Capillary electrophoresis-mass spectrometry methods for tryptic peptide mapping of therapeutic antibodies

Tryptic peptide mapping is routinely used in the biotech industry to confirm primary sequence, cell line stability, and to analyze posttranslational modifications. Peptide analysis is generally done by reverse phase liquid chromatography with UV or mass spectrometric detection. This method provides excellent resolution and sequence coverage. However, traditional methods are slow, and generally cannot detect small, hydrophilic peptides due to coelution with the column void volume. In this work, complementary CE-MS peptide analysis methods have been developed. The analyses are performed on a traditional CE-MS instrument with a sheath interface, and also on a novel sheathless interface that promises improved resolution and limit of detection. The methods were performed on a tryptic digest of a therapeutic monoclonal antibody for which LC-MS detects 97% sequence coverage. The 3% not covered consists of 11 peptides containing three amino acids or fewer, including two in the critical complementarity binding domain. Without further processing, the same tryptic digest was analyzed by CE-MS. Separation and detection of the 11 small peptides was achieved on CE-MS systems with both interfaces. The sheathless system produced better peak capacity and gave mass spectra with significantly less noise, while the sheath system proved to have better repeatability.     

Annoyance due to railway vibration at different times of the day

The time of day when vibration occurs is considered as a factor influencing the human response to vibration. The aim of the present paper is to identify the times of day during which railway vibration causes the greatest annoyance, to measure the differences between annoyance responses for different time periods and to obtain estimates of the time of day penalties. This was achieved using data from case studies comprised of face-to-face interviews and internal vibration measurements (N=755). Results indicate that vibration annoyance differs with time of day and that separate time of day weights can be applied when considering exposure-response relationships from railway vibration in residential environments.     

Lab on Fiber Technology for biological sensing applications

This review presents an overview of “Lab on Fiber” technologies and devices with special focus on the design and development of advanced fiber optic nanoprobes for biological applications. Depending on the specific location where functional materials at micro and nanoscale are integrated, “Lab on Fiber Technology” is classified into three main paradigms: Lab on Tip (where functional materials are integrated onto the optical fiber tip), Lab around Fiber (where functional materials are integrated on the outer surface of optical fibers), and Lab in Fiber (where functional materials are integrated within the holey structure of specialty optical fibers). This work reviews the strategies, the main achievements and related devices developed in the “Lab on Fiber” roadmap, discussing perspectives and challenges that lie ahead, with special focus on biological sensing applications.

     

A New Strong-Acid Free Route to Produce Xanthan Gum-PANI Composite Scaffold Supporting Bioelectricity

Conductive hybrid xanthan gum (XG)–polyaniline (PANI) biocomposites forming 3D structures able to mimic electrical biological functions are synthesized by a strong-acid free medium. In situ aniline oxidative chemical polymerizations are performed in XG water dispersions to produce stable XG–PANI pseudoplastic fluids. XG–PANI composites with 3D architectures are obtained by subsequent freeze-drying processes. The morphological investigation highlights the formation of porous structures; UV–vis and Raman spectroscopy characterizations assess the chemical structure of the produced composites. I–V measurements evidence electrical conductivity of the samples, while electrochemical analyses point out their capability to respond to electric stimuli with electron and ion exchanges in physiological-like environment. Trial tests on prostate cancer cells evaluate biocompatibility of the XG–PANI composite. Obtained results demonstrate that a strong acid-free route produces an electrically conductive and electrochemically active XG–PANI polymer composite. The investigation of charge transport and transfer, as well as of biocompatibility properties of composite materials produced in aqueous environments, brings new perspective for exploitation of such materials in biomedical applications. In particular, the developed strategy can be used to realize biomaterials working as scaffolds that require electrical stimulations for inducing cell growth and communication or for biosignals monitoring and analysis.