Browse Prior Art Database

Molecular Glue for Highly Controlled Attachment of Macromolecules to Metals

IP.com Disclosure Number: IPCOM000118079D
Original Publication Date: 1996-Sep-01
Included in the Prior Art Database: 2005-Mar-31
Document File: 4 page(s) / 136K

Publishing Venue

IBM

Related People

Biebuyck, H: AUTHOR [+3]

Abstract

Disclosed is a procedure for the covalent attachment of macromolecules to the surface of electrically conductive, semi-conductive or insulating surfaces. The subject is related to the fabrication of hybrid devices (sensors, switches, transducers) that seek to incorporate combinations of solid surfaces and macromolecules in a highly defined manner. The method is controllable and convenient while it avoids problems associated with adventitious, non-specific adsorption of material.

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Molecular Glue for Highly Controlled Attachment of Macromolecules
to Metals

      Disclosed is a procedure for the covalent attachment of
macromolecules to the surface of electrically conductive,
semi-conductive or insulating surfaces.  The subject is related to
the fabrication of hybrid devices (sensors, switches, transducers)
that seek to incorporate  combinations of solid surfaces and
macromolecules in a highly defined manner.  The method is
controllable and convenient while it avoids problems associated with
adventitious, non-specific adsorption of material.

      The applied strategy relies on the synthesis of an organic
molecule, here called PEG-B (Fig. 1a), comprising three functions:
(1) a group that allows its specific attachment to the surface of a
noble metal; (2) a spacer group that provides a barrier between the
solid substrate and its interface with solution thus blocking the
metal, for example, from further reaction; (3) a photoactive group
that allows covalent attachment of molecules present in ordinary,
aqueous buffers (Fig. 1b).

      The first requirement of PEG-B is a chemisorbing head group.
This need is satisfied by thiol, disulfide, isonitrile, or isocyano
groups, any one of which react to form covalent assemblies on noble
metal surfaces; reactive silanes provide chemisorption on surfaces
with a superficial oxide.  Disulfides are particularly useful in this
regard since they represent a largely nonreactive class of
functionality with a high specificity for gold.  These materials are
all well known to allow the self-assembly of their simple alkyl
derivatives into ordered structures up to 5 nm thick on the
appropriate solid surface.

      The second requirement of PEG-B is satisfied by poly(ethylene)
glycols, '(CH' sub 2 'CH' sub 2 'O-)' sub n (PEG), 2 to 20 units
long.  PEG resists, in general, the formation of stable mixed phases
with other materials.  Its solvation structure and self affinity
apparently produce a strong, entropically driven force of repulsion
to materials that seek to incorporate in it.  This tendency is
particularly pronounced  in their behavior with macromolecules like
proteins or DNA: PEGs help partition these materials without causing
their disruption.  When PEGs  of only a few units are incorporated
into thiol containing alkanes adsorbed on gold, deposition of
proteins is completely blocked.  When these PEGs are absent, in
comparison, the presence of the alkane causes  up to 10 nm of protein
to deposit on the supported film by nonspecific,  hydrophobic
interactions with the alkyl backbone.

      The third need of PEG-B is a controllable, covalent attachment
reaction that is general and versatile.  This requirement is
satisfied by benzophenone (BP).  BP is a well known and widely used
cross-linking agent with several advantages over other photosensitive
groups: It is more stable than diazo esters, aryl azides and
diazirines.  It is inert  under ambient lig...