Response surface methodology for optimization of nitrocellulose preparation from nata de coco bacterial cellulose for propellant formulation

Nitrocellulose (NC) has garnered significant interest among researchers due to its versatile applications, contingent upon the degree of nitration that modifies the cellulose structure. For instance, NC with a high nitrogen content, exceeding 12.5%, finds utility as a key ingredient in propellant formulations, while variants with lower nitrogen content prove suitable for a range of other applications, including the formulation of printing inks, varnishes, and coatings. This communication aims to present the outcomes of our efforts to optimize the nitration reaction of bacterial cellulose to produce high-nitrogen-content NC, employing the response surface methodology (RSM). Our investigation delves into the influence of the mole ratio of sulfuric and nitric acids, reaction temperature, and nitration duration on the nitrogen content of the resultant products. Utilizing a central composite design (CCD), we identified the optimal conditions for NC synthesis. Analysis of variance (ANOVA) underscored the substantial impact of these reaction conditions on the percentage of nitrogen content (%N) yield. By implementing the predicted optimal conditions-namely, a H2SO4:HNO3 mole ratio of 3:1, a reaction temperature of 35 °C, and a reaction period of 22 min-we successfully produced NC with a nitrogen content of 12.64%. Characterization of these products encompassed elemental analysis, Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), thermal gravimetric analysis (TGA), and field emission scanning electron microscopy (FESEM).

Current Trends in Validating Antibody Specificities for ELISpot by Western Blotting

The enzyme-linked immunospot (ELISpot) assay is a highly useful and sensitive method to detect total immunoglobulin and antigen-specific antibody-secreting cells. In addition, this method can measure biological activity and immunological secretions from immune cells. In general, membrane-bound antigen allows binding of antibody secreted by B cells, or a membrane-bound analyte-specific antibody binds to the specific analyte (e.g., cytokines) elicited from cells added to the well containing the bound antibody. The response from added cells is then detected by using an anti-Ig antibody and a colorimetric substrate, while in the case of non-B cells, the elicited antigen is detected with appropriate antibodies and enzyme-conjugated antibodies. Specificity of antibodies binding the protein of interest is necessary to achieve correct results. Western blotting can be used for this with/without siRNA knockdown of proteins of interest or with the use of peptide inhibitors to inhibit the binding of specific antibodies to the target protein. Despite its general simplicity, western blotting is a powerful technique for immunodetection of proteins (notably low abundance proteins) as it provides simultaneous resolution of multiple immunogenic antigens within a sample for detection by specific antibodies. Now, we have plethora of immunoblotting methods to validate antibodies for ELISpot.

A simple voltammetric method to evaluate the firing distance through determination of nitrocellulose

Nitrocellulose (NC) is the main component of propellants for small firearm ammunitions. Even though NC particles are ejected from gun barrels together with bullets and they are often recovered on close-to-muzzle targets, quantitative analysis of nitrocellulose for forensic purposes has been neglected so far. Moreover, although the presence of the nitroester groups makes nitrocellulose electroactive, its electrochemical determination has been poorly considered in literature. In this paper, a quantitative differential pulse voltammetric method for the analysis of nitrocellulose in targets is suggested, with the aim of estimating its concentration decay on targets with increasing the shooting distance. The presented method works in acetonitrile/ethanol/lithium perchlorate, has a LOQ of 4 mg L-1 and linearity up to 2000 mg L-1. Ammunitions loaded with a nitrocellulose/nitroglycerine-based gunpowder were discharged to draw a calibration curve for shooting distance determination in the range from 5 cm to 120 cm. The effect of possible interfering substances (water, nitroglycerine, nitroguanidine, nitrites) was evaluated, and results are compared with literature methods.

Microorganisms for the oxidation of nitrated cellulose in its effluents (review)

The processes of microbiological destruction of toxic and large-tonnage waste are the most attractive processes for protecting the environment. The review considers the results of studies of microbial decomposition of nitrate esters, including hardly decomposable nitrocellulose. The published data show that specific microorganisms are able to degrade nitrated cellulose compounds under both anaerobic and aerobic conditions. The most promising microorganisms in terms of the efficiency of the nitrocellulose degradation process are bacteria belonging to Desulfovibrio genera, fungi Fusarium solani and Sclerotium rolfsii, as well as their co-cultivation. Recently, the first information about the enzymes involved in the process of nitrocellulose degradation, possible mechanisms of reactions carried out by these enzymes, and the effect of electron donors and acceptors adding to the process have been obtained. Contamination of industrial wastewater with nitrocellulose leads to treatment necessity by using cost-effective, harmless methods. A combined aerobic-anaerobic system, including both bacteria and fungi, has shown hopeful results.

On the Risk of Nitrosamine Contamination During Drug Product Blister Packaging

Most N-Nitrosamine compounds are found to be genotoxic in several animal species. Some are classified as probable or possible human carcinogens and very low acceptable daily intake has been established such as 96 ng/day for N-nitrosodimethylamine (NDMA) and 26.5 ng/N-nitrosodiethylamine (NDEA). The pharmaceutical industry has considered all processing areas for potential formation or contamination of N-nitrosamine. One risk is the potential contamination of nitrosamine during drug product blister packaging using lidding foils containing nitrocellulose, and different approaches have been used by pharmaceutical companies to evaluate and mitigate this risk. Herein we share a perspective from IQ Consortium N-nitrosamine Working Group on some of the approaches and corresponding results. From these assessments, it was concluded that the risk of nitrosamine contamination during blister packaging is negligible. The approaches shared in this perspective can be incorporated into risk assessment for nitrosamine contamination during drug product packaging at other pharmaceutical companies.

A nitrocellulose/cotton fiber hybrid composite membrane for paper-based biosensor

Nitrocellulose (NC) membrane was fabricated and tested for its potential use in various paper-based biosensors for use in point-of-care testing. However, contemporary technologies are complex, expensive, non-scalable, limited by conditions, and beset with potentially adverse effects on the environment. Herein, we proposed a simple, cost-effective, scalable technology to prepare nitrocellulose/cotton fiber (NC/CF) composite membranes. The NC/CF composite membranes with a diameter of 20 cm were fabricated in 15 min using papermaking technology, which contributes to scalability in the large-scale production of these composites. Compared with existing commercial NC membranes, the NC/CF composite membrane is characterized by small pore size (3.59 ± 0.19 μm), low flow rate (156 ± 55 s/40 mm), high dry strength (up to 4.04 MPa), and wet strength (up to 0.13 MPa), adjustable hydrophilic-hydrophobic (contact angles ranged from 29 ± 4.6 to 82.8 ± 2.4°), the good adsorption capacity of protein (up to 91.92 ± 0.07 μg). After lateral flow assays (LFAs) detection, the limit of detection is 1 nM, which is similar to commercial NC membrane (Sartorius CN 140). We envision the NC/CF composite membrane as a promising material for paper-based biosensors of point-of-care testing applications.

Validating Antibody Specificities for Immunohistochemistry by Protein Blotting

Optimized antibody reagents are important in research, and erratic antibody performance leads to variability in immunoassays. Specificity of antibodies binding the protein of interest is vital to obtain accurate results. Recommendations for validation and use of primary antibodies are unique to each type of immunoassay as the antibodies' performance is greatly affected by the assay context. Immunoblotting procedures have been used along with other important antibody-based detection methods like enzyme-linked immunosorbent assay and immunohistochemistry to confirm results in research and diagnostic testing. Specificity of antibodies employed for immunohistochemical studies is of critical importance. Therefore, the use of western blotting is imperative to address the specificity of antibodies with/without siRNA knockdown of proteins of interest or with the use of peptide inhibitors to inhibit the binding of specific antibodies to the target protein. In spite of its overall simplicity, western blotting or protein blotting is a powerful procedure for immunodetection of proteins, especially those that are of low abundance, following electrophoretic separation. The usefulness of this procedure stems from its ability to provide simultaneous resolution of multiple immunogenic antigens within a sample for detection by specific antibodies. Protein blotting has evolved greatly over the last few decades, and researchers have a variety of ways and means to carry out this procedure to validate antibodies for immunohistochemistry.

A simple and safe approach for simultaneous spectrophotometric determination of nitroglycerin and nitrocellulose in double base solid propellants

An accurate, simple and safe method was developed for simultaneous determination of nitroglycerine (NG) and nitrocellulose (NC) in double base solid propellants (DB propellants). The proposed method is based on alkaline hydrolysis of NG and NC, and followed by colored reaction of released nitrite ion with p-nitroaniline in the presence of diphenylamine in acidic media and produce azo dye. The absorbance of the azo dye was measured at 534 nm. Two sets of reaction conditions were developed. In the first set, at room temperature, only NG was hydrolyzed and calibration curve obtained. In the second set, at 60 ℃, NG and NC were hydrolyzed simultaneously. Based on obtained amount for the NG at room temperature, and total amount of NG and NC at 60 ℃, the amount of NC was determined by using stoichiometric equations. The calibration curve was linear over the concentration ranges of 0.2-5.0, 0.5-10 μg mL^-1 for NG and NC, respectively. The proposed method was successfully applied for the determination of NG and NC in DB propellants with good recoveries ranged from 99 to 101%, and RSD less than 2.0%. The method statistically compared based on t- and F-tests with those obtained in according to military standard method (MIL-STD-286). The results showed that the proposed method offers an accuracy and reliable approach for the determination of these compounds in DB propellants, and can be suggested as a routine method in military quality control laboratories.

Nitrocellulose redox permanganometry: A simple method for reductive capacity assessment

We propose a rapid, simple, and robust method for measurement of the reductive capacity of liquid and solid biological samples based on potassium permanganate reduction followed by trapping of manganese dioxide precipitate on a nitrocellulose membrane. Moreover, we discuss how nitrocellulose redox permanganometry (NRP) can be used for high-throughput analysis of biological samples and present HistoNRP, its modification used for detailed analysis of reductive capacity spatial distribution in tissue with preserved anatomical relations.•NRP is a rapid, cost-effective, and simple method for reductive capacity assessment•NRP is compatible with a high-throughput screening of solid and liquid biological samples•HistoNRP exploits passive diffusion slice print blotting for reductive capacity spatial analysis.

Utilization of cellulose in tobacco (Nicotiana tobacum) stalks for nitrocellulose production

This research explains the conversion of waste tobacco stalks into nitrocellulose to try to recover as much chemical potential contained in the biomass material as possible. Simple pioneering experiments were conducted using pulping tobacco stalks with a moisture content of 10.17 wt% and the soda pulping method being applied to produce cellulose pulp. The cellulose pulp was bleached using calcium hypochlorite to produce a dry white lignin-free pulp, which was subjected to nitration. The mixture used was 67% nitric acid and 98% sulphuric acid, and the acid ratio was varied between 3:7 and 7:3 v/v. Nitration time was varied between 5 and 25 min. This process produced nitrocellulose with all the various conditions. The nitrocellulose obtained with nitrogen content between 11 – 11.5% v/v was characterized using its solubility in acetone. An optimum nitrating mixture of 1:1 v/v with a nitration time of 5 min was used to produce nitrocellulose from tobacco stalks using soda pulping. The results show a great potential for tobacco farming countries to reduce their nitrocellulose import bill using this process.

DNA immobilization and detection using DNA binding proteins

The immobilization of sensing bioreceptors is a critical feature affecting the final performance of a biosensor. For DNA detection, the (strept)avidin-biotin affinity interaction is often used for the immobilization of biotin-labeled oligonucleotides or PCR amplicons. Herein, DNA binding proteins are proposed as alternative universal anchors for both DNA immobilization and detection, based on the strong and specific affinity interaction between certain DNA binding proteins and their respective dsDNA binding sites. These binding sites can be incorporated in the target DNA molecule during synthesis and by PCR, eliminating the need for post-synthesis chemical modification and resulting in lower costs. When scCro DNA binding protein was immobilized on microplates and nitrocellulose membrane, both ssDNA and dsDNA targets were successfully detected. The detection limits achieved were similar to those obtained with the streptavidin-biotin system. However, the scCro system resulted in higher signals while using less amount of protein. The adsorption properties of scCro were superior to streptavidin's, making scCro a viable alternative as an anchor biomolecule for the development of DNA assays and biosensors. Finally, a nucleic acid lateral flow assay based solely on two different DNA binding proteins, scCro and dHP, was developed for the detection of a PCR amplicon. Overall, the proposed system appears to be very promising and with potential use for multiplex detection using various DNA binding proteins with different sequence specificities. Further work is required to better understand the adsorption properties of these biomolecules on nitrocellulose, optimize the assays comprehensively, and achieve improved sensitivities.

Reverse Phase Protein Arrays

Reverse phase protein arrays (RPPA) are used to quantify proteins and protein posttranslational modifications in cellular lysates and body fluids. RPPA technology is suitable for biomarker discovery, protein pathway profiling, functional phenotype analysis, and drug discovery mechanism of action. The principles of RPPA technology are (a) immobilizing protein-containing specimens on a coated slide in discrete spots, (b) antibody recognition of proteins, (c) amplification chemistries to detect the protein-antibody complex, and (d) quantifying spot intensity. Construction of a RPPA begins with the robotic liquid transfer of protein-containing specimens from microtiter plates onto nitrocellulose-coated slides. The robotic arrayer deposits each sample as discrete spots in an array format. Specimens, controls, and calibrators are printed on each array, thus providing a complete calibrated assay on a single slide. Each RPPA slide is subsequently probed with catalyzed signal amplification chemistries and a single primary antibody, a secondary antibody, and either fluorescent or colorimetric dyes. The focus of this chapter is to describe RPPA detection and imaging using a colorimetric (diaminobenzidine (DAB)) detection strategy.

Cellulose before CELL: Historical themes

In 2020 the Cellulose and Renewable Materials Division (CELL) of the American Chemical (ACS) society celebrates its 100th anniversary. The following paper is based on a chapter from the book commissioned by the Division (Patterson, 2021). CELL is one of the most successful and dynamic Divisions in the ACS. It has evolved throughout its history to remain relevant and productive. One of its strengths is its diversity, while staying true to its founding vision. This perspective was present at its founding, and the following paper surveys the world of cellulose and renewable materials from the dawn of history to 1920. CELL has both industrial and scientific roots and has always welcomed the full range of participants from these communities. Rather than operating as separate tribes, the two groups have fostered innovations in each other. Many aspects of cellulose science and technology are discussed from antiquity to the early 20th century.

Immunoassays on thiol-ene synthetic paper generate a superior fluorescence signal

The fluorescence-based detection of biological complexes on solid substrates is widely used in microarrays and lateral flow tests. Here, we investigate thiol-ene micropillar scaffold sheets ("synthetic paper") as the solid substrate in such assays. Compared to state-of-the-art glass and nitrocellulose substrates, assays on synthetic paper provide a stronger fluorescence signal, similar or better reproducibility, lower limit of detection (LOD), and the possibility of working with lower immunoreagent concentrations. Using synthetic paper, we detected the antibiotic enrofloxacin in whole milk with a LOD of 1.64 nM, which is on par or better than the values obtained with other common tests, and much lower than the maximum level allowed by European Union regulations. The significance of these results lays in that they indicate that synthetically-derived microstructured substrate materials have the potential to improve the performance of diagnostic assays.

Novel fullerene-based stabilizer for scavenging nitroxide radicals and its behavior during thermal decomposition of nitrocellulose

The safe storage of double-based propellants is becoming increasingly challenging due to the extreme storage environment and update of weapon system. Therefore, to obtain high performance stabilizers, a novel multifunctional fullerene derivative, 4,11,15,30-tetramethophenyl fullereno[1,2:2',3']dihydrobenzofuran (C₆₀-DBTMP), was successfully designed and synthesized. The results of thermal stability indicated that the stability of C₆₀-DBTMP is better than that of traditional stabilizers (DPA, C2, AKII), and still maintain good performance at high temperature. Further thermal analysis showed that C₆₀-DBTMP interact with the decomposition products during the thermal decomposition of nitrocellulose, which changed the decomposition mechanism of nitrocellulose at the initial stage of thermal decomposition from self-accelerating catalytic model to non-autocatalytic reaction model. The stabilization mechanism was also investigated in detail, electron spin resonance (ESR) test showed that the nitroxide radicals scavenging efficiency of C₆₀-DBTMP is 73.4%, and effectively inhibit the acidity change caused by the thermal decomposition of nitrocellulose. Our study demonstrated the potential application of this multifunctional fullerene derivative as a stabilizer for propellants and provided a new strategy for designing high-performance stabilizers.

Improvement of immunodetection of the transcription factor C/EBP homologous protein by western blot

Accumulation of misfolded proteins within the endoplasmic reticulum (ER) induces an unfolded protein response (UPR) that either restores homeostasis or triggers apoptosis in case of adaptation failure. The three activated branches of UPR lead to IRE1-, PERK- and ATF6- dependent transcriptional induction of the gene encoding the transcription factor C/EBP homologous protein (CHOP) which plays an important role in apoptosis induction. In conventional immunoblotting conditions, detection of CHOP is a difficult task. Using a fixation step, we have optimized the detection of CHOP and this method provides a valuable tool to decipher CHOP involvement in UPR.

Experimental and theoretical study on thermal kinetics and reactive mechanism of nitrocellulose pyrolysis by traditional multi kinetics and modeling reconstruction

Nitrocellulose (NC) has been applied in many fields of daily life and military industry, but its instability brings large danger during storage and usage, which greatly limits its application. In this study, decomposition behavior and reaction model of NC were explored. To obtain its kinetic triplets during decomposition, NC samples were heated in nitrogen atmosphere with different heating rates of 5, 10, 15, 20 °C min^-1, respectively. A 3-th order reaction model was obtained by model fitting methods. Meanwhile, the relationship between activation energy and conversion was obtained by multi isoconversional methods, including KAS, FR, FWO, and Advanced Vyazovkin methods. Then the reaction model was reconstructed by introducing adjustment functions with result of an expression of f(α) = 19.38193α^1.41177(1-α)^4.60503.

Solid-phase nuclear magnetic resonance immunoassay for the prostate-specific antigen by using protein-coated magnetic nanoparticles

A solid phase NMR-based sandwich immunoassay for the prostate-specific antigen (PSA) is presented. Carbon-encapsulated iron nanoparticles were functionalized with bovine serum albumin, coupled to monoclonal antibodies, and then used as magnetic labels. A nitrocellulose membrane with 8-μm pores was coated with capture antibodies and subsequently incubated with a serum sample and a suspension of the nanoconjugate. Test strips were placed in a portable homemade NMR relaxometer. Magnetic nanoparticles attached to nitrocellulose decrease the T2 relaxation time of the water protons located inside the pores of the membrane. Thus, T2 is inversely proportional to the concentration of the antigen (PSA) in the sample. The assay can be performed within 4 h. The detection limit is 0.44 ng mL^-1. Kallikrein 2, human chorionic gonadotropin, and α-fetoprotein do not interfere. Graphical abstractSchematic representation of NMR relaxometry-based sandwich dot blot immunoassay of a prostate-specific antigen (PSA). Magnetic nanoparticles bound to immunosorbent decrease the transverse relaxation times (T2) of the water protons located within the pores of the membrane. RF coil: radiofrequency coil.

"Raincoat for explosives": Surface chemistry approach to control wetting of nitrocellulose with nitroglycerin

HYPOTHESIS

Wicking and percolation of a liquid in porous media is, among other factors, strongly affected by wettability of the pores. Nitrocellulose (NC) fibrous matrix impregnated with nitroglycerin (NG) is a main component of propellant formulations. Over time, NG, being a wetting liquid, leaks out from the matrix causing fires and explosions resulting from the storage. Here, we propose a chemical functionalization approach aimed at preparation of lyophobic coatings of NC to control wetting and to inhibit leakage of NG.

EXPERIMENTAL

NC was functionalized by a two-step process using the reaction of 3-(triethoxysilyl-propyl) isocyanate followed by reactions with either alkyl-, fluoroalkyl-, or phenyl-silane producing NC surfaces ranging in lyophobicity. The wettability of the NC pellets was characterized using water, hexadecane, and NG as probe fluids.

FINDINGS

FTIR and chemical analysis supported the covalent attachment of organosilanes to NC via robust carbamate and siloxane bonds. SEM and DSC of the modified NC materials suggested that the bulk properties of NC were not affected by the reactions with silanes. The contact angles of the modified NC changed over a wide range demonstrating surfaces with "tunable" wetting. NC grafted with fluoroalkyl-groups showed the most NG-repelling properties (θ_Adv/θ_Rec ∼ 90°/50°): NG beaded up and did not penetrate these surfaces.

Reaction yield model of nitrocellulose alkaline hydrolysis

Military nitrocellulose waste is flammable and explosive, and thus requires safe disposal and resource utilization. The alkaline hydrolysis process is a potential treatment method for nitrocellulose waste. In this study, a reaction yield model of nitrocellulose alkaline hydrolysis reaction was studied. For this purpose, a theoretical reaction yield model of nitrocellulose alkaline hydrolysis was developed based on Fick's law and scanning electron microscopy analysis. Additionally, the reaction yield model was experimentally validated. The results revealed a linear relationship between the nitrocellulose alkaline hydrolysis rate of x_NC and the reaction time of t, which is given by t/t_f = x_NC. The limiting step of the alkaline hydrolysis of nitrocellulose is the rate of diffusion of OH^- through the large pore channels. Accordingly, the reaction rate of the nitrocellulose alkaline hydrolysis can be increased by increasing the KOH concentration, reaction temperature, and reducing the size of the nitrocellulose granules. Thus, this model provides theoretical and technical support for the safe disposal and resource utilization of nitrocellulose waste.

Analysis of Nanomaterial Toxicity by Western Blot

Western blot is a routine biochemical technique for the immunodetection of proteins in cells and tissues exposed to nanomaterials (NMs). It is a sensitive method for protein analysis that involves the solubilization and separation of proteins by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), transferring and immobilizing proteins onto a solid support, and targeted immunoprobing of a specific antigen. As a convenient and reliable research tool, the western blot plays an irreplaceable role in the era of proteomics together with mass spectrometry and protein chip. In this chapter we describe the detailed protocol for the entire process from sample preparation to quantitative measurement of target proteins.

Electrospin-coating of nitrocellulose membrane enhances sensitivity in nucleic acid-based lateral flow assay

Point-of-care biosensors are important tools developed to aid medical diagnosis and testing, food safety and environmental monitoring. Paper-based biosensors, especially nucleic acid-based lateral flow assays (LFA), are affordable, simple to produce and easy to use in remote settings. However, the sensitivity of such assays to infectious diseases has always been a restrictive challenge. Here, we have successfully electrospun polycaprolactone (PCL) on nitrocellulose (NC) membrane to form a hydrophobic coating to reduce the flow rate and increase the interaction rate between the targets and gold nanoparticles-detecting probes conjugates, resulting in the binding of more complexes to the capture probes. With this approach, the sensitivity of the PCL electrospin-coated test strip has been increased by approximately ten-fold as compared to the unmodified test strip. As a proof of concept, this approach holds great potential for sensitive detection of targets at point-of-care testing.

Sorption and desorption kinetics of nitroglycerin and 2,4-dinitrotoluene in nitrocellulose and implications for residue-bound energetic materials

Energetic materials (EMs) bound to propellant residues can contribute to environmental risk and public health concerns. This work investigated how nitrocellulose, a common binding material in propellants, may control the release dynamics of nitroglycerin (NG) and 2,4-dinitrotoluene (2,4-DNT) from propellant residues. Batch adsorption/desorption experiments on nitrocellulose and re-interpretation on results from past leaching studies involving propellant-bound EMs were conducted. Mechanistic modeling of adsorption/desorption kinetics based on intra-particle diffusion (IPD) predicted aqueous intrinsic diffusivities (D_iw) to within a factor of 2 of expected values. Furthermore, the IPD model was able to predict effective diffusivities (D_eff) during the early leaching of NG from propellant residues to within a factor of 2 over a 3-log unit range. Prediction of leaching D_eff's associated with fired residues was less successful probably due to the neglect of compositional and morphological heterogeneity within the residues. Close correlations were found between the early and late D_eff's of residue-bound NG and between the fast- and slow-domain rate constants for both EMs, suggesting that the late leaching kinetics of bound-EMs may be empirically assessed from the early kinetics. This work illustrates that, in addition to dissolution, retarded diffusion through nitrocellulose matrix may also limit the overall release and transformation of residue-bound EMs in the field. Implications and limitations of the current study, and the steps forward are also presented.

Leaching of propellant compounds from munition residues may be controlled by sorption to nitrocellulose

Sustainable management of military ranges requires effective assessment of surface mobility and leaching potential of propellant compounds (PCs). Previous studies have focused mostly on PCs' dissolution from fired residues and their sorption to soil components. This work investigated the potential role of nitrocellulose, a major component in propellants, in the binding of PCs to propellant residues. Sorption isotherms of military grade nitrocellulose for dissolved nitroglycerine (NG) or 2,4-dinitrotoluene (2,4-DNT) was measured in batch experiments and were determined to be S_NG=10^2.39(±0.05)C_NG^{0.916(±0.032)} and S_2,4-DNT=10^3.08(±0.01)C_2,4-DNT^{0.668(±0.010)} (S and C in mg/kg_{nitrocellulose} and mg/L_wat, respectively). Solid-to-water partitioning for NG and 2,4-DNT was 100 times greater in propellant residues than in typical military ranges soils. Since nitrocellulose can sorb NG and 2,4-DNT up to 23 and 5% of its mass, respectively, it can slow down, through retarded diffusion, the leaching of PCs from fired residues over the typical composition ranges of common propellants. The slow leaching of PCs from propellant grains in column studies can be better interpreted by considering their sorptive interaction with nitrocellulose in addition to dissolution kinetics. With nitrocellulose as the carrying matrix, residue-bound PCs may migrate farther and persist longer in subsurface environment.

Experimental study on the thermal decomposition and combustion characteristics of nitrocellulose with different alcohol humectants

Although the thermal behaviors including thermal instability of nitrocellulose (NC) and its mixtures with some humectants have been comprehensively examined previously in the literature, their combustion characteristics have not been systematically studied. To address the issue, the combustion properties of NC with alcohol humectants are investigated by the means of the ISO 5660 cone calorimeter. Two kinds of NC-humectant mixtures with 30wt.% isopropanol and 30wt.% ethanol, respectively, were employed as samples. The tests were conducted under different external radiations, ranging from 0-15kW/m². The experimental results indicate that the external radiation positively influences the peak heat release rate (HRR) intensity and the maximum mass loss rate (MLR), while the total heat release (THR) decreases with the elevated external radiation. Comparatively, the sample with isopropanol exhibits a higher fire risk, characterized by the higher peak HRR, THR and maximum MLR. Auxiliary investigating methods, including Scanning Electron Microscopy and Differential Scanning Calorimeter-Thermal Gravimetric Analysis, were applied to examine the micro structure and thermal behavior of NC-humectant mixtures. The results helped to explain the burning characteristics observed in the cone calorimeter tests.

Gold nanocage-based lateral flow immunoassay for immunoglobulin G

The authors describe a gold nanocage-based lateral flow strip biosensor (LFSB) for low-cost and sensitive detection of IgG. This protein was used as a model analyte to demonstrate the proof-of-concept. The method combines the unique optical properties of gold nanocages (GNCs) with highly efficient chromatographic separation. A sandwich-type of immunoreactions occurs on the GNC-based LFSB which has the attractive features of avoiding multiple incubation, separation, and washing steps. The captured GNCs on the purple test zone and control zone of the biosensor are producing characteristic purple bands, and this enables IgG even to be visually detected. Quantitatation was accomplished by reading the intensities of the bands with a portable strip reader. The LFSB fabrication and assay parameters were optimized. The biosensor displays a linear response in the 0.5 to 50 ng·mL^-1 IgG concentration range, and it has a 15 min assay time. The detection limit is 0.1 ng·mL^-1 of IgG, which is 2.5 times lower than that when using a gold nanoparticle-based LFSB. In our perception, this assay has a wide potential for the detection of other proteins and species for which respective antibodies are available.

Validating Antibody Specificities for Immunohistochemistry by Protein Blotting Methods

Immunoblotting has been used in conjunction with other important antibody based detection methods like enzyme linked immunosorbent assay and immunohistochemistry to provide confirmation of results both in research and diagnostic testing. Specificity of antibodies employed for immunohistochemical studies is of critical importance and therefore the use of western blotting is imperative to address specificity of antibodies. In spite of its overall simplicity, western blotting or protein blotting is a powerful procedure for immunodetection of proteins, especially those that are of low abundance, following electrophoretic separation. The usefulness of this procedure stems from its ability to provide simultaneous resolution of multiple immunogenic antigens within a sample for detection by specific antibodies. Protein blotting has evolved greatly over the last few decades and researchers have a variety of ways and means to carry out this procedure to validate antibodies for immunohistochemistry.

Correlating molar masses of nitrocelluloses with their intrinsic viscosities measured using capillary electrophoresis instrumentation

Specific viscosities for a set of six nitrocellulose (NC) standards comprising three different mass-average molar masses (between 20,000 and 300,000 g mol(-1)) of two different nitrogen contents (11.2 and 12.1%) were measured at 20 °C in tetrahydrofuran, using capillary electrophoresis instrumentation as a bench-top viscometer in frontal mode. Intrinsic viscosities were derived applying Huggins' and Kraemer's models, showing excellent convergence of both models at infinitely diluted polymer concentration. Good overall consistency was shown between viscosity data experimentally acquired by this new protocol and the mass-average molar masses provided by the manufacturers. This simple protocol should be of interest for a better understanding of the solvent interaction given by this complex polymer, and beyond this, for tailoring NC solutions devoted to film deposition, and for the determination of mass-average molar masses of unknown NC samples.

A new method for the determination of the nitrogen content of nitrocellulose based on the molar ratio of nitrite-to-nitrate ions released after alkaline hydrolysis

A new method was proposed to determine the nitrogen content of nitrocelluloses (NCs). It is based on the finding of a linear relationship between the nitrogen content and the molar ratio of nitrite-to-nitrate ions released after alkaline hydrolysis. Capillary electrophoresis was used to monitor the concentration of nitrite and nitrate ions. The influences of hydrolysis time and molar mass of NC on the molar ratio of nitrite-to-nitrate ions were investigated, and new insights into the understanding of the alkaline denitration mechanism of NCs, underlying this analytical strategy is provided. The method was then tested successfully with various explosive and non-explosive NC-containing samples such as various daily products and smokeless gunpowders. Inherently to its principle exploiting a concentration ratio, this method shows very good repeatability in the determination of nitrogen content in real samples with relative standard deviation (n = 3) inferior to 1.5%, and also provides very significant advantages with respect to sample extraction, analysis time (1h for alkaline hydrolysis, 3 min for electrophoretic separation), which was about 5 times shorter than for the classical Devarda's method, currently used in industry, and safety conditions (no need for preliminary drying NC samples, mild hydrolysis conditions with 1M sodium hydroxide for 1h at 60 °C).

Flow-through, viral co-infection assay for resource-limited settings

Here we present a new and rapid immunofiltration assay for simultaneous detection of HIV p24 and hepatitis B virus antigens. The assay platform is composed of a 13 mm nitrocellulose filter spotted with capturing bioprobes and inserted in a Swinnex(®) syringe filter holder. Samples and reagents are flown through the nitrocellulose filter by manual pressure on the syringe. A colorimetric detection allows for naked eye results interpretation. The assay provides sensitivity in the picomolar range in just 5 min, even using low volumes of sample in complex matrix. Probe deposition by spotting allows for flexible combinations of different capturing agents and multiple diagnoses; furthermore, the very simple and inexpensive set-up makes the syringe-based immunoassay on paper microarray a suitable diagnostic system for resource-limited settings.

Electron beam lithography with feedback using in situ self-developed resist

Due to the lack of feedback, conventional electron beam lithography (EBL) is a 'blind' open-loop process where the exposed pattern is examined only after ex situ resist development, which is too late for any improvement. Here, we report that self-developing nitrocellulose resist, for which the pattern shows up right after exposure without ex situ development, can be used as in situ feedback on the e-beam distortion and enlargement. We first exposed identical test pattern in nitrocellulose at different locations within the writing field; then, we examined in situ at high magnification the exposed patterns and adjusted the beam (notably working distance) accordingly. The process was repeated until we achieved a relatively uniform shape/size distribution of the exposed pattern across the entire writing field. Once the beam was optimized using nitrocellulose resist, under the same optimal condition, we exposed the common resist PMMA. We achieved approximately 80-nm resolution across the entire writing field of 1 mm × 1 mm, as compared to 210 nm without the beam optimization process.

Stain-Free total protein staining is a superior loading control to β-actin for Western blots

Semi-quantification of proteins using Western blots typically involves normalization against housekeeping genes such as β-actin. More recently, Ponceau S and Coomassie blue staining have both been shown to be suitable alternatives to housekeeping genes as loading controls. Stain-Free total protein staining offers the advantage of no staining or destaining steps. Evaluation of the use of Stain-Free staining as an alternative to β-actin or the protein stain Ponceau S showed that Stain-Free staining was superior to β-actin and as good as or better than Ponceau S staining as a loading control for Western blots.