Increasing surface capacity for on-probe affinity capture MALDI-MS via gold particle attachment to allyl amine plasma polymers

In this study, we demonstrate that the protein binding capacity of a surface modified matrix-assisted laser desorption/ionization (MALDI) target can be increased significantly by architecturing the surface of the MALDI probe using gold microparticles. In the present approach, a MALDI target, initially modified via pulsed rf plasma deposition of an allyl amine polymer thin film, is subsequently architectured via reaction with 2-iminothiolane and surface attachment of gold microparticles. The modified probe is then exposed to thiolated biotin to introduce an avidin binding element on the surface of the gold beads. The protein binding capacity of this architectured target is compared with a similarly plasma polymer modified MALDI target that is directly biotinylated. Application of various surface concentrations of avidin to the two probes and MALDI-MS analysis of avidin contained in the solution removed from the probe reveals that saturation of the gold-particle architectured target occurs at a factor of 15-30 higher applied surface concentration, as compared with the unarchitectured target. Furthermore, MALDI-MS analysis of the avidin retained on the two probes reveals that the limit of detection is lowered by a factor of 15-20 on the gold-particle architectured target as compared with the unarchitectured target.     

Mixed monolayer-protected gold nanoclusters as selective peptide extraction agents for MALDI-MS analysis

Cationic and anionic nanoparticles selectively target peptides with low and high isoelectric points, respectively. Additionally, their high surface area-to-volume ratios make these nanoparticles (approximately 2-nm core diameter) very efficient extraction and concentration agents. Upon extraction, the peptide-bound nanoparticles can be analyzed by MALDI-MS to provide highly sensitive detection of the targeted peptides. We demonstrate that MALDI-MS can detect peptide concentrations as low as 500 pM from 250-microL solutions using these nanoparticle scaffolds as extraction and concentration agents.     

High sensitivity DNA detection based on regioselectively decorated electrocatalytic nanoparticles

Self-assembled monolayers (SAMs) of dodecanethiol have been formed on gold electrodes to produce nanoscale defects. These defects define nucleation sites for the electrodeposition of mushroom shaped platinum nanoparticles (PtNPs). The top surfaces of these PtNPs have been selectively functionalized with single stranded probe DNA. These regioselectively modified particles were desorbed by applying a current jump to yield nanoparticles capable of biorecognition on the top curved side and efficient electrocatalysis on the nonfunctionalized lower surface. A second electrode was functionalized with single stranded capture DNA that has a sequence that is complementary to the pathogen, Staphylococcus aureus but leaves a section of the target available to bind the probe strand immobilized on the PtNPs. Following hybridization of the target and capture strands, the surface was exposed to the probe DNA labeled electrocatalytic PtNPs. Target binding was detected by monitoring the current associated with the reduction of hydrogen peroxide in a solution of 0.01 M H(2)SO(4). Calibration plots of the log[DNA] versus faradaic current were linear from 10 pM to 1 μM and picomolar concentrations could be detected without the need for amplification of the target, for example, using PCR or NASBA. As well as a wide dynamic range, this detection strategy has an excellent ability to discriminate DNA mismatches and a high analytical sensitivity.     

Use of polymer-modified MALDI-MS probes to improve analyses of protein digests and DNA

The use of sample probe surfaces patterned with 200-microm-diameter spots of hydrophilic, charged polymers significantly enhances the analysis of protein digests and DNA by MALDI-MS. Selective adsorption on these polymer-modified surfaces allows collection of specific proteolytic peptides, while subsequent rinsing of the deposited sample removes contaminants. In the case of partially digested myoglobin, the mass spectrum obtained using a sample probe modified with polyanionic functionalities permits detection of 22 proteolytic fragments, while analysis using a stainless steel MALDI sample probe gives only 11 detectable fragments. Similarly, during the analysis of bovine serum albumin digests, the use of several different surface-modified MALDI sample probes increases sequence coverage from 61.3 to 74.5%. Detection of phosphorylated peptides can be quite challenging during analyses of phosphoprotein digests by MALDI-MS because these anionic proteolytic fragments have low ionization efficiencies. However, MALDI signals from the phosphorylated proteolytic fragments sometimes increase dramatically when using a sample probe surface modified by a polycation (polyethylenimine or poly(acrylic acid) complexed with Fe(3+)). The signal enhancement apparently occurs because the positive surface selectively binds the phosphorylated peptides. The use of patterned, polycationic surfaces also shows great promise for selective adsorption and decontamination of DNA samples; a simple water rinse diminishes or eliminates the formation of multi-ion adducts, thereby improving mass resolution during subsequent analysis by MALDI-MS.     

Porphyrin Monolayer‐Modified Gold Clusters as Photoactive Materials

Porphyrin monolayer‐modified gold clusters (three‐dimensional system) have been prepared successfully. Their electrochemical and photophysical properties have been compared to those of the corresponding two‐dimensional system of self‐assembled monolayers (SAMs) of the porphyrin as well as the bis(porphyrin) disulfide reference in solutions. In particular, the time‐resolved single‐photon counting fluorescence studies have indicated that the undesirable quenching of the porphyrin excited singlet state via energy transfer to the gold surface of the three‐dimensional system is much suppressed, as compared to the quenching of the porphyrin SAMs on the two‐dimensional flat gold surface. Thus, the present systems have a variety of potential utility for development of the artificial photosynthetic materials, photocatalysts, and chemical and biochemical sensors using fluorescent chromophore‐monolayer modified gold clusters.     

An automated noncontact deposition interface for liquid chromatography matrix-assisted laser desorption/ionization mass spectrometry

A new multichannel deposition system was developed for off-line liquid chromatography/matrix-assisted laser desorption/ionization mass spectrometry (LC/MALDI-MS). This system employs a pulsed electric field to transfer the eluents from multiple parallel columns directly onto MALDI targets without the column outlets touching the target surface. The deposition device performs well with a wide variety of solvents that have different viscosities, vapor pressures, polarities, and ionic strengths. Surface-modified targets were used to facilitate concentration and precise positioning of samples, allowing for efficient automation of high-throughput MALDI analysis. The operational properties of this system allow the user to prepare samples using MALDI matrixes whose properties range from hydrophilic to hydrophobic. The latter, exemplified by alpha-cyano-4-hydroxycinnamic acid, were typically processed with a multistep deposition method consisting of precoating of individual spots on the target plate, sample deposition, and sample recrystallization steps. Using this method, 50 amol of angiotensin II was detected reproducibly with high signal-to-noise ratio after LC separation. Experimental results show that there is no significant decrease in chromatographic resolution using this device. To assess the behavior of the apparatus for complex mixtures, 5 microg of a tryptic digest of the cytosolic proteins of yeast was analyzed by LC/MALDI-MS and more than 13,500 unique analytes were detected in a single LC/MS analysis.     

Assessment of pilot-scale acid washing of soil contaminated with As, Zn and Ni using the BCR three-step sequential extraction

This study performed pilot-scale washing of soil contaminated with both oxyanion and cations as a recalcitrant remediation case due to their different chemical behavior. The soil contaminated with As, Zn and Ni, partially recalcitrant due to their strong binding properties, was obtained near a closed iron/serpentine mining area. This study monitored the variation of chemical speciation of As, Zn and Ni for acid solutions and particle size fraction using the BCR sequential extraction and evaluated the optimal condition of physical separation of highly contaminated fine particles for enhanced washing. H(2)SO(4) and H(3)PO(4), including competitive oxyanions, enhanced removal of As with the simultaneous extraction of Zn and Ni. Less nickel from the residual fraction in coarse particles was extracted than As and Zn due to the recalcitrant serpentine. Fe/Mn oxide, organic/sulfides and residual fractions in fine particles were enriched with contaminants due to the high surface areas and recalcitrant minerals. The chemical extraction of As was also restricted in the fine particles, whereas the chemical extraction of Zn and Ni was determined by the residual form of various particle size fractions. Further extraction was limited in the exchangeable and residual fractions and retained a gradual extraction from Fe/Mn oxide and organic/sulfides fractions, which indicated an instant detachment from the easily bound fraction. Correspondingly, extraction from the acid-attackable fraction was related to the exchangeable Fe/Mn oxide and organic/sulfides fractions. Due to the limitation of chemical extraction, the physical separation of fine particles could enhance the effectiveness of acid washing. In addition, the chemical properties of the soil were affected by strong acid washing. The treated soil then needed to be regenerated.     

Effects of chemical competition for multi-metal binding by Medicago sativa (alfalfa).

Alfalfa shoot biomass has demonstrated the ability to bind an appreciable amount of cadmium(II), chromium(III), copper(II), lead(II), nickel(II), and zinc(II) separately from aqueous solutions. Since most heavy metal contaminated waters contain more than one heavy metal ion, it was necessary to determine the binding abilities of the alfalfa biomass with multi-metal solutions. Batch laboratory experiments were performed with a solution containing 0.1 mM of each of the following metal ions: cadmium(II), chromium(III), copper(II), lead(II), nickel(II), and zinc(II). We determined the pH profile, time dependency, and binding capacity by the alfalfa biomass of each metal ion under multi-elemental conditions. For all the metal ions studied, the alfalfa biomass showed to have a high affinity for metal binding around pH 5.0 within a time period of approximately 5 min. The binding capacity experiments showed that there was a preferential binding of the metal ions from the multi-elemental solution with the following amounts of metal ion bound per gram of biomass: 368.5 micromol/g for copper(II), 215.4 micromol/g for chromium(III), 168.0 micromol/g for lead(II), 56.9 micromol/g for zinc(II), 49.2 micromol/g for nickel(II), and 40.3 micromol/g for cadmium(II). Reacting the biomass from the capacity experiments with 0.1 M HCl resulted in 90% or greater recovery of bound cadmium, copper, lead, nickel, and zinc. However, only 44% of the bound chromium was recovered. These experiments show the ability of Medicago sativa (alfalfa) to bind several metal ions under multi-contaminant conditions. Similar results were obtained when the experiments were performed under flow conditions using silica-immobilized alfalfa biomass. Chromium bound on the silica-immobilized biomass was also difficult to be desorbed with 0. 1 M HCl. The information obtained will be useful for the future development of an innovative technology to remove heavy metal contaminants from polluted ground waters.     

Affinity capture using vancomycin-bound magnetic nanoparticles for the MALDI-MS analysis of bacteria

Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) provides a straightforward means to differentiate microorganism species based on mass spectral fingerprinting. The pathogen cell concentration in an infected sample, however, is generally lower than that capable of being detected directly by MALDI-MS. Furthermore, the presence of proteins or metabolites in biological fluids always causes unavoidable interference for the identification of microorganism species. Vancomycin, which binds to D-Ala-D-Ala moieties on the cell walls of Gram-positive bacteria and, therefore, inhibits peptidoglycan synthesis, is one of the most potent antibiotics. Thus, we have employed vancomycin-modified magnetic nanoparticles as affinity probes to selectively trap Gram-positive pathogens from sample solutions; i.e., these bacteria can be isolated from sample solutions by applying a magnetic field. The isolated cells could then be characterized by MALDI-MS. This approach effectively reduces the interference of protein and metabolite signals in the mass spectra of Gram-positive bacteria because vancomycin has such high specificity for the D-Ala-D-Ala units of the cell walls. The lowest cell concentration we detected for both Staphylococcus saprophyticus and Staphylococcus aureus in a urine sample (3 mL) was approximately 7 x 10(4) cfu/mL.     

Coupling of protein HPLC to MALDI-TOF MS using an on-target device for fraction collection, concentration, digestion, desalting, and matrix/analyte cocrystallization

Multidimensional protein chromatography offers an alternative to gel-based separations for large-scale proteomic analyses of highly complex mixtures. However, these liquid separations divide the original mixtures into multitudes of discrete samples, each of which may require numerous steps of sample manipulation, such as fraction collection, buffer exchange, protease digestion, peptide desalting, and, in the case of MALDI-MS, matrix and analyte cocrystallization on target. When traditional high-flow liquid chromatography is used, large volumes of solvent must also be removed from fractions to maximize MS sensitivity. Although robotic liquid-handling devices can facilitate these steps and reduce analyst/sample contact, they remain prototypic and expensive. Here, we explore the use of a novel, one-piece elastomeric device, the BD MALDI sample concentrator, which affixes to a MALDI target to create a prestructured 96-well sample array on the target surface. We have developed methodologies to process high-flow HPLC fractions by collecting them directly into the elastomeric device and then subjecting them to sequential on-target sample concentration, buffer exchange, digestion, desalting, and matrix/analyte cocrystallization for MALDI-MS analyses. We demonstrate that this methodology enables the rapid digestion and analysis of low amounts of proteins and that it is effective in the characterization of an HPLC-fractionated protein mixture by MALDI-TOF MS followed by peptide mass fingerprinting.     

Effect of different extraction agents on metal and organic contaminant removal from a field soil

This paper presents an evaluation of different extracting solutions for the removal of phenanthrene, lead and zinc from a contaminated soil obtained from a former manufactured gas plant site. The field soil contained 50%-88% sand, 11%-35% fines, 2.7%-3.7% organic matter and high concentrations of phenanthrene (260 mg/kg), lead (50.6 mg/kg) and zinc (84.4 mg/kg). A series of batch extraction experiments were conducted using the field soil with different extracting solutions at various concentrations to investigate the removal efficiency and to optimize the concentration of each extractant. The results showed that removal efficiencies of different flushing systems were significantly influenced by their affinity and selectivity for the contaminants in the soil matrix. Non-ionic surfactants (Igepal CA720 and Tween 80) were found to be effective in removing phenanthrene, but they were ineffective in removing lead and zinc. Chelating agents (ethylenediamine tetra acetic acid, EDTA and diethylene triamine penta acetic acid, DTPA) and selected acids were effective in removing lead and zinc, but they were ineffective for the phenanthrene removal. Co-solvents and cyclodextrins were not effective for removal of any of the contaminants. A sequential use of the 0.2 M EDTA followed by 5% Tween 80 or 5% Tween 80 followed by 1 M citric acid was found to be effective for the removal of lead, zinc, and phenanthrene. Overall, it can be concluded that sequential use of different extracting solutions is required for the removal of both heavy metals and organics from field contaminated silty sand soils.     

Device for the reversed-phase separation and on-target deposition of peptides incorporating a hydrophobic sample barrier for matrix-assisted laser desorption/ionization mass spectrometry

The separation of peptide mixtures from proteolytic cleavage is often necessary prior to mass spectrometry (MS) to enhance sensitivity and peptide mapping coverage. When buffers, salts, and other higher abundance peptides/contaminants are present, competition for charge during the electrospray ionization and matrix-assisted laser desorption/ionization (MALDI) processes can lead to ion suppression for the targeted analyte(s). In this note, a simple reversed-phase microcolumn sample separation and deposition device (Sep-Dep) is described. The use of this device improves or renders possible the analysis of complex or contaminated peptide mixtures by MALDI-MS. The method is simple and inexpensive and utilizes single-use low-cost Geloader-type columns packed with reversed-phase material. The device described utilizes an open column, allowing for a gradient or narrow-step gradient to be applied by any solvent delivery system or manually with a pipet. A key feature of the device is a deposition chamber that can be custom-built to hold any MALDI target. The Sep-Dep device is attached directly to an in-house vacuum line and draws solvent from the open-ended LC column. The elution of separated peptides is performed directly onto a target that has been treated with a hydrophobic barrier. This barrier effectively isolates fractions and improves the quality and morphology of the matrix crystals. The method produces efficient separations of proteolytic peptides, significantly reducing signal suppression effects in MALDI.     

Passive standoff detection of chemical warfare agents on surfaces

Results are presented on the passive standoff detection and identification of chemical warfare (CW) liquid agents on surfaces by the Fourier-transform IR radiometry. This study was performed during surface contamination trials at Defence Research and Development Canada-Suffield in September 2002. The goal was to verify that passive long-wave IR spectrometric sensors can potentially remotely detect surfaces contaminated with CW agents. The passive sensor, the Compact Atmospheric Sounding Interferometer, was used in the trial to obtain laboratory and field measurements of CW liquid agents, HD and VX. The agents were applied to high-reflectivity surfaces of aluminum, low-reflectivity surfaces of Mylar, and several other materials including an armored personnel carrier. The field measurements were obtained at a standoff distance of 60 m from the target surfaces. Results indicate that liquid contaminant agents deposited on high-reflectivity surfaces can be detected, identified, and possibly quantified with passive sensors. For low-reflectivity surfaces the presence of the contaminants can usually be detected; however, their identification based on simple correlations with the absorption spectrum of the pure contaminant is not possible.     

Construction of multilayers of bare and Pd modified gold nanoclusters and their electrocatalytic properties for oxygen reduction

Abstract

Multilayers of gold nanoclusters (GNCs) coated with a thin Pd layer were constructed using GNCs modified with self-assembled monolayers (SAMs) of mercaptoundecanoic acid and a polyallylamine hydrochloride (PAH) multilayer assembly, which has been reported to act as a three-dimensional electrode. SAMs were removed from GNCs by electrochemical anodic decomposition and then a small amount of Pd was electrochemically deposited on the GNCs. The kinetics of the oxygen reduction reaction (ORR) on the Pd modified GNC/PAH multilayer assembly was studied using a rotating disk electrode, and a significant increase in the ORR rate was observed after Pd deposition. Electrocatalytic activities in alkaline and acidic solutions were compared both for the GNC multilayer electrode and Pd modified GNC electrode.     

Characterization of trypsin immobilized on the functionable alkylthiolate self-assembled monolayers: A preliminary application for trypsin digestion chip on protein identification using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

Self-assembled monolayers (SAMs) on coinage metal provide versatile modeling systems for studies of interfacial electron transfer, biological interactions, molecular recognition and other interfacial phenomena. Recently the bonding of enzyme to SAMs of alkanethiols onto Au electrode surfaces was exploited to produce a bio-sensing system. In this work, the attachment of trypsin to a SAMs surface of 11-mercaptoundecanoic acid was achieved using water soluble N-ethyl-N -(3-dimethylaminopropyl)carbodiimide hydrochloride and N-hydroxysuccinimide as coupling agent. The thickness of SAMs was determined by optical ellipsometer; contact angles of the modified Au surfaces were measured in air using a goniometer. The Second Harmony Generation data displays the last few percents of the alkylthiol molecules adsorbed and produced the complete monolayer by inducing the transition from a high number of gauche defects to an all-trans conformation. Using X-ray Photoelectron Spectroscopy (XPS) and Fourier-Transformed Infrared Reflection-Absorption and Attenuated Total Reflection Spectroscopes (FTIR-RAS and ATR), we examined the chemical structures of samples with different treatments. By matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), we demonstrated the digestion of bovine serum albumin (BSA) on the trypsin-immobilized SAMs surface.Experimental results have revealed that the XPS C1s core levels at 286.3 and 286.5 eV (Amine bond), 288.1 eV (Amide bond) and 289.3 eV (Carboxylic acid) illustrate the immobilization of trypsin. These data were also in good agreement with FTIR-ATR spectra for the peaks valued at 1659.4 cm^{– 1} (Amide I) and 1546.6 cm^{– 1} (Amide II). Using MALDI-TOF MS observations, analytical results have demonstrated the BSA digestion of the immobilized trypsin on the functionalized SAMs surface. For such surfaces, BSA was digested on the trypsin-immobilized SAMs surface, which shows the enzyme digestion ability of the immobilized trypsin. The terminal groups of the SAMs structure can be further functionalized with biomolecules or antibodies to develop surface-base diagnostics, biosensors, or biomaterials.     

Gold nanoparticles as selective and concentrating probes for samples in MALDI MS analysis

MALDI mass spectrometry is used widely in various fields because it has the characteristics of speed, ease of use, high sensitivity, and wide detectable mass range, but suppression effects between analyte molecules and interference from the sample matrix frequently arise during MALDI analysis. The suppression effects can be avoided if target species are isolated from complicated matrix solutions in advance. Herein, we proposed a novel method for achieving such a goal. We describe a strategy that uses gold nanoparticles to capture charged species from a sample solution. Generally, ionic agents, such as anionic or cationic stabilizers, encapsulate gold nanoparticles to prevent their aggregation in solution. These charged stabilizers at the surface of the gold particles are capable of attracting oppositely charged species from a sample solution through electrostatic interactions. We have employed this concept to develop nanoparticle-based probes that selectively trap and concentrate target species in sample solutions. Additionally, to readily isolate them from solution after attracting their target species, we used gold nanoparticles that are adhered to the surface of magnetic particles through S-Au bonding. A magnet can then be employed to isolate the Au@magnetic particles from the solution. The species trapped by the isolated particles were then characterized by MALDI MS after a simple washing. We demonstrate that Au@magnetic particles having negatively charged surfaces are suitable probes for selectively trapping positively charged proteins from aqueous solutions. In addition, we have employed Au@magnetic particle-based probes successfully to concentrate low amounts of peptide residues from the tryptic digest products of cytochrome c (10(-7) M).     

Molecular dynamics simulation of the enhancement of cobra cardiotoxin and E6 protein binding on mixed self-assembled monolayer molecules

Molecular dynamics simulations are performed on n-alkinethiol self-assembled monolayers (SAMs) and their mixture on a gold surface so that the orientations of the binding of cobra cardiotoxin and E6 protein molecules can be selected using the mixing ratio of CH3-terminated SAMs with different chain lengths. The simulations suggest that a SAM surface with different mixing ratios may provide a possible platform for aligning protein molecules with a desired orientation and for enhancing the binding energy of the protein on the designed surface.     

Surface modification of gamma-Fe2O3@SiO2 magnetic nanoparticles for the controlled interaction with biomolecules

Modifying the surface of magnetic nanoparticles (MNPs) to allow for controlled interaction with biomolecules enables their implementation in biomedical applications such as contrast agents for magnetic resonance imaging, labels in magnetic biosensing or media for magnetically assisted bioseparation. In this paper, self-assembly of trialkoxysilanes is used to chemically functionalize the surface of gamma-Fe2O3@SiO2 core-shell particles. First, the silane deposition procedure was optimized using infrared analysis in order to obtain maximum packing density of the silanes on the particles. The surface coverage was determined to be approximately 8 x 10(14) molecules/cm2. It was shown that the magnetic, crystalline, and morphological properties of the MNPs were not altered by deposition of a thin silane coating. The optimized procedure was transferred for the deposition of aldehyde and poly(ethylene glycol) (PEG) presenting silanes. The presence of both silanes on the particle surface was confirmed using XPS and FTIR. The interaction of proteins with silane-modified MNPs was monitored using a Bradford protein assay. Our results demonstrate that, by introducing aldehyde functions, the MNPs are capable of covalently binding human IgG while retaining their specific binding capacity. Maximum surface coverage occurs at 46 microg antibodies per mg particle, which corresponds to 35 antibodies bound to an average sized MNP (54 nm in diameter). The human IgG functionalized MNPs exhibit a high degree of specificity (approximately 90%) and retained a binding capacity of 32%. Using the same approach, streptavidin was coupled onto the MNPs and the biotin binding capacity was determined using biotinylated fluorescein. At maximum surface coverage, a biotin binding capacity of 1500 pmol/mg was obtained, corresponding to a streptavidin activity of 76%. On the other hand, by introducing PEG functions the non-specific adsorption of serum proteins could be significantly suppressed down to approximately 3 microg/mg. We conclude that self-assembly of silane films creates a generic platform for the controlled interactions of MNPs with biomolecules.     

Removal of patulin from aqueous solutions by propylthiol functionalized SBA-15

Propylthiol functionalized SBA-15 silica was investigated to detoxify aqueous solutions contaminated with the regulated mycotoxin patulin. Micelle templated silicas with a specific pore size were synthetically modified to possess propylthiol groups, a functional group known to form Michael reaction products with the conjugated double bond system of patulin. BET surface area analysis indicated the propylthiol functionalized SBA-15 possesses channels with the pore size of 5.4 nm and a surface area of 345 m(2)g(-1). Elemental analysis indicates the silicon/sulfur ratio to be 10:1, inferring one propylthiol substituent for every ten silica residues. The propylthiol modified SBA-15 was effective at significantly reducing high levels of patulin from aqueous solutions (pH 7.0) in batch sorption assays at room temperature. The material was less effective at lower pH; however heating low pH solutions and apple juice to 60 °C in the presence of propylthiol functionalized SBA-15 significantly reduced the levels of patulin in contaminated samples. Composite molecular models developed by semi-empirical PM3 and empirical force field methods support patulin permeation through the mesoporous channels of propylthiol functionalized SBA-15. Density functional study at the B3LYP/6-31G(d,p) level predicts the proposed patulin adducts formed by reaction with the thiol residues exhibit less electrophilic properties than patulin. It is demonstrated the use of propylthiol functionalized SBA-15 is a viable approach to reduce patulin levels in aqueous solutions, including contaminated apple juice.     

Sugarcane bagasse: a potential low-cost biosorbent for the removal of hazardous materials

The contamination of surface water sources by organic and inorganic pollutants is a major concern in rapidly industrializing countries, and the removal of these potentially hazardous contaminants from the aquatic environment using environmentally friendly technologies is therefore crucial. Biosorption, the passive binding of pollutants using dead biomass, can be achieved using various low-cost agro-industrial residues, which are a convenient substitute to the existing technologies for removing pollutants from aqueous solutions. This review deals with the implementation of sugarcane bagasse as a cost-effective natural biosorbent. We have extensively reviewed the status of research into sugarcane bagasse-based biosorbents in raw and modified forms and explore their efficacy in the removal of pollutants. For this purpose, we considered the bagasse modification processes, modifying agents, and the effects of different experimental variables (for example, biosorbent dosage, initial pollutant ion concentration, solution pH and temperature, contact time, and adsorbent particle size) on the adsorption process and potential. Moreover, we propose the following important goals for future research: (1) determine the adsorption potential of sugarcane bagasse at pilot and industrial scales, (2) demonstrate the efficacies of biosorption techniques for real effluents, and (3) conduct a molecular modeling study to elucidate sugarcane bagasse-associated adsorption mechanism(s).