Hydrogels that degrade under appropriate conditions of pH and temperature by virtue of crosslinking compounds that cleave through an elimination reaction are described. The hydrogels may be used for delivery of various agents, such as pharmaceuticals.

Hydrogels that degrade under appropriate conditions of pH and temperature by virtue of crosslinking compounds that cleave through an elimination reaction are described. The hydrogels may be used for delivery of various agents, such as pharmaceuticals.

The present invention relates to linker molecules of formula (1), X-T.sub.b-V.sub.a—U—Y—Z (1) and a method for purifying peptides using said linker molecules. The linker molecule can be coupled to a purification resin via the moiety X and to a peptide via the moiety Y under the release of the leaving group Z. T is an optional spacer moiety and V is an optional electron withdrawing moiety. U is an aryl or 5- or 6-membered heteroaryl moiety bound to at least one electron withdrawing moiety V, W or E. The linker is stable under acidic conditions and releases the peptide upon addition of a reducing agent.

Hydrogels that degrade under appropriate conditions of pH and temperature by virtue of crosslinking compounds that cleave through an elimination reaction are described. The hydrogels may be used for delivery of various agents, such as pharmaceuticals.

Provided is a compound having the structure:

(SIG)-(SI-MOD).sub.m

where SIG is a signaling molecule, SI is a self-immolative structure bound to SIG such that SIG has a reduced signal relative to the signal of SIG without SI, MOD is a moiety bound to SI that is subject to modification by an activator, and m is an integer from 1 to about 10. When MOD is modified by an activator, SI is destabilized and self-cleaved from SIG such that SIG generates an increased signal. Also provided are methods of determining whether a sample, such as a cell, comprises an activator, such as a nitroreducase, using the compound. Further provided are methods of determining whether a mammalian cell is hypoxic using the compound where nitroreductase is the activator. A method of detecting a microorganism that comprises a nitroreductase using the compound where nitroreductase is the activator is also provided.

The present invention provides diacylhydrazine ligands and chiral diacylhydrazine ligands for use with ecdysone receptor-based inducible gene expression systems. Thus, the present invention is useful for applications such as gene therapy, large scale production of proteins and antibodies, cell-based screening assays, functional genomics, proteomics, metabolomics, and regulation of traits in transgenic organisms, where control of gene expression levels is desirable. An advantage of the present invention is that it provides a means to regulate gene expression and to tailor expression levels to suit the user's requirements.

The present invention provides diacylhydrazine ligands and chiral diacylhydrazine ligands for use with ecdysone receptor-based inducible gene expression systems. Thus, the present invention is useful for applications such as gene therapy, large scale production of proteins and antibodies, cell-based screening assays, functional genomics, proteomics, metabolomics, and regulation of traits in transgenic organisms, where control of gene expression levels is desirable. An advantage of the present invention is that it provides a means to regulate gene expression and to tailor expression levels to suit the user's requirements.

Provided is a compound having the structure:
(SIG)-(SI-MOD).sub.m
where SIG is a signaling molecule, SI is a self-immolative structure bound to SIG such that SIG has a reduced signal relative to the signal of SIG without SI, MOD is a moiety bound to SI that is subject to modification by an activator, and m is an integer from 1 to about 10. When MOD is modified by an activator, SI is destabilized and self-cleaved from SIG such that SIG generates an increased signal. Also provided are methods of determining whether a sample, such as a cell, comprises an activator, such as a nitroreducase, using the compound. Further provided are methods of determining whether a mammalian cell is hypoxic using the compound where nitroreductase is the activator. A method of detecting a microorganism that comprises a nitroreductase using the compound where nitroreductase is the activator is also provided.

The present invention provides diacylhydrazine ligands and chiral diacylhydrazine ligands for use with ecdysone receptor-based inducible gene expression systems. Thus, the present invention is useful for applications such as gene therapy, large scale production of proteins and antibodies, cell-based screening assays, functional genomics, proteomics, metabolomics, and regulation of traits in transgenic organisms, where control of gene expression levels is desirable. An advantage of the present invention is that it provides a means to regulate gene expression and to tailor expression levels to suit the user's requirements.

The present invention provides diacylhydrazine ligands and chiral diacylhydrazine ligands for use with ecdysone receptor-based inducible gene expression systems. Thus, the present invention is useful for applications such as gene therapy, large scale production of proteins and antibodies, cell-based screening assays, functional genomics, proteomics, metabolomics, and regulation of traits in transgenic organisms, where control of gene expression levels is desirable. An advantage of the present invention is that it provides a means to regulate gene expression and to tailor expression levels to suit the user's requirements.