Single-port endoscopic-sentinel lymph node biopsy combined with indocyanine green and carbon nanoparticles in breast cancer.

BACKGROUND: In order to explore the surgical safety and the reliability of axillary staging of single-port endoscopic-sentinel lymph node biopsy, we combined it with indocyanine green that was excited by near-infrared fluorescence endoscopy and carbon nanoparticles as a tracer and compared this method to conventional open sentinel lymph node biopsy. METHODS: This is a retrospective and observational study, there were 20 patients in each group and the total sample size was 60: Group 1, single-port endoscopic-sentinel lymph node biopsy combined with indocyanine green and carbon nanoparticles; Group 2, single-port endoscopic-sentinel lymph node biopsy with carbon nanoparticles only; Group 3, conventional sentinel lymph node biopsy with indocyanine green and carbon nanoparticles. Sentinel lymph node detection and upper extremity function were determined to measure the safety and efficacy of the novel single-port endoscopic-sentinel lymph node biopsy (SPE-SLNB) technique to the standard conventional sentinel lymph node biopsy technique. RESULTS: The detection rate of sentinel lymph nodes was 100% in Group 1, 100% in Group 2, and 95% in Group 3. There were no significant differences in upper arm function and pain scores between the three groups. CONCLUSION: The novel technique of combining indocyanine green and carbon nanoparticles with single-port endoscopic-sentinel lymph node biopsy achieved a similar detection rate and mean number of sentinel lymph nodes as conventional sentinel lymph node biopsy. Traditional open surgery requires two different incisions for breast surgery and SLNB. While the most important advantage of SPE-SLNB is that two procedures can be effectively performed through a single-port in the axilla Therefore, for patients who meet the indications, single-port endoscopic-sentinel lymph node biopsy is as safe and reliable as conventional sentinel lymph node biopsy but has the aesthetic advantage of only one incision.

Comparing outcomes of single-port insufflation endoscopic breast-conserving surgery and conventional open approach for breast cancer.

BACKGROUND: In the surgical treatment of breast cancer, the goal of surgeons is to continually create and improve minimally invasive surgical techniques to increase patients' quality of life. Currently, routine breast-conserving surgery is often performed using two obvious incisions. Here, we compare the clinical efficacy and aesthetic outcomes of a novel technique using one incision, called 'single-port insufflation endoscopic breast-conserving surgery' (SIE-BCS), vs. conventional breast-conserving surgery (C-BCS) in patients with early-stage breast cancer. METHODS: A total of 180 patients with stage I or stage II breast cancer participated in this study, of whom 63 underwent SIE-BCS and 117 underwent C-BCS. Logistic regression analysis was conducted to assess the risk of local recurrence and metastasis. Aesthetic outcomes were evaluated using the BREAST-Q scale. RESULTS: The mean operation time was significantly longer for SIE-BCS (194.9 ± 71.5 min) than for C-BCS (140.3 ± 56.9 min), but the mean incision length was significantly shorter for SIE-BCS than for C-BCS (3.4 ± 1.2 cm vs. 8.6 ± 2.3 cm). While both surgeries yielded similar BREAST-Q ratings for satisfaction with breasts and sexual well-being, SIE-BCS was associated with significantly better ratings for physical well-being (chest area) and psychological well-being. Additionally, SIE-BCS was associated with decreased rates of adverse effects of radiation. The preliminary analysis showed that SIE-BCS did not increase the risk of local recurrence or metastasis. CONCLUSION: The novel single-port insufflation endoscopic assisted BCS technique is feasible, safe, and improves patients' postoperative comfort and psychological well-being, as compared to the conventional technique.

Rational design and synthesis of magnetic covalent organic frameworks for controlling the selectivity and enhancing the extraction efficiency of polycyclic aromatic hydrocarbons.

A series of three-dimensional magnetic covalent organic frameworks were designed and synthesized via monomer selection, coating thickness optimization, and composite strategy transformation. Their structure properties including morphology, functional group, surface area, and pore size were characterized. The relationship between the structural properties and analytical performance was systematically investigated by density functional theory calculation and batch extraction experiments for polycyclic aromatic hydrocarbons. It is proven that the extractant modified by monomer 1,4-phthalaldehyde provides a hizgh affinity for high molecule weight polycyclic aromatic hydrocarbons and the right balance between extraction and elution efficiency. The relationship between coating thickness and mass transfer rate of polycyclic aromatic hydrocarbons was studied by accurate tuning of coating layers via layer-by-layer method. A mathematical model was derived and employed to determine that two coating layers were sufficient to provide the highest extraction efficiency with the shortest equilibrium time. The extractants synthesized by two different composite strategies (layer-by-layer and one-step) show opposite selectivity for polycyclic aromatic hydrocarbons. After optimization of the extraction conditions, dispersed solid-phase extraction coupled with gas chromatography-mass spectroscopy method was developed providing a wide linear range (5-500 ng L-1), good linearity (R2 > 0.9923), high precision in intra-day (RSD% < 8.2%) and inter-day (RSD% < 12.3%) detection, and low detection limits (1.5-15.1 ng L-1). The method was applied to the simultaneous determination of 16 polycyclic aromatic hydrocarbons with acceptable recoveries, which were 87-109% for groundwater, 83-116% for East Lake water, and 82-116% for Yangtze River water samples.

Electrospun highly ordered mesoporous silica-carbon composite nanofibers for rapid extraction and prefractionation of endogenous peptides.

A simple method was developed for the preparation of ordered mesoporous silica-carbon composite nanofibers (OMSCFs). The OMSCFs exhibited high carbon content, continuously long fibrous properties, uniform accessible mesopores, and a large surface area. The OMSCFs were also found to have ion-exchange capacity. On the basis of the size-exclusion effect of the mesopores and mixed-mode hydrophobic/ion-exchange interactions, the OMSCFs were applied for rapid enrichment of endogenous peptides by using a miniaturized solid-phase extraction format. The adsorption mechanism was studied, and the eluting solution was optimized with standard peptide/protein solutions and protein digests. Employing a successive three-step elution strategy, followed by LC-MS/MS analysis, led to excellent performance with this approach in the extraction and prefractionation of peptides from human serum.

In-syringe dispersive solid phase extraction: a novel format for electrospun fiber based microextraction.

A novel in-syringe dispersive solid phase extraction (dSPE) system using electrospun silica fibers as adsorbents has been developed in the current work. A few milligrams of electrospun silica fibers were incubated in sample solution in the barrel of a syringe for microextraction assisted by vortex. Due to the benefit of dispersion and the high mass transfer rate of the sub-microscale electrospun silica fibers, the extraction equilibrium was achieved in a very short time (less than 1 min). Moreover, thanks to the long fibrous properties of electrospun fibers, the separation of the adsorbent from sample solution was easily achieved by pushing out the sample solution which therefore simplified the sample pretreatment procedure. Besides, the analytical throughput was largely increased by using a multi-syringe plate to perform the extraction experiment. The performance of the in-syringe dSPE device was evaluated by extraction of endogenous cytokinins from plant tissue samples based on the hydrophilic interaction. Six endogenous cytokinins in 20 mg of Oryza sativa L. (O. sativa) leaves were successfully determined under optimized conditions using in-syringe dSPE combined with liquid chromatography-mass spectrometry analysis. The results demonstrated that the in-syringe dSPE method was a rapid and high-throughput strategy for the extraction of target compounds, which has great potential in microscale sample pretreatment using electrospun fibers.

Rapid enrichment of phosphopeptides by SiO2-TiO2 composite fibers.

SiO2-TiO2 composite fibers, prepared by electrospinning, were successfully applied to the rapid enrichment of phosphopeptides using a lab-in-syringe approach for the first time. Because of their large surface area, mesoporous structure, extraordinary length and appropriate Lewis acidity, the as-prepared SiO2-TiO2 composite fibers exhibited high selectivity and capacity in the enrichment of phosphopeptides from the digestion mixture of ß-casein and bovine serum albumin (BSA), as well as human blood serum and nonfat milk. The targeted phosphopeptides could be easily enriched and detected even when the total amount of ß-casein was decreased to only 10 fmol, indicating the high detection sensitivity of this method. In addition, the whole enrichment extraction procedure can be finished in less than 3 min, which can avoid or decrease the degradation of endogenous phosphoproteins by proteases released ex vivo during time-consuming treatments. The developed method is rapid, cost-effective, selective, sensitive, operationally simple, and does not require any harsh conditions and intricate equipment, providing an ideal candidate for the enrichment of phosphopeptides from complex biological samples either in the lab or in the field.

Zirconium arsenate-modified magnetic nanoparticles: preparation, characterization and application to the enrichment of phosphopeptides.

Phosphorylation, one of the most important post-translational modifications of protein, plays a crucial role in a large number of biological processes. Large-scale identification of protein phosphorylation by mass spectrometry is still a challenging task because of the low abundance of phosphopeptides and sub-stoichiometry of phosphorylation. In this work, a novel strategy based on the specific affinity of zirconium arsenate to the phosphate group has been developed for the effective enrichment of phosphopeptides. Zirconium arsenate-modified magnetic nanoparticles (ZrAs-Fe(3)O(4)@SiO(2)) were prepared by covalent immobilization of zirconium arsenate on Fe(3)O(4)@SiO(2) magnetic nanoparticles under mild conditions, and characterized by transmission electron microscope (TEM), Fourier transform infrared (FT-IR) spectroscopy, energy dispersive X-ray spectroscopy (EDX) and vibrating sample magnetometer (VSM). The prepared ZrAs-Fe(3)O(4)@SiO(2) was applied for the selective enrichment of phosphopeptides from the digestion mixture of phosphoproteins and bovine serum albumin (BSA). Our results demonstrated that the ZrAs-Fe(3)O(4)@SiO(2) magnetic nanoparticles possess higher selectivity for phosphopeptides and better capture capability towards multiply-phosphorylated peptides than commercial zirconium dioxide (ZrO(2)), which has been widely employed for the enrichment of phosphopeptides. In addition, endogenous phosphopeptides from human serum can be effectively captured by ZrAs-Fe(3)O(4)@SiO(2) magnetic nanoparticles. It is the first report, to the best of our knowledge, in which the zirconium arsenate-modified magnetic nanoparticles were successfully applied to the enrichment of phosphopeptides, which offers the potential application of this new material in phosphoproteomics study.

Titanium-containing magnetic mesoporous silica spheres: effective enrichment of peptides and simultaneous separation of nonphosphopeptides and phosphopeptides.

Protein phosphorylation is a common posttranslational modification, and involved in many cellular processes. Like endogenous peptides, endogenous phosphopeptides contain many biomarkers of preclinical screening and disease diagnosis. In this work, titanium-containing magnetic mesoporous silica spheres were synthesized and applied for effective enrichment of peptides from both tryptic digests of standard proteins and human serum. Besides, the enriched peptides can be further separated into nonphosphopeptides and phosphopeptides by a simple elution. First, titanium-containing magnetic mesoporous silica spheres were synthesized by a sol-gel method and found to have high surface area, narrow pore size distribution, and useful magnetic responsivity. Then, as the prepared material was used for selective capturing of phosphopeptides, it demonstrated to have higher selectivity than commercial titanium dioxide. Moreover, via combination of size-exclusion mechanism, hydrophobic interaction, and affinity chromatography, titanium-containing magnetic mesoporous silica spheres were successfully applied to simultaneously extract and separate nonphosphopeptides and phosphopeptides from standard protein digestion and human serum.

Recent global warming as a proximate cause of deforestation and forest degradation in northern Pakistan.

Instrumental climatological records such as weather stations data of northern areas of Pakistan are not sufficient to assess the forest extreme events reliably. To understand the past climatic variability, tree ring width based climatic reconstruction is the best alternative to trace climate variability that goes back in time. Quercus Incana is the most sensitive species to drought and climatic variation in northern Pakistan. However, very little research quantifies the rate of ongoing climatic changes. A total of 65 tree cores were collected from two sites to understand the radial growth of Q. Incana to extreme drought events. The radial growth is mainly affected by high temperatures during May-July. In addition, radial growth exhibits a positive correlation with February-June precipitation while it is negatively correlated with the September precipitation. The radial growth decrease, particularly in harsh climatic conditions. The reconstructed tree ring record was strongly coherent with the May-June self-calibrated Palmer drought severity index (scPDSI) and reliable in reconstructing drought variability for the period 1750-2014. During the past 264 years, wet periods were found during 1980-2010, 1812-1836, and 1754-1760, while dry periods were found during 1896-1922, 1864-1876, and 1784-1788. Our reconstruction explains 39.8% of the scPDSI variance. The extreme drought and wet years we arrived at were in close agreement with the drought and wet periods that occurred in northern Pakistan. Wavelet analysis revealed drought variability at periodicities of 2.2-2.5, 3.3, 3-4, 16.7, 16.8, and 68-78.8 years. Hence it is concluded that deforestation and forest degradation rate increased with extreme drought and wet years. Overall, the variation of drought in northern Pakistan seems to have been affected due to El Nino south oscillation, Pacific decadal oscillation, or Atlantic multi-decadal oscillations.

Oncological outcome of single-port insufflation endoscopic nipple-sparing mastectomy versus open mastectomy in early breast cancer patients: a study protocol for a randomised controlled trial.

INTRODUCTION: Breast cancer is the most prevalent cancer and the leading cause of cancer-related death in women. Conventional open mastectomy (C-OM) is one of the most common procedures for breast cancer, which involves the removal of the nipple-areola complex and a large proportion of the breast skin, leading to poor cosmetic effect and restriction of upper extremity function. Single-port insufflation endoscopic nipple-sparing mastectomy (SIE-NSM) could conceal the incision along the wrinkles in the axilla, preserve all the breast skin and nipple-areola complex and provide a better cosmetic outcome and quality of life. This trial aims to investigate the oncological safety between SIE-NSM and C-OM in early breast cancer patients. METHODS AND ANALYSIS: This is a single centre, non-blinded, randomised controlled trial (RCT) and will be conducted at Beijing Friendship Hospital. Patients will be enrolled in the inpatient ward. Breast surgeons will notify patients who meet the inclusion and exclusion criteria with the instruction of this RCT. Patients will be randomly assigned to C-OM or SIE-NSM with a 3:1 allocation as per a computer-generated randomisation schedule. Patients will be followed-up for 12 months for analysing surgical outcomes. The primary outcome is the local recurrence rate at a 12-month follow-up. The secondary outcome is the distant metastasis rate, cosmetic satisfaction score and psychosocial well-being score after a 12-month follow-up. To ensure the accuracy of the cosmetic satisfaction score and psychosocial well-being score, the standard scale, Breast-Q score, will be applied. ETHICS AND DISSEMINATION: This study will be conducted according to the medical ethics committee of the Beijing Friendship Hospital and according to the principles of the Declaration of Helsinki. All patients will receive clear instruction of their disease and treatment plan. Informed consent will be obtained from all patients when they agree to comply with our research plan. The results will be disseminated at academic presentations and publications in peer-reviewed journals. The raw data will be confidentially stored in our electronic data capture database. Data will not be shared unless an appropriate data request is submitted after the trial completion and peer-review journal publication. TRIAL REGISTRATION NUMBER: NCT04461847.

Magnetic nanoparticle assembly on surfaces using click chemistry.

Controlled assembly of ferromagnetic nanoparticles on surfaces is of crucial importance for a range of spintronic and data storage applications. Here, we present a novel method for assembling monolayers of ferromagnetic FePt nanoparticles on silicon oxide substrates using "click chemistry". Reaction of alkyne-functionalized FePt nanoparticles with azide-terminated self-assembled monolayers (SAMs), on silicon oxide, leads to the irreversible attachment of magnetic nanoparticles to the surface via triazole linkers. Based on this covalent interaction, well-packed monolayers of FePt nanoparticles were prepared and nanoparticle patterns are generated on surfaces via microcontact printing (µCP).

Low-temperature solution synthesis of chemically functional ferromagnetic FePtAu nanoparticles.

Magnetic nanoparticles are of great scientific and technological interest. The application of ferromagnetic nanoparticles for high-density data storage has great potential, but energy efficient synthesis of uniform, isolated, and patternable nanoparticles that remain ferromagnetic at room temperature is not trivial. Here, we present a low-temperature solution synthesis method for FePtAu nanoparticles that addresses all those issues and therefore can be regarded as an important step toward applications. We show that the onset of the chemically ordered face-centered tetragonal (L1(0)) phase is obtained for thermal annealing temperatures as low as 150 degrees C. Large uniaxial magnetic anisotropy (10(7) erg/cm(3)) and a high long-range order parameter have been obtained. Our low-temperature solution annealing leaves the organic ligands intact, so that the possibility for postanneal monolayer formation and chemically assisted patterning on a surface is maintained.

Monolayer-directed assembly and magnetic properties of FePt nanoparticles on patterned aluminum oxide.

FePt nanoparticles (NPs) were assembled on aluminum oxide substrates, and their ferromagnetic properties were studied before and after thermal annealing. For the first time, phosph(on)ates were used as an adsorbate to form self-assembled monolayers (SAMs) on alumina to direct the assembly of NPs onto the surface. The Al(2)O(3) substrates were functionalized with aminobutylphosphonic acid (ABP) or phosphonoundecanoic acid (PNDA) SAMs or with poly(ethyleneimine) (PEI) as a reference. FePt NPs assembled on all of these monolayers, but much less on unmodified Al(2)O(3), which shows that ligand exchange at the NPs is the most likely mechanism of attachment. Proper modification of the Al(2)O(3) surface and controlling the immersion time of the modified Al(2)O(3) substrates into the FePt NP solution resulted in FePt NPs assembly with controlled NP density. Alumina substrates were patterned by microcontact printing using aminobutylphosphonic acid as the ink, allowing local NP assembly. Thermal annealing under reducing conditions (96%N(2)/4%H(2)) led to a phase change of the FePt NPs from the disordered FCC phase to the ordered FCT phase. This resulted in ferromagnetic behavior at room temperature. Such a process can potentially be applied in the fabrication of spintronic devices.

Eco-friendly and facile one-step synthesis of a three dimensional net-like magnetic mesoporous carbon derived from wastepaper as a renewable adsorbent.

Millions of tons of paper and its derivatives are annually wasted without being recycled and reused. To promote the comprehensive utilization of resources and eco-friendly preparation, waste filter paper, printer paper, and napkins were chosen as carbon sources to one-step synthesize three types of three dimensional (3D) net-like magnetic mesoporous carbon (MMC) by an eco-friendly and low-cost method. These mesoporous (3.90-7.68 nm) composites have a high specific surface area (287-423 m2 g-1), well-developed porosity (0.24-0.74 cm3 g-1) and abundant oxygen-containing functional groups. Compared to the other two composites, the adsorbent derived from filter paper showed the highest adsorption capacity towards methylene blue (MB) (q max = 332.03 mg g-1) and rhodamine B (RhB) (q max = 389.59 mg g-1) with a high adsorption rate (<5 min). According to the effect of pH value on adsorption capacity, and combining the analysis of Fourier transform infrared spectrometry and X-ray photoelectron spectroscopy, the main adsorption mechanisms can be summarized as hydrogen bonds, electrostatic interactions, and π-π interaction. Besides, the occurrence of redox reactions between Fe2+/Fe0 and dye cannot be ignored. Finally, experiments on reusability were performed. They showed that the 3D net-like MMC could be easily regenerated and still maintained a removal efficiency of above 80% for RhB and 90% for MB after five cycles.

Porphyrin-based magnetic nanocomposites for efficient extraction of polycyclic aromatic hydrocarbons from water samples.

Stable and reusable porphyrin-based magnetic nanocomposites were successfully synthesized for efficient extraction of polycyclic aromatic hydrocarbons (PAHs) from environmental water samples. Meso-Tetra (4-carboxyphenyl) porphyrin (TCPP), a kind of porphyrin, can connect the copolymer after amidation and was linked to Fe3O4@SiO2 magnetic nanospheres via cross-coupling. Several characteristic techniques such as field emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectrometry, vibrating sample magnetometry and a tensiometer were used to characterize the as-synthesized materials. The structure of the copolymer was similar to that of graphene, possessing sp2-conjugated carbon rings, but with an appropriate amount of delocalized π-electrons giving rise to the higher extraction efficiency for heavy PAHs without sacrificing the performance in the extraction of light PAHs. Six extraction parameters, including the TCPP:Fe3O4@SiO2 (m:m) ratio, the amount of adsorbents, the type of desorption solvent, the desorption solvent volume, the adsorption time and the desorption time, were investigated. After the optimization of extraction conditions, a comparison of the extraction efficiency of Fe3O4@SiO2-TCPP and Fe3O4@SiO2@GO was carried out. The adsorption mechanism of TCPP to PAHs was studied by first-principles density functional theory (DFT) calculations. Combining experimental and calculated results, it was shown that the π-π stacking interaction was the main adsorption mechanism of TCPP for PAHs and that the amount of delocalized π-electrons plays an important role in the elution process. Under the optimal conditions, Fe3O4@SiO2-porphyrin showed good precision in intra-day (<8.9%) and inter-day (<13.0%) detection, low method detection limits (2-10 ng L-1), and wide linearity (10-10000 ng L-1). The method was applied to simultaneous analysis of 15 PAHs with acceptable recoveries, which were 71.1%-106.0% for ground water samples and 73.7%-107.1% for Yangtze River water samples, respectively.

Magnetic extractant with an Fe3O4@SiO2 core and aqueous ammonia coating for microextraction of petroleum acids.

Magnetic aqueous ammonia (MAA) was prepared as a magnetic extractant for dispersive microextraction of petroleum acids (PAs). The amount of extractant in MAA was custom-made by a simple approach. In the MAA composed of an aqueous ammonia coating and Fe3O4@SiO2 core, the coating is a base extractant that can selectively extract acids, while the magnetic core serves as a support to achieve dispersion as well as rapid magnetic retrieval of the extractant during the extraction processes. This is the first use of reusable, stable and modifiable Fe3O4@SiO2 as a support instead of bare Fe3O4 in a magnetic particle assisted dispersive liquid-liquid microextraction technique. The parameters that affect extraction efficiency were investigated. The sampling step as well as the desorption step can be completed in 2 min. The linear ranges are 5-5000 ng g-1, while the limits of quantification range from 2.5 to 6.2 ng g-1. The recoveries in spiked crude oil samples are in the range of 79.1% to 112.1% with relative standard deviations less than 11.3% (intra-day) and 13.4% (inter-day). Finally, the proposed method was applied to the analysis of PAs in diluted crude oils with different maturities. In comparison to the existing methods for extraction of PAs, the proposed method provides superior performances including high throughput (12-well plate), high degree of sample clean-up, and low consumption of separation material, solvent and time.

Hydrothermally tailor-made chitosan fiber for micro-solid phase extraction of petroleum acids in crude oils.

Tailor-made chitosan fiber was prepared via hydrothermal treatment to serve as a micro-solid phase extraction (micro-SPE) sorbent for the analysis of petroleum acids (PAs) in crude oils. Chitosan fiber, which is commercial and cheap, has a diameter of about 10 µm and a length of a few centimeters. The fibrous property of the sorbent enables the micro-SPE to deal with viscous crude oil samples because of the low back-pressure during extraction, while the abundant hydroxyl groups and amino groups on the surface of chitosan fiber can provide high density of specific sites for adsorption of PAs. Moreover, it was found that hydrothermal treatment at certain conditions could tune the surface properties of chitosan fiber, leading to significant improvement of the capacity of the fiber in adsorption of PAs. Using hydrothermally treated chitosan fiber as sorbent, the micro-SPE was applied to the determination of PAs in crude oils, with the advantages of easy-operation, rapidness and high sensitivity (the limits of detection range from 0.7 ng/g to 5.4 ng/g). Furthermore, coupled with comprehensive two dimensional gas chromatography-mass spectrometry (GC × GCMS), the treated chitosan fiber packed micro-SPE method showed a great potential for comprehensive profiling of PAs in crude oils.

Polyoxometalate incorporated polymer monolith microextraction for highly selective extraction of antidepressants in undiluted urine.

In this work, a polyoxometalate (POM) incorporated polymer monolith microextraction (PMME) was successfully proposed and employed in the selective extraction of basic antidepressants in undiluted urine sample. This hybrid monolith exhibited strong cation-exchange interaction (SCX) with positively charged antidepressants when pH was 3.0, because of the multiple ionizable moieties on polyanionic POM. As such, antidepressants in complex sample matrices were efficiently extracted by the monolith, and the matrix effect was significantly reduced. In addition, due to the high amount of anionic POM, the monolith exhibited remarkable extraction capacities for target antidepressants ranging from 4.7 to 5.8mg/g. Further, the POM incorporated PMME was coupled with high-performance liquid chromatography-ultraviolet (HPLC-UV). Thus, antidepressants in undiluted urine sample was efficiently extracted under optimized extraction conditions online. The limits of detection (LODs) for the target antidepressants ranged from 0.7 to 1.4ng/mL, and the linear range was 5-1000ng/mL with determination coefficients (R2) higher than 0.9960. The recoveries ranged from 86.8% to 104.0% with relative standard deviations (RSDs) of 0.4-10.1%. The proposed procedure was successfully applied to determine antidepressant in human urine. Taken together, the developed method presented a new strategy for the analysis of basic drugs in undiluted urine sample, which could be used for monitoring medicines in pharmacokinetic analysis.

Pyridoxal 5'-phosphate mediated preparation of immobilized metal affinity material for highly selective and sensitive enrichment of phosphopeptides.

Phosphorylation is a crucial post-translational modification, which plays pivotal roles in various biological processes. Analysis of phosphopeptides by mass spectrometry (MS) is intractable on account of their low stoichiometry and the ion suppression from non-phosphopeptides. Thus, enrichment of phosphopeptides before MS analysis is indispensable. In this work, we employed pyridoxal 5'-phosphate (PLP), as an immobilized metal affinity chromatography (IMAC) ligand for the enrichment of phosphopeptides. PLP was grafted onto several substrates such as silica (SiO2), oxidized carbon nanotube (OCNT) and silica coated magnetic nanoparticles (Fe3O4@SiO2). Then the metal ions Fe3+, Ga3+ and Ti4+ were incorporated for the selective enrichment of phosphopeptides. It is indicated that Fe3O4@SiO2-PLP-Ti4+ has a superior selectivity towards phosphopeptides under as much as 1000-fold interferences of non-phosphopeptides. Further, Fe3O4@SiO2-PLP-Ti4+ exhibited high efficiency in selective enrichments of phosphopeptides from complex biological samples, including human serum and tryptic digested non-fat milk. Finally, Fe3O4@SiO2-PLP-Ti4+ was successfully employed in the sample pretreatment for profiling phosphopeptides in a tryptic digest of rat brain proteins. Our experimental results evidenced a great potential of this new chelator-based material in phosphoproteomics study.

Determination of diamondoids in crude oils using gas purge microsyringe extraction with comprehensive two dimensional gas chromatography-time-of-flight mass spectrometry.

Based on a homemade device, gas purge microsyringe extraction (GP-MSE) of crude oil samples was developed for the first time. As a simple, fast, low-cost, sensitive and solvent-saving technique, GP-MSE provides some outstanding advantages over the widely used sample preparation methods for crude oils such as column chromatography (ASTM D2549). Several parameters affecting extraction efficiency were optimized, including extraction temperature, extraction time, extraction solvent, condensing temperature and purge gas flow rate. With the optimized GP-MSE conditions, several real crude oil samples were extracted, and trace diamondoids were determined using comprehensive two dimensional gas chromatography-time-of-flight mass spectrometry (GC×GC-TOFMS). In total, more than 100 diamondoids were detected and 27 marker compounds were identified and quantified accurately. The limits of detection (LODs, S/N=3) were less than 0.08µg/L for all diamondoids. The relative standard deviation (RSD) was below 8%, ranging from 1.1 to 7.6%. The linearity of the developed method was in the range of 0.5-100.0µg/L with correlation coefficients (R2) more than 0.996. The recoveries obtained at spiking 50µg/L were between 81 and 108% for diamondoids in crude oil samples. The developed method can also be extended to the analysis of other components in crude oils and other complex matrices.