Macroporous polymer-graphene oxide (GO) composites were successfully prepared using Pickering high internal phase emulsion (HIPE) templates. GO flakes were modified by the cationic surfactant cetyltrimethylammonium bromide (CTAB) and used as the stabilizer of water-in-oil (W/O) Pickering emulsions. CTAB-modified GO is effective at stabilizing W/O Pickering HIPEs, and the lowest GO content is only about 0.2 mg mL(-1) (relative to the volume of the oil phase). The close-cell morphology of the resulting poly-Pickering HIPEs is observed, and the void size of the porous polymers is tuned by varying the concentration of GO. Three-dimensional macroporous chemically modified graphene (CMG) monoliths with a high specific surface area of about 490 m(2) g(-1) were obtained after removing the cellular polymer substrates through calcination. The micropores were also found in CMGs, which may be caused by the decomposition of CTAB adsorbed on the surface of GO.
Interconnected macroporous polymers were prepared by copolymerizing methyl acrylate (MA) via Pickering high internal phase emulsion (HIPE) templates with modified silica particles. The pore structure of the obtained polymer foams was observed by field-emission scanning electron microscopy (FE-SEM). Gas permeability was characterized to evaluate the interconnectivity of macroporous polymers. The polymerization shrinkage of continuous phase tends to form open pores while the solid particles surrounding the droplets act as barriers to produce closed pores. These two conflicting factors are crucial in determining the interconnectivity of macroporous polymers. Thus, poly-Pickering HIPEs with high permeability and well-defined pore structure can be achieved by tuning the MA content, the internal phase fraction, and the content of modified silica particles.
n-Octadecyltrimethoxysilane (ODS)-modified silica particles were used as sole Pickering stabilizer to prepare water-in-oil Pickering high internal phase emulsions (HIPEs) with an internal phase volume of 80%. After polymerization of the continuous phase of HIPEs, interconnected macroporous polymers were obtained when modified silica was initially dispersed in water to form a micelle-like structure. However, silica particles in oil phase resulted in closed-cell pores. The pore size, the pore wall morphology, and the interconnectivity of polymer foams could be adjusted finely by the grafted amounts of ODS, modified silica concentrations, and the initial location of Pickering stabilizer. The gas permeation of interconnected porous polymers increased dramatically with the increase of the hydrophobicity of silica particles from 3 to 153 mL/min.
Biotinidase (BTD) deficiency (OMIM 253260) is an autosomal recessively inherited metabolic disorder resulting from deficient activity of the BTD enzyme, which can cleave and release biotin from a variety of biotin-dependent carboxylases, and is therefore recognized as a tool to recycle biotin. Being a condition caused by variations on BTD gene with a consequence of free biotin shortage, BTD deficiency may impair the activity of biotin-dependent carboxylases, and thus bring about a buildup of potentially toxic compounds in the body, primarily 3-hydroxyisovaleryl-carnitine in plasma as well as 3-hydroxyisovaleric acid in urine. The phenotype of BTD deficiency may vary dramatically, from asymptomatic adults to severe neurological anomalies, even death in infancy. In the present study, we reported on a 5-month-old boy, whose parents sought for medical consultation in our clinic for their son due to his loss of consciousness, repeated tetany, and motor retardation. Detailed clinical features included severe psychomotor retardation, hypotonia, as well as failure to thrive. The brain MRI at 12 months showed cerebellar hypoplasia and multiple foci of leukodystrophy. The result of antiepileptic therapy was not satisfying. During hospitalization, BTD deficiency was suggested by elevated concentration of 3-hydroxyisovaleryl-carnitine in the blood spots and 3-hydroxyisovaleric acid in the urine. The child was then diagnosed with profound BTD deficiency based on the above findings and low BTD enzyme activity. Subsequent mutational analysis revealed a novel homozygous variant, c.637_637delC (p.H213Tfs*51) in exon 4 of BTD gene in the proband, which was recognized as a further support to the diagnosis. Therefore, biotin treatment was started immediately, eventually with satisfactory outcomes achieved in terms of prevention of epileptic seizure, performance in deep tendon reflexes, and improvement of muscular hypotonia, but unfortunately, the therapy failed to show any evident effects on poor feeding and intellectual disability. This painful lesson suggests that newborn screening for inherited metabolic diseases is essential for early identification and treatment, which should have been performed in this case to avoid this tragedy.
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