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Although there are many studies on CO2 adsorption via PEI‐modified carbon particles, metal–organic frameworks, zeolitic imidazolate frameworks, and silica‐based porous structures, only a limited number of studies on solely cross‐linked PEI‐based structures. Here, the CO2 adsorption capacities of PEI‐based microgels and cryogels were investigated. The effects of various parameters influencing the CO2 adsorption capacity of PEI‐based structures, for example, crosslinker types, PEI types (branched [bPEI] or linear [lPEI]), adsorbent types (microgel or cryogel), chemical‐modification including their complexes were examined. NaOH‐treated glycerol diglycidyl ether (GDE) crosslinked lPEI microgels exhibited higher CO2 adsorption capacity among other microgels with 0.094 ± 0.006 mmol CO2/g at 900 mm Hg, 25°C with 2‐ and 7.5‐fold increase upon pentaethylenehexamine (PEHA) modification and Ba(II) metal ion complexing, respectively. The CO2 adsorption capacity of bPEI and lPEI‐based cryogels were compared and found that lPEI‐GDE cryogels had higher adsorption capacity than bPEI‐GDE cryogels with 0.188 ± 0.01 mmol CO2/g at 900 mm Hg and 25°C. The reuse studies revealed that NaOH‐treated GDE crosslinked bPEI and lPEI microgels and cryogels showed promising potential, for example, after 10‐times repeated use >50% CO2 adsorption capacity was retained. The results affirmed that PEI‐based microgels and cryogels are encouraging materials for CO2 capture and reuse applications. [ABSTRACT FROM AUTHOR]

Here, the use of cellulose films (CFs) produced from low‐quality cotton is reported as a template for in situ synthesis of well‐known conductive polymers, e.g., polyaniline (PANI) and polypyrrole (PPY) via oxidative polymerization. Three successive monomer loading/polymerization cycles of aniline (ANI) and pyrrole (PY) within CFs as PANI@CF or PPY@CF are carried out to increase the amount of conductive polymer content. The contact angle (CA) for three times ANI and PPY loaded and polymerized CFs as 3PANI@CF and 3PPY@CF are determined as 26.3±2.8 and 42.3±0.6 degrees, respectively. As the electrical conductivity is increased with increased number of conductive polymer synthesis within CF, the higher conductivity values, 3×10−4±8.1×10−5 S.cm−1 and 2.1×10−3±5.8×10−4 S.cm−1, respectively are measured for 3PANI@CF and 3PPY@CF composites. It is found that PANI@CF composites are hemolytic, whereas PPY@CF composites are not at 1 mg mL−1 concentrations. All PPY@CF composites exhibit better biocompatibility than PANI@CF composites on L929 fibroblast cells with more than 70±8% viability at 1 mg of CF‐based conductive polymer composites. Moreover, MIC and MBC values of 3PPY@CF composites for Escherichia coli (ATCC8739) and Staphylococcus aureus (ATCC6538) are determined as 2.5 and 5.0 mg.mL−1, whereas these values are estimated as 5 and 10 mg.mL−1 for Candida albicans (ATCC10231). [ABSTRACT FROM AUTHOR]

Graphitic carbon nitride (g-C3N4) is an intriguing nanomaterial that exhibits photoconductive fluorescence properties under UV–visible light. Dopamine (DA) coating of g-C3N4 prepared from melamine was accomplished via self-polymerization of DA as polydopamine (PDA). The g-C3N4 was coated with PDA 1, 3, and 5 times repeatedly as (PDA@g-C3N4) in tris buffer at pH 8.5. As the number of PDA coatings was increased on g-C3N4, the peak intensity at 1512 cm−1 for N–H bending increased. In addition, the increased weight loss values of PDA@g-C3N4 structures at 600 °C from TGA thermograms confirmed that the coating was accomplished. The band gap of g-C3N4, 2.72 eV, was reduced to 0.87 eV after five coatings with PDA. A pristine g-C3N4 was found to have an isoelectric point (IEP) of 4.0, whereas the isoelectric points of 1PDA@g-C3N4 and 3PDA@g-C3N4 are close to each other at 3.94 and 3.91, respectively. On the other hand, the IEP of 5PDA@g-C3N4 was determined at pH 5.75 assuming complete coating with g-C3N4. The biocompatibility of g-C3N4 and PDA@g-C3N4 against L929 fibroblast cell lines revealed that all PDA@g-C3N4 coatings were found to be biocompatible up to a 1000 mg/mL concentration, establishing that PDA coatings did not adversely affect the biocompatibility of the composite materials. In addition, PDA@g-C3N4 was screened for antioxidant potential via total phenol content (TPC) and total flavonoid content assays and it was found that PDA@g-C3N4 has recognizable TPC values and increased linearly with an increased number of PDA coatings. Furthermore, blood compatibility of pristine g-C3N4 is enhanced considerably upon PDA coating, affirmed by hemolysis and the blood clotting index%. Additionally, α-glucosidase inhibitory properties of PDA@g-C3N4 structures revealed that 67.6 + 9.8% of this enzyme was evenly inhibited by 3PDA@g-C3N4 structure. [ABSTRACT FROM AUTHOR]

Fluorescent graphitic carbon nitride (g-C3N4) doped with various heteroatoms, such as B, P, and S, named Bg-C3N4, Pg-C3N4, and Sg-C3N4, were synthesized with variable band-gap values as diagnostic materials. Furthermore, they were embedded within hyaluronic acid (HA) microgels as g-C3N4@HA microgel composites. The g-C3N4@HA microgels had a 0.5–20 μm size range that is suitable for intravenous administration. Bare g-C3N4 showed excellent fluorescence ability with 360 nm excitation wavelength and 410–460 emission wavelengths for possible cell imaging application of g-C3N4@HA microgel composites as diagnostic agents. The g-C3N4@HA-based microgels were non-hemolytic, and no clotting effects on blood cells or cell toxicity on fibroblasts were observed at 1000 μg/mL concentration. In addition, approximately 70% cell viability for SKMEL-30 melanoma cells was seen with Sg-C3N4 and its HA microgel composites. The prepared g-C3N4@HA and Sg-C3N4@HA microgels were used in cell imaging because of their excellent penetration capability for healthy fibroblasts. Furthermore, g-C3N4-based materials did not interact with malignant cells, but their HA microgel composites had significant penetration capability linked to the binding function of HA with the cancerous cells. Flow cytometry analysis revealed that g-C3N4 and g-C3N4@HA microgel composites did not interfere with the viability of healthy fibroblast cells and provided fluorescence imaging without any staining while significantly decreasing the viability of cancerous cells. Overall, heteroatom-doped g-C3N4@HA microgel composites, especially Sg-C3N4@HA microgels, can be safely used as multifunctional theragnostic agents for both diagnostic as well as target and treatment purposes in cancer therapy because of their fluorescent nature. [ABSTRACT FROM AUTHOR]

The synthesis of two-dimensional (2D) graphitic g -C3N4 and heteroatom-doped graphitic H@ g -C3N4 (H: B, P, or S) particles were successfully done using melamine as source compounds and boric acid, phosphorous red, and sulfur as doping agents. The band gap values of 2D g -C3N4, B50@ g -C3N4, P50@ g -C3N4, and S50@ g -C3N4 structures were determined as 2.90, 3.03, 2.89, and 2.93 eV, respectively. The fluorescent emission wavelengths of 2D g -C3N4, B50@ g -C3N4, P50@ g -C3N4, and S50@ g -C3N4 structures were observed at 442, 430, 441, and 442 nm, respectively upon excitation at λ Ex = 325 nm. There is also one additional new emission wavelength was found at 345 nm for B50@ g -C3N4 structure. The blood compatibility test results of g -C3N4, B50@ g -C3N4, P50@ g -C3N4, and S50@ g -C3N4 structures revealed that all materials are blood compatible with <2% hemolysis and >90% blood clotting indices at 100 μ g ml−1 concentration. The cell toxicity of the prepared 2D graphitic structures were also tested on L929 fibroblast cells, and even the heteroatom doped has g -C3N4 structures induce no cytotoxicity was observed with >91% cell viability even at 250 μ g ml−1 particle concentration with the exception of P50@g-C3N4 which as >75 viability. Moreover, for 2D g -C3N4, B50@ g -C3N4, and S50@ g -C3N4 constructs, even at 500 μ g ml−1 concentration, >90% cell viabilities was monitored. As a diagnostic material, B50@ g -C3N4 was found to have significantly high penetration and distribution abilities into L929 fibroblast cells granting a great potential in fluorescence imaging and bioimaging applications. Furthermore, the elemental doping with B, P, and S of g -C3N4 were found to significantly increase the photodynamic antibacterial activity e.g. more than half of bacterial elimination by heteroatom-doped forms of g -C3N4 under UVA treatment was achieved. [ABSTRACT FROM AUTHOR]