Thermosensitive Metal Chelation Dual-Template Epitope Imprinting Polymer Using Distillation-Precipitation Polymerization for Simultaneous Recognition of Human Serum Albumin and Transferrin

A new type of thermosensitive dual-template epitope molecular imprinting polymer was prepared and coated on magnetic carbon nanotubes (MCNTs@D-EMIP) for simultaneous recognition of human serum albumin (HSA) and transferrin (Trf) via the strategies of dual-template epitope imprinting, metal chelation imprinting, and distillation-precipitation polymerization (DPP). C-terminal peptides of HSA and C-terminal peptides of Trf were selected as templates, zinc acrylate and N-isopropylacrylamide were used as functional monomers, and MCNTs@D-EMIP was prepared by the method of DPP. The two types of template epitopes were immobilized by metal chelation and six-membered ring formed with zinc acylate. MCNTs@D-EMIP was prepared in only 30 min, which was much shorter than other polymerization methods. The resultant MCNTs@D-EMIP showed excellent specific recognition ability toward HSA and Trf. The adsorption amounts of MCNTs@D-EMIP for HSA and Trf were 103.67 and 68.48 mg g^-1 and the imprinting factors were 2.57 and 2.17, respectively. In addition, MCNTs@D-EMIP displayed a thermosensitive property to realize temperature-controlled recognition and release of target proteins. Furthermore, the results of high-performance liquid chromatography analysis proved that MCNTs@D-EMIP could be applied to specifically recognize two types of targets simultaneously in the biosample. The proposed strategy provided a preparation method for the thermosensitive dual-template epitope imprinting polymer via dual-template imprinting, metal chelation imprinting, and DPP.

Silicon nanoparticles coated with an epitope-imprinted polymer for fluorometric determination of cytochrome c

The authors describe a composite consisting of silicon nanoparticles that were first coated with SiO₂ and then with a molecularly imprinted polymer (SiNP@SiO₂@MIP). The MIP was generated by dual epitope imprinting such that it can recognize cytochrome c (Cyt c). The MIP on the NPs was prepared from the functional monomer zinc(II) acrylate (ZnA), the crosslinker ethylene glycol dimethacrylate and the initiator 2,2'-azoisobutyronitrile. Dual epitope templates for Cyt c included (a) a C-terminal nonapeptide (AYLKKATNE), and (b) an N-terminal nonapeptide (GDVEKGKKI). The chelation between Zn(II) of ZnA and the amino groups or hydroxy groups of the template nonapeptides warrants good recognition and capture of Cyt c. The fluorescence originating from SiNPs has excitation/emission peaks at 360/480 nm and is quenched by Cyt c in the 0.50-40.0 μM concentration range. The correlation coefficient for the calibration plot of the imprinted NPs is 0.9937. The detection limit is 0.32 ± 0.01 μM, the precisions of six replicate detections at levels of 0.5, 20 and 40 μM Cyt c are 3.2, 2.7 and 2.8%, respectively, and the imprinting factor is 2.43. Compared to single epitope template imprinting, dual epitope imprinting results in improved selectivity. The imprinted nanoparticles can discriminate Cyt c even if one amino acid is mismatched. The method was applied to the determination of Cyt c in spiked diluted human serum and gave recoveries between 94.0 and 107.5%. Graphical Abstract A fluorescent material of the architecture silicon nanoparticle@SiO₂@molecularly imprinted polymer (SiNP@SiO₂@MIP) was fabricated by dual epitope imprinting and a metal-chelating method. The chelation between Zn(II) of the functional monomer zinc(II) acrylate and the amino groups or hydroxy groups of template warrants that the material recognizes and captures cytochrome c well, and this results in fluorescence quenching.

[Two cases with generalized intracranial calcification due to hereditary folate malabsorption and literature review]

Objective: This study aimed to investigate the clinical, biochemical and genetic features of two Chinese children with hereditary folate malabsorption. Method: Clinical features, laboratory examinations, treatment and SLC46A1 gene of two cases were studied. Reports on hereditary folate malabsorption utill September of 2016 were searched and the clinical and genetic characteristics of reported cases were summarized. Result: The two patients presented with megaloblastic anemia from their infant period and seizures, psychomotor retardation and regression. In case1, mean corpuscular volume (MCV) was 100 fl. Serum folate was 9.96 nmol/L. Folate and 5-methylenetetrahydrofolate in cerebrospinal fluid were 0 and 0.01 separately. In case 2, MCV was 93.9 fl. Serum folate was 4.49 nmol/L. The concentration of folate and 5-methylenetetrahydrofolate in cerebrospinal fluid were both zero. On their brain CT, progressive bilateral symmetrical calcification was observed. On their SLC46A1 gene, four mutations were identified. Case 1 had one novel mutation, c. 1238T>C (L413P) and c. 194-195insG (p.Cys66LeufsX99). From Case 2, two reported mutations, c. 1A>T (M1L) and c. 194-195insG (p.Cys66LeufsX99) were identified. The administration of folinic acid (60 to 120 mg per day) was initiated after diagnosis. Clinical improvement and normalized hematologic markers were observed after treatment. Totally 37 cases were reported in reviewed English literature, including 30 cases with mutations on SLC46A1 gene (only one Chinese patient). All the cases had the onset in infancy. The ratio of boys to girls was 1 to 1.5. Main manifestations were characterized by megaloblastic anemia (77%), failure to thrive (50%), diarrhea (27%), psychomotor retardation (63.6%), epilepsy (27%), and infection of respiratory system (45.5%). The concentration of folate in both serum and cerebrospinal fluid was decreased (72.7% and 63.6% respectively). Hypoimmunoglobulinemia accounted for 27.3%. Most of mutations in HFM were distributed between p. 65 and p. 68 (c.194-c.204), mainly due to insertion- or deletion-related frame shifts or generation of stop codons. Oral and parenteral folinic acid treatment was effective. Conclusion: Hereditary folate malabsorption often presented with megaloblastic anemia, abnormalities of digestive and nervous system, and hypoimmunoglobulinemia with recurrent infections. Low level of serum and CSF folate and screening SLC46A1 gene are keys to the etiologic study of the patients. Early supplement with folinic acid is beneficial to the prognosis.

[Clinical and laboratory studies on four Chinese patients with succinate-CoA ligase deficiency noticed by mild methylmalonic aciduria]

OBJECTIVE

To study the clinical and genetic features of the patients with secondary methylmalonic aciduria due to succinate-CoA ligase deficiency.

METHOD

From February 2011 to April 2014, 4 Chinese patients with succinate-CoA ligase deficiency and mild methylmalonic aciduria were enrolled in this study. The clinical course, biochemical features, brain MRI findings, and mutations were analyzed.

RESULT

Four patients presented with severe psychomotor retardation, hypotonia, seizures, feeding problems and failure to thrive from the age of one day to 6 months. Three of them had intractable epilepsies. One had hearing defect. Mild methylmalonic aciduria was detected by elevated urine methylmalonic acid and blood propionylcarnitine at the age of 6 months to 2 years and 8 months. Five mutations, c. 550G>A, c. 751C>T, c. 809A>C, c. 961C>G and c. 826-2A>G in SUCLG1 of three patients were identified. On SUCLA2, one novel mutation, c. 970C>T, was found in one patient. After treatment, the disease in all four patients was improved.

CONCLUSION

Four Chinese patients with succinyl-CoA ligase deficiency caused by SUCLG1 and SUCLA2 mutations were noticed by mild methylmalonic aciduria and diagnosed using high-throughput genomic sequencing. Succinate-CoA ligase deficiency is a rare cause of methylmalonic aciduria. Biochemical and gene studies are necessary for the differential diagnoses.

Preparation of High-Efficiency Cytochrome c-Imprinted Polymer on the Surface of Magnetic Carbon Nanotubes by Epitope Approach via Metal Chelation and Six-Membered Ring

A novel epitope molecularly imprinted polymer on the surface of magnetic carbon nanotubes (MCNTs@EMIP) was successfully fabricated to specifically recognize target protein cytochrome c (Cyt C) with high performance. The peptides sequences corresponding to the surface-exposed C-terminus domains of Cyt C was selected as epitope template molecule, and commercially available zinc acrylate and ethylene glycol dimethacrylate (EGDMA) were employed as functional monomer and cross-linker, respectively, to synthesize MIP via free radical polymerization. The epitope was immobilized via metal chelation and six-membered ring formed between the functional monomer and the hydroxyl and amino groups of the epitope. The resulting MCNTs@EMIP exhibited specific recognition ability toward target Cyt C including more satisfactory imprinting factor (about 11.7) than that of other reported imprinting methods. In addition, the MCNTs@EMIP demonstrated a high adsorption amount (about 780.0 mg g(-1)) and excellent selectivity. Besides, the magnetic property of the support material made the processes easy and highly efficient by assistance of an external magnetic field. High-performance liquid chromatography analysis of Cyt C in bovine blood real sample and protein mixture indicated that the specificity was not affected by other competitive proteins, which forcefully stated that the MCNTs@EMIP had potential to be applied in bioseparation area. In brief, this study provided a new protocol to detect target protein in complex sample via epitope imprinting approach and surface imprinting strategy.

[Psychomotor retardation and intermitent convulsions for 8 months in an infant]

This study reports a boy with psychomotor retardation and epilepsy due to maternal phenylketonuria (PKU). The boy was admitted at the age of 20 months because of psychomotor retardation and epilepsy. He had seizures from the age of 1 year. His development quotient was 43. He presented with microcephaly, normal skin and hair color. Brain MRI scan showed mild cerebral white matter demyelination, broadening bilateral lateral ventricle and foramen magnum stricture. Chromosome karyotype, urine organic acids, blood amino acids and acylcarnitines were normal. His mother had mental retardation from her childhood. She presented with learning difficulties and yellow hair. Her premarriage health examinations were normal. She married a healthy man at age of 26 years. When she visited us at 28 years old, PKU was found by markedly elevated blood phenylalanine (916.54 μmol/L vs normal range 20-120 μmol/L). On her phenylalanine hydroxylase (PAH) gene, a homozygous mutations c.611A>G (p.Y204C) was identified, which confirmed the diagnosis of PAH-deficient PKU. Her child carries a heterozygous mutation c.611A>G with normal blood phenylalanine. Her husband had no any mutation on PAH. It is concluded that family investigation is very important for the etiological diagnosis of the children with mental retardation and epilepsy. Carefully clinical and metabolic survey should be performed for the parents with mental problems to identify parental diseases-associated child brain damage, such as maternal PKU.

[Psychomotor retardation and intermitent convulsions for 8 months in an infant]

This study reports a boy with psychomotor retardation and epilepsy due to maternal phenylketonuria (PKU). The boy was admitted at the age of 20 months because of psychomotor retardation and epilepsy. He had seizures from the age of 1 year. His development quotient was 43. He presented with microcephaly, normal skin and hair color. Brain MRI scan showed mild cerebral white matter demyelination, broadening bilateral lateral ventricle and foramen magnum stricture. Chromosome karyotype, urine organic acids, blood amino acids and acylcarnitines were normal. His mother had mental retardation from her childhood. She presented with learning difficulties and yellow hair. Her premarriage health examinations were normal. She married a healthy man at age of 26 years. When she visited us at 28 years old, PKU was found by markedly elevated blood phenylalanine (916.54 μmol/L vs normal range 20-120 μmol/L). On her phenylalanine hydroxylase (PAH) gene, a homozygous mutations c.611A>G (p.Y204C) was identified, which confirmed the diagnosis of PAH-deficient PKU. Her child carries a heterozygous mutation c.611A>G with normal blood phenylalanine. Her husband had no any mutation on PAH. It is concluded that family investigation is very important for the etiological diagnosis of the children with mental retardation and epilepsy. Carefully clinical and metabolic survey should be performed for the parents with mental problems to identify parental diseases-associated child brain damage, such as maternal PKU.

A "turn-on" fluorescent receptor for detecting tyrosine phosphopeptide using the surface imprinting procedure and the epitope approach

A new strategy for the manufacture of a turn-on fluorescent molecularly imprinted polymer (CdTe/SiO2/MIP) receptor for detecting tyrosine phosphopeptide (pTyr peptide) was proposed. The receptor was prepared by the surface imprinting procedure and the epitope approach with silica-capped CdTe quantum dots (QDs) as core substrate and fluorescent signal, phenylphosphonic acid (PPA) as the dummy template, 1-[3-(trimethoxysilyl) propyl] urea as the functional monomer, and octyltrimethoxysilane as the cross-linker. The synthetic CdTe/SiO2/MIP was able to selectively capture the template PPA and corresponding target pTyr peptide with fluorescence enhancement via the special interaction between them and the recognition cavities. The receptor exhibited the linear fluorescence enhancement to pTyr peptide in the range of 0.5-35μM, and the detection limit was 0.37μM. The precision for five replicate detections of pTyr peptide at 20μM was 2.60% (relative standard deviation). Combining the fluorescence property of the CdTe QDs with the merits of the surface imprinting technique and the epitope approach, the receptor not only owned high recognition site accessibility and good binding affinities for target pTyr peptide, but also improved the fluorescence selectivity of the CdTe QDs, as well revealed the feasibility of fabrication of a turn-on fluorescence probe using the surface imprinting procedure and the epitope approach.

Development of automated online gel permeation chromatography–gas chromatograph mass spectrometry for measuring multiresidual pesticides in agricultural products

An automated online gel permeation chromatography-gas chromatograph mass spectrometer (GPC-GC/MS) was developed for the rapid determination of residual pesticides in agricultural products. Pesticides were extracted from homogenized food samples with acetonitrile and decontaminated via the matrix solid-phase dispersion (MSPD) technique, using a primary secondary amine as sorbent prior to GPC-GC/MS analysis. A slightly modified preparation method and automated GPC step proved useful in minimizing matrix interference. To evaluate the performance of the system, 97 target pesticides were spiked at a concentration of 0.1mg/kg into a range of food types, including potato, cabbage, carrot, apple, orange, cucumber, and rice. A low flow rate of 0.1 mL/min in GPC resulted in a 40-fold reduction in solvent consumption compared with conventional GPC column applications. The combination of MSPD technique and GPC-GC/MS for the analysis of the 97 pesticides can be accomplished within 90 min. Most pesticides were recovered in the range of 70-120%, with relative standard deviation generally less than 10%. The results demonstrate that the method can be successfully applied with acceptable recoveries to a broad range of target pesticides within a diverse range of food types.