methods (e.g., spectroscopy methods (UV/Vis, Raman, fluorescence, mass spectrometry, nuclear magnetic resonance, etc.), dynamic light scattering, circular dichroism, differential centrifugal sedimentation, scanning and transmission electron microscopies, X-ray crystallography, chromatography, etc.) together with their limitations are provided.

The Biological Significance of “Nano”-interactions

In the recent decade, the fabrication of nanoparticles and exploration of their properties have attracted the attention of all branches of science such as physicists, chemists, biologists, engineers, and even medical doctors. Interests for nanoparticles arise from the fact that their mechanical, chemical, electrical, optical, magnetic, electro-optical, and magneto-optical properties of these nanoparticles are completely different from their bulk properties and the predetermined differences are depended on the physicochemical properties of the nanoparticles. There are numerous areas where nanoparticles are of scientific and technological interest, specifically for medical community, where the synthetic and biologic worlds come together and lead to an important concern for design of safe nano-biomaterials. In this chapter, we review and discuss the major biomedical applications of nanoparticles.