The University of Maryland University College is an American public university located in the unincorporated community of Adelphi in Prince George's County, Maryland in the United States. It is known primarily for its distance learning classes and programs, but UMUC also offers classes on campus at its Academic Center in Largo, and at satellite campuses across the Baltimore-Washington Metropolitan Area, throughout Maryland, as well as in Europe, the Middle East, and Asia. UMUC serves over 90,000 students worldwide and is one of the largest distance learning institutions in the world. UMUC is open to all applicants with a 100 percent acceptance rate for undergraduate programs. The university offers 120 academic programs in instructor-led and online classes, including bachelor, masters, and doctoral degrees as well as undergraduate and graduate certificates. UMUC is a member of the University System of Maryland, which includes eleven separate public universities in Maryland. Wikipedia.
Isaacs L.,University of Maryland University College
Accounts of Chemical Research | Year: 2014
ConspectusThis Account focuses on stimuli responsive systems that function in aqueous solution using examples drawn from the work of the Isaacs group using cucurbit[n]uril (CB[n]) molecular containers as key recognition elements. Our entry into the area of stimuli responsive systems began with the preparation of glycoluril derived molecular clips that efficiently distinguish between self and nonself by H-bonds and π-π interactions even within complex mixtures and therefore undergo self-sorting. We concluded that the selectivity of a wide variety of H-bonded supramolecular assemblies was higher than previously appreciated and that self-sorting is not exceptional behavior. This lead us to examine self-sorting within the context of CB[n] host-guest chemistry in water.We discovered that CB[n] homologues (CB and CB) display remarkably high binding affinity (Ka up to 1017 M-1) and selectivity toward their guests, which renders CB[n]s prime components for the construction of stimuli responsive host-guest systems. The CB ·adamantaneammonium ion complex, which is particularly privileged (K a = 4.2 × 1012 M-1), was introduced by us as a stimulus to trigger constitutional changes in multicomponent self-sorting systems. For example, we describe how the free energy associated with the formation of host-guest complexes of CB[n]-type receptors can drive conformational changes of included guests like triazene-arylene foldamers and cationic calixarenes, as well as induced conformational changes (e.g., ammonium guest size dependent homotropic allostery, metal ion triggered folding, and heterochiral dimerization) of the hosts themselves.Many guests display large pKa shifts within their CB[n]-guest complexes, which we used to promote pH controlled guest swapping and thermal trans-to-cis isomerization of azobenzene derivatives. We also used the high affinity and selectivity of CB toward its guests to outcompete an enzyme (bovine carbonic anhydrase) for a two-faced inhibitor, which allowed stimuli responsive regulation of enzymatic activity. These results prompted us to examine the use of CB[n]-type receptors in both in vitro and in vivo biological systems. We demonstrated that adamantaneammonium ion can be used to intracellularly sequester CB from gold nanoparticles passivated with hexanediammonium ion·CB complexes and thereby trigger cytotoxicity. CB derivatives bearing a biotin targeting group enhance the cytotoxicity of encapsulated oxaliplatin toward L1210FR cells. Finally, acyclic CB[n]-type receptors function as solubilizing excipients for insoluble drugs for drug delivery purposes and as a broad spectrum reversal agent for the neuromuscular blocking agents rocuronium, vecuronium, and cis-atracurium in rats. The work highlights the great potential for integration of CB[n]-type receptors with biological systems. © 2014 American Chemical Society. Source
Vedernikov A.N.,University of Maryland University College
Accounts of Chemical Research | Year: 2012
A tom economy and the use of "green" reagents in organic oxidation, including oxidation of hydrocarbons, remain challenges for organic synthesis. Solutions to this problem would lead to a more sustainable economy because of improved access to energy resources such as natural gas. Although natural gas is still abundant, about a third of methane extracted in distant oil fields currently cannot be used as a chemical feedstock because of a dearth of economically and ecologically viable methodologies for partial methane oxidation. Two readily available "atom-economical" "green" oxidants are dioxygen and hydrogen peroxide, but few methodologies have utilized these oxidants effectively in selective organic transformations. Hydrocarbon oxidation and C-H functionalization reactions rely on Pd II and Pt II complexes. These reagents have practical advantages because they can toleratemoisture and atmospheric oxygen. But this tolerance for atmospheric oxygen also makes it challenging to develop novel organometallic palladium and platinumcatalyzed C-H oxidation reactions utilizing O 2 or H 2O 2. This Account focuses on these challenges: the development of M-C bond (M = Pt II, Pd II) functionalization and related selective hydrocarbon C-H oxidations with O 2 or H 2O 2. Reactions discussed in this Account do not involve mediators, since the latter can impart low reaction selectivity and catalyst instability. As an efficient solution to the problem of directM-C oxidation and functionalization with O 2 and H 2O 2, this Account introduces the use of facially chelating semilabile ligands such as di(2-pyridyl)methanesulfonate and the hydrated form of di(2-pyridyl)ketone that enable selective and facile M II-C(sp n) bond functionalization with O 2 (M = Pt, n = 3; M = Pd, n =3(benzylic)) or H 2O 2 (M = Pd,n = 2). The reactions proceed efficiently in protic solvents such as water, methanol, or acetic acid. With the exception of benzylic Pd II complexes, the organometallic substrates studied form isolable high-valent Pt IV or Pd IV intermediates as a result of an oxidant attack at theM II atom. The resulting high-valentM IV intermediates undergo C-O reductive elimination, leading to products in high yields. Guidelines for the synthesis of products containing other Pd III bonds (X = OAc, Cl, Br) while using O 2 or H 2O 2 as oxidants are also discussed. Although the M II-C bond functionalization reactions including high-valent intermediates are well understood, the mechanism for the aerobic functionalization of benzylic Pd II complexes will require a more detailed exploration. Importantly, further optimization of the systems suitable for stoichiometric M II-C bond functionalization led to the development of catalytic reactions, including selective acetoxylation of benzylic C-H bonds with O 2 as the oxidant and hydroxylation of aromatic C-H bonds with H 2O 2 in acetic acid solutions. Both reactions proceed efficiently with substrates that contain a directing heteroatom. This Account also describes catalytic methods for ethylene dioxygenation with H 2O 2 using M II complexes supported by facially chelating ligands. Mechanistic studies of these new oxidation reactions point to important ways to improve their substrate scope and to develop "green" CH functionalization chemistry. © 2011 American Chemical Society. Source
University of Maryland University College and U.S. Army | Date: 2015-07-21
A sensor system, and a method of detecting a target analyte, comprises a chemically functionalized block copolymer, and a target analyte. The block copolymer exhibits a color change in the visible spectrum upon exposure to the target analyte.
University of Maryland University College | Date: 2015-09-29
Provided are hybrid biomaterials comprising one or more layers of cross-linked poly(propylene fumarate) and/or cross-linked copolymer comprising a plurality of cross-linked propylene fumarate moieties. The layers may further comprise a plurality of microparticles, a plurality of micropores, or both a plurality of microparticles and a plurality of micropores encapsulated within the cross-linked poly(propylene fumarate) and/or cross-linked copolymer comprising a plurality of cross-linked propylene fumarate moieties. One of the layers is disposed on a compliant matrix dense tissue substrate (e.g., a pericardium tissue substrate). The hybrid biomaterials can be used, for example, in method of repairing tissue defects.
University of Maryland University College | Date: 2015-07-08
The present invention relates to methods of treating or preventing a bacterial disease or infection, antibacterial compositions, and antibacterial surfaces, including isolated endolysin polypeptides from bacteriophage GRCS.