Chemically modified carbon nanotubes as material enhanced laser desorption ionisation (MELDI) material in protein profiling

Advances in nanotechnology for improving the targeted delivery and activity of amphotericin B (2011-2023): a systematic review

Amphotericin B (AmB) is a broad-spectrum therapeutic and effective drug, but it has serious side effects of toxicity and solubility. Therefore, reducing its toxicity should be considered in therapeutic applications. Nanotechnology has paved the way to improve drug delivery systems and reduce toxicity. The present study, for the first time, comprehensively reviews the studies from 2011 to 2023 on reducing the in vitro toxicity of AmB. The findings showed that loading AmB with micellar structures, nanostructured lipid carriers, liposomes, emulsions, poly lactide-co-glycolide acid, chitosan, dendrimers, and other polymeric nanoparticles increases the biocompatibility and efficacy of the drug and significantly reduces toxicity. In addition, modified carbon nanoparticles (including graphene, carbon nanotubes, and carbon dots) with positively charged amine groups, PEI, and other components showed favorable drug delivery properties. Uncoated and coated magnetic nanoparticles and silver NPs-AmB composites had less cytotoxicity and more antifungal activity than free AmB. Citrate-reduced GNPs and lipoic acid-functionalized GNPs were also effective nanocarriers to reduce AmB cytotoxicity and improve anti-leishmania efficacy. In addition, zinc oxide-NPs and PEGylated zinc oxide-NPs showed favorable antifungal activity and negligible toxicity. According to a review study, carbon-based nanoparticles, metal nanoparticles, and especially polymer nanoparticles caused some reduction in the toxicity and improved solubility of AmB in water. Overall, considering the discussed nanocarriers, further research on the application of nanotechnology as a cost-effective candidate to improve the efficiency and reduce the cytotoxicity of AmB is recommended.

Engineering of nanomaterials for mass spectrometry analysis of biomolecules

Mass spectrometry (MS) based analysis has received intense attention in diverse biological fields. However, direct MS interrogation of target biomolecules in complex biological samples is still challenging, due to the extremely low abundance and poor ionization potency of target biological species. Innovations in nanomaterials create new auxiliary tools for deep and comprehensive MS characterization of biomolecules. More recently, growing research interest has been directed to the compositional and structural engineering of nanomaterials for enriching target biomolecules prior to MS analysis, enhancing the ionization efficiency in MS detection and designing biosensing nanoprobes in sensitive MS readout. In this review, we mainly focus on the recent advances in the engineering of nanomaterials towards their applications in sample pre-treatment, desorption/ionization matrices and ion signal amplification for MS profiling of biomolecules. This review will provide a toolbox of nanomaterials for researchers devoted to developing analytical methods and practical applications in the biological MS field.

Recent Developments in Solid-Phase Extraction for Near and Attenuated Total Reflection Infrared Spectroscopic Analysis

A review with more than 100 references on the principles and recent developments in the solid-phase extraction (SPE) prior and for in situ near and attenuated total reflection (ATR) infrared spectroscopic analysis is presented. New materials, chromatographic modalities, experimental setups and configurations are described. Their advantages for fast sample preparation for distinct classes of compounds containing different functional groups in order to enhance selectivity and sensitivity are discussed and compared. This is the first review highlighting both the fundamentals of SPE, near and ATR spectroscopy with a view to real sample applicability and routine analysis. Most of real sample analyses examples are found in environmental research, followed by food- and bioanalysis. In this contribution a comprehensive overview of the most potent SPE-NIR and SPE-ATR approaches is summarized and provided.

Alternative profiling platform based on MELDI and its applicability in clinical proteomics

The presence of numerous proteomics data and their results in literature reveal the importance and influence of proteins and peptides on human cell cycle. For instance, the proteomic profiling of biological samples, such as serum, plasma or cells, and their organelles, carried out by surface-enhanced laser desorption/ionization mass spectrometry, has led to the discovery of numerous key proteins involved in many biological disease processes. However, questions still remain regarding the reproducibility, bioinformatic artifacts and cross-validations of such experimental set-ups. The authors have developed a material-based approach, termed material-enhanced laser desorption/ionization mass spectrometry (MELDI-MS), to facilitate and improve the robustness of large-scale proteomic experiments. MELDI-MS includes a fully automated protein-profiling platform, from sample preparation and analysis to data processing involving state-of-the-art methods, which can be further improved. Multiplexed protein pattern analysis, based on material morphology, physical characteristics and chemical functionalities provides a multitude of protein patterns and allows prostate cancer samples to be distinguished from non-prostate cancer samples. Furthermore, MELDI-MS enables not only the analysis of protein signatures, but also the identification of potential discriminating peaks via capillary liquid chromatography mass spectrometry. The optimized MELDI approach offers a complete proteomics platform with improved sensitivity, selectivity and short sample preparation times.

New stationary phases for enrichment and separation in the 'omics' era

'Omics' is a general term for a broad discipline of science and engineering concerned with analyzing the interactions of biological molecular components in various 'omes'. These include genome, proteome, metabolome, expressome and interactome. 'Ome' and 'omics' are very convenient handles for describing the holistic approach for looking at complex systems. 'Omics' will not only have an impact on our understanding of biological processes, but also on the prospect of more accurately diagnosing and treating disease. The development of these 'omics' has depended on, and has also driven, advances in chromatography and electrophoresis, as well as highly sensitive and specific analytical techniques to permit the handling of large numbers of samples with high selectivity and sensitivity. The development and design of novel stationary phases for selective enrichment and separation is one of the key points for establishing a successfully running 'omics' platform. Therefore, this review demonstrates the application of different new materials developed in our laboratory, such as chromatographic stationary phases for selective and sensitive high-speed purification, enrichment and separation in genomics, proteomics and metabolomics.

Laser desorption/ionization mass spectrometric analysis of small molecules using fullerene-derivatized silica as energy-absorbing material

In spite of the growing acceptance of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry for the analysis of a wide variety of compounds, including polymers and proteins, its use in analyzing low-molecular-weight molecules (<1000 m/z) is still limited. This is mainly due to the interference of matrix molecules in the low-mass range. Here the derivatized fullerenes covalently bound to silica particles with different pore sizes are applied as thin layer for laser desorption/ionization (LDI) mass spectrometric analysis. Thus, an interference of intrinsic matrix ions can be eliminated or minimized in comparison with the state-of-the-art weak organic acid matrices. The desorption/ionization ability of the developed fullerene-silica materials depends on the applied laser power, sample preparation and pore size of the silica particles. Thus, fullerene-silica serves as an LDI support for mass spectrometric analysis of molecules (<1500 Da). The performance of the fullerene-silica is demonstrated by the mass analysis of variety of small molecules such as carbohydrates, amino acids, peptides, phospholipids and drugs.

Analytical strategies for characterizing the surface chemistry of nanoparticles

Chemical modifications of nanoparticle (NP) surfaces are likely to regulate their activities, remove their toxic effects, and enable them to perform desired functions. It is urgent to develop analytical strategies for acquiring structural and quantitative information about small molecules linked to the surface of NP. Recent progress in characterizing the surface chemistry of NPs using nuclear magnetic resonance (NMR) spectroscopy, Fourier-transform infrared (FTIR) spectroscopy, liquid chromatography-mass spectroscopy (LC-MS), X-ray photoelectron spectroscopy (XPS), and combustion elemental analysis are reviewed.

Novel possibilities in the study of isolated carbon nanotubes

We report the first detection of carbon nanotubes in the gas phase in a matrix-assisted laser desorption/ionization (MALDI) mass spectrometric experiment. These observations open the possibility of studying isolated nanotubes in the gas phase by means of various spectroscopic methods and a possible way to separate them.

Role of carbon nano-materials in the analysis of biological materials by laser desorption/ionization-mass spectrometry

At present, carbon nano-materials are being utilized in various procedures, especially in laser desorption/ionization-mass spectrometry (LDI-MS) for analyzing a range of analytes, which include peptides, proteins, metabolites, and polymers. Matrix-oriented LDI-MS techniques are very well established, with weak organic acids as energy-absorbing substances. Carbon materials, such as nano-tubes and fullerenes are being successfully applied in the small-mass range, where routine matrices have strong background signals. In addition, the role of carbon nano-materials is very well established in the fractionation and purification fields. Modified diamond powder and surfaces are utilized in binding peptides and proteins from complex biological fluids and analyzed by matrix-assisted laser desorption/ionization (MALDI) time-of-flight (TOF) mass spectrometry (MS). Polylysine-coated diamond is used for solid-phase extraction to pre-concentrate DNA oligonucleotides. Graphite is useful for desalting, pre-concentration, and as energy-absorbing material (matrix) in desorption/ionization. Carbon nano-tubes in their different derivatized forms are used as matrix materials for the analysis of a range of analytes, such as carbohydrates, amino acids, peptides, proteins, and some environmental samples by LDI-MS. Fullerenes are modified in different ways to bind serum entities analyzed through MALDI/TOF-MS and are subsequently utilized in their identifications. In addition, the fullerenes are a promising matrix in LDI-MS, but improvements are needed.

Nano-structured support materials, their characterisation and serum protein profiling through MALDI/TOF-MS

In the bioanalytical era, novel nano-materials for the selective extraction, pre-concentration and purification of biomolecules prior to analysis are vital. Their application as affinity binding in this regard is needed to be authentic. We report here the comparative application of derivatised materials and surfaces on the basis of nano-crystalline diamond, carbon nanotubes and fullerenes for the analysis of marker peptides and proteins by material enhanced laser desorption ionisation mass spectrometry MELDI-MS. In this particular work, the emphasis is placed on the derivatization, termed as immobilised metal affinity chromatography (IMAC), with three different support materials, to show the effectiveness of MELDI technique. For the physicochemical characterisation of the phases, near infrared reflectance spectroscopy (NIRS) is used, which is a well-established method within the analytical chemistry, covering a wide range of applications. NIRS enables differentiation between silica materials and different fullerenes derivatives, in a 3-dimensional factor-plot, depending on their derivatizations and physical characteristics. The method offers a physicochemical quantitative description in the nano-scale level of particle size, specific surface area, pore diameter, pore porosity, pore volume and total porosity with high linearity and improved precision. The measurement takes only a few seconds while high sample throughput is guaranteed.

Current literature in mass spectrometry

In order to keep subscribers up‐to‐date with the latest developments in their field, John Wiley & Sons are providing a current awareness service in each issue of the journal. The bibliography contains newly published material in the field of mass spectrometry. Each bibliography is divided into 11 sections: 1 Books, Reviews & Symposia; 2 Instrumental Techniques & Methods; 3 Gas Phase Ion Chemistry; 4 Biology/Biochemistry: Amino Acids, Peptides & Proteins; Carbohydrates; Lipids; Nucleic Acids; 5 Pharmacology/Toxicology; 6 Natural Products; 7 Analysis of Organic Compounds; 8 Analysis of Inorganics/Organometallics; 9 Surface Analysis; 10 Environmental Analysis; 11 Elemental Analysis. Within each section, articles are listed in alphabetical order with respect to author (6 Weeks journals ‐ Search completed at 4th. Oct. 2006)

Identification of carbohydrates by matrix-free material-enhanced laser desorption/ionisation mass spectrometry

Matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF-MS) is a sensitive mass spectrometric technique which utilises acidic materials as matrices for laser energy absorption, desorption and ionisation of analytes. These matrix materials produce background signals particularly in the low-mass range and make the detection and identification of small molecules difficult and nearly impossible. To overcome this problem this paper introduces matrix-free material-enhanced laser desorption/ionisation mass spectrometry (mf-MELDI-MS) for the screening and analysis of small molecules such as carbohydrates. For this purpose, 4,4'-azo-dianiline was immobilised on silica gel enabling the absorption of laser energy sufficient for successful desorption and ionisation of low molecular weight compounds. The particle and pore sizes, the solvent system for suspension and the sample preparation procedures have been optimised. The newly synthesised MELDI material delivered excellent spectra with regard to signal-to-noise ratio and detection sensitivity. Finally, wheat straw degradation products and Salix alba L. plant extracts were analysed proving the high performance and excellent behaviour of the introduced material.

Surfactant-mediated matrix-assisted laser desorption/ionization time-of-flight mass spectrometry of small molecules

A variety of surfactants have been tested as matrix-ion suppressors for the analysis of small molecules by matrix-assisted laser desorption/ionization time-of flight mass spectrometry. Their addition to the common matrix alpha-cyano-4-hydroxycinnamic acid (CHCA) greatly reduces the presence of matrix-related ions when added at the appropriate mole ratio of CHCA/surfactant, while still allowing the analyte signal to be observed. A range of cationic quaternary ammonium surfactants, as well as a neutral and anionic surfactant, was tested for the analysis of phenolics, phenolic acids, peptides and caffeine. It was found that the cationic surfactants, particularly cetyltrimethylammonium bromide (CTAB), were suitable for the analysis of acidic analytes. The anionic surfactant, sodium dodecyl sulfate, showed promise for peptide analysis. For trialanine, the detection limit was observed to be in the 100 femtomole range. The final matrix/surfactant mole ratio was a critical parameter for matrix ion suppression and resulting intensity of analyte signal. It was also found that the mass resolution of analytes was improved by 25-75%. Depth profiling of sample spots, by varying the number of laser shots, revealed that the surfactants tend to migrate toward the top of the droplet during crystallization, and that it is likely that the analyte is also enriched in this surface region. Here, higher analyte/surfactant concentration would reduce matrix-matrix interactions (known to be a source of matrix-derived ions).

Recent developments in methods and technology for analysis of biological samples by MALDI-TOF-MS

Matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF-MS) is widely used in a variety of fields because it has the characteristics of speed, ease of use, high sensitivity, and wide detectable mass range for obtaining molecular weights and for structural characterization of macromolecules. In this article we summarize recent developments in matrix additives, new matrices, and sample-pretreatment methods using off-probe or on-probe techniques or nanomaterials for MALDI-TOF-MS analysis of biological samples.

Ultra-fast mass fingerprinting by high-affinity capture of peptides and proteins on derivatized poly(glycidyl methacrylate/divinylbenzene) for the analysis of serum and cell lysates

The development of support materials in mass fingerprinting is an important task required for diagnostic markers in conjunction with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). The material-based approach, which we introduced as material-enhanced laser desorption/ionization (MELDI), focuses not only on different functionalities, but also emphasizes the morphology, i.e. porosity or particle size of the carrier material. As a result, it provides a quick and sensitive platform for effective binding of peptides and proteins out of different biofluids, e.g. serum, spinal fluid, urine or cell lysates, and to subsequently analyze them with MALDI-TOF MS. This approach includes a built-in desalting step for serum protein profiling and is sensitive enough to detect proteins and peptides down to 100 fmol/microL. Here we co-polymerized glycidyl methacrylate (GMA) with divinylbenzene (DVB) using thermal polymerization to yield a GMA/DVB polymer for further modifications. Different affinities have been created, such as immobilized metal ion affinity (IDA-Cu2+), reversed-phase (RP) and anion-exchanger (AX) chromatography. The diverse derivatizations and the dispersity of the particles created by different chemical synthetic approaches were confirmed by characteristic infrared (IR) peaks. The polymerization carried out by non-stirring yielded an average pore radius of 6.1 microm (macro-pores) that enhanced the binding capacity enormously by offering enlarged surface areas. Moreover, atomic absorption spectrometry (AAS) provided the metal content loaded on iminodiacetic acid (IDA) in the case of poly(GMA/DVB)-IDA-Cu2+. To summarize, the optimized MELDI approach is sensitive in its performance, extremely fast and can be adapted to robotic systems for routine analysis, allowing sample preparation in less than 5 min in contrast to the conventional surface-enhanced laser desorption/ionization (SELDI) methods.