Research Terms
Life Sciences Biochemistry Physical Sciences Chemistry
Keywords
Research Interest ?Polyelectrolytes with opposite charges associate into complexes or coacervates. As thin films, these complexes control surface properties including bioadhesion. Coacervates, found in nature as membraneless organelles in cells, are held together by multiple “sticky” charge-charge interactions. This special type of attraction can be moderated by salt (“saloplasticity”) providing unprecedented control over the materials properties of this fascinating form of amorphous condensed matter.
Dr. Schlenoff has developed "Thirsty Saloplastics", polyelectrolyte complexes that efficiently dry solvents down to the parts-per-million level. Many small-scale and industrial-scale processes require the use of solvents or gases absent of water, as "wet" or "humid" reagents may produce undesirable reactions or may even be corrosive. There is a need for drying agents which absorb even trace amounts of water, can be reactivated at low temperatures for re-use, and have high water capacity. Dr. Schlenoff's polyelectrolyte complexes (PECs) dries solvents at a level comparable to commercially available adsorbents and are non-toxic and easy to produce. PECs are prepared by mixing solutions of positive and negative polyelectrolytes; the resulting powder can be readily extruded to form a tougher more efficient material.
The proposed invention describes methods of producing, in one pot, iron oxide nanoparticles of total diameter less than 10 nm bearing a stabilizing shell of zwitterion and associated compositions. The synthesis of zwitterated iron oxide nanoparticles was achieved by a modified Massart method by the addition of sulfobetaine siloxane either post-synthesis or before co-precipitation of iron salts (in situ). The particles are precipitated in the presence of a zwitterion siloxane which caps the particles and stabilizes them as soon as they are made.
This fine tuning finds mass applications in data storage, catalysis, and in biotechnology and medicine. Detection, cell sorting, and diagnosis using iron oxide nanoparticles have been reported. However, their potential use as contrast agents in magnetic resonance imaging (MRI) or as magnetic fluids for hyperthermia treatment continues to be the driving force for their miniaturization and surface chemistry manipulation. The particles obtained using this new method are super stable and small enough to be excreted so that they do not remain in circulation after the imaging is finished.
The demand for medical wound dressings is universal. Ranging in use from treating minor cuts to traumatic injuries, medical wound dressings prevent infections and save lives. In the case of traumatic injury, current wound dressings often require the application of a variety of materials, such as a combination of wound-filling gels, gauze, tape, and splints. However, Dr. Schlenoff’s research and discovery of saloplastics can decrease the number of necessary materials needed since saloplastic dressings can treat multiple aspects of a wound.
The process of creating saloplastics uses salt instead of heat to melt plastics made from blends of charged polymers. By placing layers of positively and negatively charged electrolytes on top of one another, their electrical charges cancel each other out and create a neutrally charged, ultrathin film. These ultra-thin polymer coatings are useful for producing biocompatible surfaces that can be implanted into the human body for medical purposes.
Approximately 750,000 Americans suffer strokes each year. Worldwide, that number increases to 20 million people. Primary stroke damage occurs from blood clotting and secondary damage occurs when toxic byproducts, including hemin, are produced from the trauma experienced during a stroke. This condition, known as hemin toxicity, leads to cell damage and cell death that in turn may cause irreparable brain damage or death for the individual.
With Dr. Schlenoff’s research, stents used for implantation inside coronary arteries during surgical procedures could be coated with an ultrathin film that prevents cells and proteins from adhering, thus avoiding a narrowing of the arteries and restriction of blood flow.
With modern advancements in the integrated circuit industry, Chemical Mechanilcal Planarization (CMP) has been widely adopted for high-precision fabrication processes. CMP creates a nearly-perfect flat surface on a silicon wafer by using mechanical polishing and a chemical slurry to remove unwanted conductive and dielectric materials.
Two chief problems commonly faced by users of CMP are the tendency of the nanoparticles within the chemical slurry to agglomerate and the adherence of these particles to the surface of the wafer. Dr. Schlenoff has developed a silica nanoparticle with a modified surface that is well suited for these challenges. Importantly, these abrasive nanoparticles form stable suspensions. They resist aggregation or agglomeration without the need for surfactant additives and the additional steps required to remove the resulting residue. Additionally, they demonstrate minimal adhesion to the wafer surface.
