The effect of copolymerization and carbon nanoelements on the performance of poly(2,5-di(thienyl)pyrrole) biosensors

The development of biosensing interfaces based on copolymerization of benzenamine-2,5-di(thienyl)pyrrole (SNS-An) with 3,4-ethylenedioxythiophene (EDOT) is reported. Both homopolymer P(SNS-An) and copolymer P(SNS-An-co-EDOT) films were prepared and evaluated, in terms of biosensing efficiency, upon incorporation of carbon nanoelements (carbon nanotubes and fullerene) and cross-linking of glucose oxidase. The copolymer revealed superior performance as a biosensing interface as compared to the homopolymer structure or previously reported P(SNS) biosensors. The analytical characteristics and stability studies were performed both at cathodic potential, monitoring O₂ consumption, as a result of catalytic reaction of glucose oxidase towards glucose and at anodic potential, following the oxidation of the H₂O₂ produced during the catalytic reaction. Whilst the measurements on the positive side offered an extended linear range (0.01-5.0 mM), the negative side provided sensitivity up to 104.96 μA/mMcm^-1 within a shorter range. Detection limits were as low as 1.9 μM with Km value of 0.49 mM. Lastly, the most performant biosensing platforms, including copolymeric structure and CNTs were employed for analysis in real samples.

Polymerization and biosensor application of water soluble peptide-SNS type monomer conjugates

A simple and efficient approach for the preparation of a biosensing platform was developed based on newly designed peptide-SNS type monomer conjugates. The approach involves the electrochemical polymerization of the peptide-SNS type monomer on the electrode surface. To synthesize the peptide bearing monomers, the SNS-type monomer having a carboxylic acid functional group was anchored to the C-terminal of the peptide by solid phase peptide synthesis via coupling reagents. Utilization of peptides to increase the solubility of the monomers was first investigated in this report. The obtained monomers, soluble in water, were fully characterized by spectral analyses and utilized as matrices for biomolecule attachment. Polymerization of monomers in water has the potential to provide an alternative process for the electrochemical preparation of the polymers in aqueous media, without using any organic solvent. Under the optimized conditions, the biosensor responded to the target analyte, glucose, in a strikingly selective and sensitive manner, and showed promising feasibility for the quantitative analysis of glucose in beverages.

Bioconjugation and Applications of Amino Functional Fluorescence Polymers

Synthesis and novel applications of biofunctional polymers for diagnosis and therapy are promising area involving various research domains. Herein, three fluorescent polymers, poly(p-phenylene-co-thiophene), poly(p-phenylene), and polythiophene with amino groups (PPT-NH₂ , PPP-NH₂ , and PT-NH₂ , respectively) are synthesized and investigated for cancer cell targeted imaging, drug delivery, and radiotherapy. Polymers are conjugated to anti-HER2 antibody for targeted imaging studies in nontoxic concentrations. Three cell lines (A549, Vero, and HeLa) with different expression levels of HER2 are used. In a model of HER2 expressing cell line (A549), radiotherapy experiments are carried out and results show that all three polymers increase the efficacy of radiotherapy. This effect is even more increased when conjugated to anti-HER2. In the second part of this work, one of the selected polymers (PT-NH₂ ) is conjugated with a drug model; methotrexate via pH responsive hydrazone linkage and a drug carrier property of PT-NH₂ is demonstrated on neuroblastoma (SH-SY5Y) cell model. Our results indicate that, PPT-NH₂ , PPP-NH₂ , and PT-NH₂ have a great potential as biomaterials for various bioapplications in cancer research.

Enhancing biosensor properties of conducting polymers via copolymerization: Synthesis of EDOT-substituted bis(2-pyridylimino)isoindolato-palladium complex and electrochemical sensing of glucose by its copolymerized film

1,3-Bis(2-pyridylimino)isoindoline derivative bearing 3,4-ethylenedioxythiophene (EDOT-BPI) and its palladium complex (EDOT-PdBPI) were synthesized and characterized by FT-IR, ¹H NMR, ¹³C NMR, UV-Vis spectroscopies and via mass spectrometric analysis. Polymerization of EDOT-PdBPI and copolymerization with 4-amino-N-(2,5-di(thiophene-2-yl)-1H-pyrrol-1-yl)benzamide (HKCN) were carried out by an electrochemical method. In addition, P(EDOT-PdBPI-co-HKCN) modified graphite rod electrode was improved for amperometric glucose sensor based on glucose oxidase (GOx). In this novel biosensor matrix, amino groups in HKCN were used for the enzyme immobilization. On the other hand, EDOT-PdBPI used to mediate the bioelectrocatalytic reaction. Amperometric detection was carried out following oxygen consumption at -0.7V vs. the Ag reference electrode in phosphate buffer (50mM, pH 6.0). The novel biosensor showed a linear amperometric response for glucose within a concentration range of 0.25mM to 2.5mM (LOD: 0.176mM). Amperometric signals at 1mM of glucose were 17.9μA under anaerobic conditions. Amperometric response of the P(EDOT-PdBPI-co-HKCN)/GOx electrode decreased only by 13% within eight weeks. The P(EDOT-PdBPI-co-HKCN)/GOx electrode showed good selectivity in the presence of ethanol and phenol. This result shows that, modification of the proposed biosensor by copolymerization of amine functionalized monomer, which is indispensable to the enzyme immobilization, with palladium complex bearing monomer, which is mediate the bioelectrocatalytic reaction, have provided to give perfect response to different glucose concentrations.

Comparative cell adhesion properties of cysteine extended peptide architectures

This study presents the comparative cell attachment investigation of TAT and well-known RGD peptide modified surfaces.

Application of PAMAM dendrimers in optical sensing

In this review, recent advances have been reported in those PAMAM dendrimer-based optical sensors that are used for the detection of pH, cations, and other analyte.

Bioactive surface design based on functional composite electrospun nanofibers for biomolecule immobilization and biosensor applications

The combination of nanomaterials and conducting polymers attracted remarkable attention for development of new immobilization matrices for enzymes. Hereby, an efficient surface design was investigated by modifying the graphite rod electrode surfaces with one-step electrospun nylon 6,6 nanofibers or 4% (w/w) multiwalled carbon nanotubes (MWCNTs) incorporating nylon 6,6 nanofibers (nylon 6,6/4MWCNT). High-resolution transmission electron microscopy study confirmed the successful incorporation of the MWCNTs into the nanofiber matrix for nylon 6,6/4MWCNT sample. Then, these nanofibrous surfaces were coated with a conducting polymer, (poly-4-(4,7-di(thiophen-2-yl)-1H-benzo[d]imidazol-2-yl)benzaldehyde) (PBIBA) to obtain a high electroactive surface area as new functional immobilization matrices. Due to the free aldehyde groups of the polymeric structures, a model enzyme, glucose oxidase was efficiently immobilized to the modified surfaces via covalent binding. Scanning electron microscope images confirmed that the nanofibrous structures were protected after the electrodeposition step of PBIBA and a high amount of protein attachment was successfully achieved by the help of high surface to volume ratio of electroactive nanofiber matrices. The biosensors were characterized in terms of their operational and storage stabilities and kinetic parameters (K(m)(app) and Imax). The resulting novel glucose biosensors revealed good stability and promising Imax values (10.03 and 16.67 μA for nylon 6,6/PBIBA and nylon 6,6/4MWCNT/PBIBA modified biosensors, respectively) and long shelf life (32 and 44 days for nylon 6,6/PBIBA and nylon 6,6/4MWCNT/PBIBA modified biosensors, respectively). Finally, the biosensor was tested on beverages for glucose detection.

Peptide-modified conducting polymer as a biofunctional surface: monitoring of cell adhesion and proliferation

A designed bio-functional surface is a promising candidate forcell-culture-on-a-chipapplications.