Applications of aptamers as sensors.

Aptamers are ligand-binding nucleic acids whose affinities and selectivities can rival those of antibodies. They have been adapted to analytical applications not only as alternatives to antibodies, but as unique reagents in their own right. In particular, aptamers can be readily site-specifically modified during chemical or enzymatic synthesis to incorporate particular reporters, linkers, or other moieties.

Neuroactive conducting scaffolds: nerve growth factor conjugation on active ester-functionalized polypyrrole.

Electrically conductive and biologically active scaffolds are desirable for enhancing adhesion, proliferation and differentiation of a number of cell types such as neurons. Hence, the incorporation of neuroactive molecules into electroconductive polymers via a specific and stable method is essential for neuronal tissue engineering applications. Traditional conjugation approaches dramatically impair conductivities and/or stabilities of the scaffolds and ligands.

Carboxy-endcapped conductive polypyrrole: biomimetic conducting polymer for cell scaffolds and electrodes.

Numerous regenerating tissues respond favorably to electrical stimulation, creating a need for a bioactive conducting platform for tissue engineering applications. The drive for biosensors and electrode coatings further requires control of the surface properties of promising conductive materials such as polypyrrole. Here we present carboxy-endcapped polypyrrole (PPy-alpha-COOH), a unique bioactive conducting polymer with a carboxylic acid layer, composed of a polypyrrole (PPy) surface modified with pyrrole-alpha-carboxylic acid (Py-alpha-COOH).

Carboxylic acid-functionalized conductive polypyrrole as a bioactive platform for cell adhesion.

Electroactive polymers such as polypyrrole (PPy) are highly attractive for a number of biomedical applications, including their use as coatings for electrodes or neural probes and as scaffolds to induce tissue regeneration. Surface modification of these materials with biological moieties is desired to enhance the biomaterial-tissue interface and to promote desired tissue responses. Here, we present the synthesis and physicochemical characterization of poly(1-(2-carboxyethyl)pyrrole) (PPyCOOH), a PPy derivative that contains a chemical group that can be easily modified with biological moieties at the N-position of the polymer backbone.

Simultaneous time-of-flight secondary ion MS quantitative analysis of drug surface concentration and polymer degradation kinetics in biodegradable poly(L-lactic acid) blends.

This paper reports a new quantitative method of analyzing both the earliest stage of degradation of a polymer and the surface concentration of an additive using time-of-flight secondary ion mass spectrometry (TOF-SIMS). The static SIMS spectra of triphenylamine (Ph3N)/poly(L-lactic acid) (PLLA) (20:80 wt %) blend matrixes hydrolyzed in buffered conditions within a short-term (<48 h) period are simultaneously analyzed in the low-mass range for the surface accumulation profile of Ph3N and in the high-mass range to determine the hydrolytic degradation kinetics of PLLA, respectively. The results provide new insight in evaluating the surface concentration of Ph3N (pKb approximately 0) from the blends to see how it relates to the reactions (hydrolytic PLLA degradation) occurring in the surface region in the initial induction period over which negligible loss of polymer weight is observed.

Analysis of the initial burst of drug release coupled with polymer surface degradation.

Purpose: Local pH effect on the release of a model pH-inert hydrophobic drug coupled with polymer degradation is described at the induction phase of biodegradable polymer erosion for better understanding the nature of initial burst of a drug.

Methods: Using a novel approach with time-of-flight secondary ion mass spectrometry. both surface concentration of Ph3N and degradation kinetics of PLLA are simultaneously and independently determined from a model Ph3N/PLLA (20:80 wt%) blend matrix (t approximately 0.

Quantitative TOF-SIMS analysis of oligomeric degradation products at the surface of biodegradable poly(alpha-hydroxy acid)s.

This paper reports the development of a new method for quantification of the hydrolytic surface degradation kinetics of biodegradable poly(alpha-hydroxy acid)s using time-of-flight secondary ion mass spectrometry (TOF-SIMS). We report results from static SIMS spectra of a series of poly(alpha-hydroxy acid)s including poly(glycolic acid), poly(L-lactic acid), and random poly(D,L-lactic acid-co-glycolic acid) hydrolyzed in various buffer systems. The distribution of the most intense peak intensities of ions generated in high mass range of the spectrum reflects the intact degradation products (oligomeric hydrolysis products) of each biodegradable polymer.

Surface perspectives in the biomedical applications of poly(alpha-hydroxy acid)s and their associated copolymers.

Impressive advances in biotechnology, bioengineering, and biomaterials with unique properties have led to increased interest in polymers and other novel materials in biological and biomedical research and development over the past two decades. Although biomaterials have already made an enormous impact in biomedical research and clinical practice, there is a need for better understanding of the surface and interfacial chemistry between tissue (or cells) and biomedical materials. This is because the detailed physicochemical events related to the biological response to the surface of materials still often remain obscure, even though surface properties are important determinants of biomedical material function.