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1.
Biosens Bioelectron ; 207: 114204, 2022 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-35366578

RESUMO

Medical diagnostic sector is relying on affordable, handheld devices integrating smart biosensing and transducing interfaces that enable clinical analysis with minimal end-user intervention and resource requirements. In response, we propose here, a SIM card-type pH responsive polymer-modified paper-based biosensing device, coupled to a smartphone, for the determination of urinary creatinine. A vertical microfluidic channel was fabricated on a paper strip by wax printing. The hydrophilic area was coated by a poly(methylmethacrylate)/poly(methacrylic acid) random copolymer, PMMA-co-PMAA, and on top of it, creatinine deiminase (CD) was immobilized. Data demonstrated, on the one hand, zero vertical flow of urine through the enzyme-free PMMA-co-PMAA-modified paper strip, i.e., a high selectivity against the components of the matrix, and on the other hand, in the presence of CD, a creatinine -concentration dependent commence of sample's downward flow due to the selective, creatinine-triggered degradation of the copolymer by the enzymatically produced ammonia. This CD/PMMA-co-PMAA paper-based biosensing smart assembly is coupled with three conductive strips, which enable the automatic on/off (sample addition/measurement end) measurement of the copolymer degradation time, through electric resistance measurements. It also features an in-built sample well and wireless communication support through the integration of a Bluetooth® microprocessor incorporated with time and resistance measuring circuits. Using newly synthesized pH responsive PMMA-co-PMAA at different molecular weights and volume fraction ratios offering tunable dissolution properties, the detection range was adjusted over 3-30 mM creatinine to overspread the normal range of creatinine in urine. The device was successfully applied to the determination of urinary creatinine.


Assuntos
Técnicas Biossensoriais , Smartphone , Creatinina/urina , Polimetil Metacrilato/química , Urinálise
2.
Polymers (Basel) ; 13(23)2021 Nov 28.
Artigo em Inglês | MEDLINE | ID: mdl-34883671

RESUMO

An approach to obtaining various nanostructures utilizing a well-studied polystyrene-b-poly(isoprene) or PS-b-PI diblock copolymer system through chemical modification reactions is reported. The complete hydrogenation and partial sulfonation to the susceptible carbon double bonds of the PI segment led to the preparation of [polystyrene-b-poly(ethylene-alt-propylene)] as well as [polystyrene-b-poly(sulfonated isoprene-co-isoprene)], respectively. The hydrogenation of the polyisoprene block results in enhanced segmental immiscibility, whereas the relative sulfonation induces an amphiphilic character in the final modified material. The successful synthesis of the pristine diblock copolymer through anionic polymerization and the relative chemical modification reactions were verified using several molecular and structural characterization techniques. The thin film structure-properties relationship was investigated using atomic force microscopy under various conditions such as different solvents and annealing temperatures. Small-angle X-ray scattering was employed to identify the different observed nanostructures and their evolution upon thermal annealing.

3.
Polymers (Basel) ; 13(21)2021 Nov 04.
Artigo em Inglês | MEDLINE | ID: mdl-34771373

RESUMO

Novel hybrid materials of the PB-b-P(o-Bn-L-Tyr) and PI-b-P(o-Bn-L-Tyr) type (where PB: 1,4/1,2-poly(butadiene), PI: 3,4/1,2/1,4-poly(isoprene) and P(o-Bn-L-Tyr): poly(ortho-benzyl-L-tyrosine)) were synthesized through anionic and ring-opening polymerization under high-vacuum techniques. All final materials were molecularly characterized through infrared spectroscopy (IR) and proton and carbon nuclear magnetic resonance (1H-NMR, 13C-NMR) in order to confirm the successful synthesis and the polydiene microstructure content. The stereochemical behavior of secondary structures (α-helices and ß-sheets) of the polypeptide segments combined with the different polydiene microstructures was also studied. The influence of the α-helices and ß-sheets, as well as the polydiene chain conformations on the thermal properties (glass transition temperatures, thermal stability, α- and ß-relaxation) of the present biobased hybrid copolymers, was investigated through differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and dielectric spectroscopy (DS). The obtained morphologies in thin films for all the synthesized materials via atomic force microscopy (AFM) indicated the formation of polypeptide fibrils in the polydiene matrix.

4.
Polymers (Basel) ; 13(14)2021 Jul 14.
Artigo em Inglês | MEDLINE | ID: mdl-34301065

RESUMO

A novel approach to obtaining nanocomposite materials using anionic sequential polymerization and post-synthetic esterification reactions with chemically modified graphene sheets (CMGs) is reported. The anionically synthesized diblock copolymer precursors of the PS-b-PI-OH type were grafted to the chemically modified -COOH groups of the CMGs, giving rise to the final composite materials, namely polystyrene-b-poly(isoprene)-g-CMGs, which exhibited enhanced physicochemical properties. The successful synthesis was determined through multiple molecular characterization techniques together with thermogravimetric analysis for the verification of increased thermal stability, and the structure/properties relationship was justified through transmission electron microscopy. Furthermore, the arrangement of CMGs utilizing lamellar and cylindrical morphologies was studied in order to determine the effect of the loaded CMGs in the adopted topologies.

5.
Molecules ; 25(24)2020 Dec 19.
Artigo em Inglês | MEDLINE | ID: mdl-33352785

RESUMO

To the best of our knowledge, this is the very first time that a thorough study of the synthetic procedures, molecular and thermal characterization, followed by structure/properties relationship for symmetric and non-symmetric second generation (2-G) dendritic terpolymers is reported. Actually, the synthesis of the non-symmetric materials is reported for the first time in the literature. Anionic polymerization enables the synthesis of well-defined polymers that, despite the architecture complexity, absolute control over the average molecular weight, as well as block composition, is achieved. The dendritic type macromolecular architecture affects the microphase separation, because different morphologies are obtained, which do not exhibit long range order, and various defects or dislocations are evident attributed to the increased number of junction points of the final material despite the satisfactory thermal annealing at temperatures above the highest glass transition temperature of all blocks. For comparison reasons, the initial dendrons (miktoarm star terpolymer precursors) which are connected to each other in order to synthesize the final dendritic terpolymers are characterized in solution and in bulk and their self-assembly is also studied. A major conclusion is that specific structures are adopted which depend on the type of the core connection between the ligand and the active sites of the dendrons.


Assuntos
Dendrímeros/química , Polímeros/química , Polimerização , Temperatura
6.
Molecules ; 25(23)2020 Nov 25.
Artigo em Inglês | MEDLINE | ID: mdl-33255708

RESUMO

The synthesis of two (2) novel triblock terpolymers of the ABC type and one (1) of the BAC type, where A, B and C are chemically different segments, such as polystyrene (PS), poly(butadiene) (PB1,4) and poly(dimethylsiloxane) (PDMS), is reported; moreover, their corresponding molecular and bulk characterizations were performed. Very low dimensions are evident from the characterization in bulk from transmission electron microscopy studies, verified by small-angle X-ray data, since sub-16 nm domains are evident in all three cases. The self-assembly results justify the assumptions that the high Flory-Huggins parameter, χ, even in low molecular weights, leads to significantly well-ordered structures, despite the complexity of the systems studied. Furthermore, it is the first time that a structure/properties relationship was studied for such systems in bulk, potentially leading to prominent applications in nanotechnology and nanopatterning, for as low as sub-10 nm thin-film manipulations.


Assuntos
Peso Molecular , Polimerização , Polímeros/química , Ânions/química , Microscopia Eletrônica de Transmissão , Análise Espectral , Temperatura
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