Ion trap mass spectrometry of fluorescently labeled nanoparticles

Revisiting the Green Synthesis of Nanoparticles: Uncovering Influences of Plant Extracts as Reducing Agents for Enhanced Synthesis Efficiency and Its Biomedical Applications

Background

Conventional nanoparticle synthesis methods involve harsh conditions, high costs, and environmental pollution. In this context, researchers are actively searching for sustainable, eco-friendly alternatives to conventional chemical synthesis methods. This has led to the development of green synthesis procedures among which the exploration of the plant-mediated synthesis of nanoparticles experienced a great development. Especially, because plant extracts can work as reducing and stabilizing agents. This opens up new possibilities for cost-effective, environmentally-friendly nanoparticle synthesis with enhanced size uniformity and stability. Moreover, bio-inspired nanoparticles derived from plants exhibit intriguing pharmacological properties, making them highly promising for use in medical applications due to their biocompatibility and nano-dimension.

Objective

This study investigates the role of specific phytochemicals, such as phenolic compounds, terpenoids, and proteins, in plant-mediated nanoparticle synthesis together with their influence on particle size, stability, and properties. Additionally, we highlight the potential applications of these bio-derived nanoparticles, particularly with regard to drug delivery, disease management, agriculture, bioremediation, and application in other industries.

Methodology

Extensive research on scientific databases identified green synthesis methods, specifically plant-mediated synthesis, with a focus on understanding the contributions of phytochemicals like phenolic compounds, terpenoids, and proteins. The database search covered the field's development over the past 15 years.

Results

Insights gained from this exploration highlight plant-mediated green synthesis for cost-effective nanoparticle production with significant pharmacological properties. Utilizing renewable biological resources and controlling nanoparticle characteristics through biomolecule interactions offer promising avenues for future research and applications.

Conclusion

This review delves into the scientific intricacies of plant-mediated synthesis of nanoparticles, highlighting the advantages of this approach over the traditional chemical synthesis methods. The study showcases the immense potential of green synthesis for medical and other applications, aiming to inspire further research in this exciting area and promote a more sustainable future.

Applications of Charge Detection Mass Spectrometry in Molecular Biology and Biotechnology

Charge detection mass spectrometry (CDMS) is a single-particle technique where the masses of individual ions are determined from simultaneous measurement of their mass-to-charge ratio (m/z) and charge. Masses are determined for thousands of individual ions, and then the results are binned to give a mass spectrum. Using this approach, accurate mass distributions can be measured for heterogeneous and high-molecular-weight samples that are usually not amenable to analysis by conventional mass spectrometry. Recent applications include heavily glycosylated proteins, protein complexes, protein aggregates such as amyloid fibers, infectious viruses, gene therapies, vaccines, and vesicles such as exosomes.

Weighing synthetic polymers of ultra-high molar mass and polymeric nanomaterials: What can we learn from charge detection mass spectrometry?

Advances in soft ionization techniques for mass spectrometry (MS) of polymeric materials make it possible to determine the masses of intact molecular ions exceeding megadaltons. Interfacing MS with separation and fragmentation methods has additionally led to impressive advances in the ability to structurally characterize polymers. Even if the gap to the megadalton range has been bridged by MS for polymers standards, the MS-based analysis for more complex polymeric materials is still challenging. Charge detection mass spectrometry (CDMS) is a single-molecule method where the mass and the charge of each ion are directly determined from individual measurements. The entire molecular mass distribution of a polymer sample can be thus accurately measured. Described in this perspective paper is how molecular weight distribution as well as charge distribution can provide new insights into the structural and compositional studies of synthetic polymers and polymeric nanomaterials in the megadalton to gigadalton range of molecular weight. The recent multidimensional CDMS studies involving couplings with separation and dissociation techniques will be presented. And, finally, an outlook for the future avenues of the CDMS technique in the field of synthetic polymers of ultra-high molar mass and polymeric nanomaterials will be provided.

A quadrupole ion trap mass spectrometer for dry microparticle analysis

In this work, we report a new design of a charge detection quadrupole ion trap mass spectrometer (QIT-MS) for the analysis of micro-sized dry inorganic and bioparticles including red blood cells (RBCs) and different sizes of MCF-7 breast cancer cells. The developed method is one of the fastest methods to measure the mass of micro-sized particles. This system allows the online analysis of various micro-sized particles up to 1 × 10¹⁷ Da. The calibration of the mass spectrometer has been done by using different sizes of polystyrene (PS) particles (2-15 μm). The measured masses of RBCs were around 1.8 × 10¹³ Da and MCF-7 cancer cells were between 1 × 10¹⁴ and 4 × 10¹⁴ Da. The calculated mass distribution profiles of the particles and cells were given as histogram profiles. The statistical data were summarized after Gaussian type fitting to the experimental histogram profiles. The new method gives very promising results for the analysis of particles and has very broad application.

Single-molecule mass spectrometry

In single-molecule mass spectrometry, the mass of each ion is measured individually; making it suitable for the analysis of very large, heterogeneous objects that cannot be analyzed by conventional means. A range of single-molecule mass spectrometry techniques has been developed, including time-of-flight with cryogenic detectors, a quadrupole ion trap with optical detection, single-molecule Fourier transform ion cyclotron resonance, charge detection mass spectrometry, quadrupole ion traps coupled to charge detector plates, and nanomechanical oscillators. In addition to providing information on mass and heterogeneity, these techniques have been used to study impact craters from cosmic dust, monitor the assembly of viruses, elucidate the fluorescence dynamics of quantum dots, and much more. This review focuses on the merits of each of these technologies, their limitations, and their applications. © 2016 Wiley Periodicals, Inc. Mass Spec Rev 36:715-733, 2017.

Computer simulations of a new toroidal-cylindrical ion trap mass analyzer

RATIONALE

A novel toroidal-cylindrical ion trap (TCIT) design is introduced based on a compact dual ion trap system that comprises an outer toroidal ion trap (T-trap) and an inner cylindrical ion trap (CIT). These two traps have specific but different functions that can improve the performance of tandem mass analysis operation.

METHODS

The TCIT is studied by using a simulated mass spectrometer platform that is mainly based on SIMION modeling and extensive data processing. This platform combines different functions, such as simulation of ion motion and field calculations, as well as acquisition of a simulated mass spectrum.

RESULTS

The main steps of the MS operation, including the full scan process, the mass-selective ejection of the ions in the T-trap, and the capture of the injected precursor ions in the CIT, are realized using the abovementioned platform. In addition, the simulated design is optimized for improved mass analysis performance.

CONCLUSIONS

For the outer T-trap, when the outside surface of the inner cylindrical electrode is modified to include a circular arc with appropriate radius, the ion ejection efficiency that is directed into the CIT could be significantly enhanced. In the case of the inner CIT, the ion capture efficiency could be improved to more than 90% with geometry optimization. Copyright © 2016 John Wiley & Sons, Ltd.

Photoluminescence of charged CdSe/ZnS quantum dots in the gas phase: effects of charge and heating on absorption and emission probabilities

Gas phase spectral measurements for CdSe/ZnS core/shell nanocrystal quantum dots (QDs) before and after heating with both infrared (CO2) and visible lasers are reported. As-trapped QDs are spectrally similar to the same QDs in solution; however their photoluminescence (PL) intensities are very low, at least partly due to low absorption cross sections. After heating, the PL intensities brighten by factors ranging from ∼4 to 1800 depending on the QD size and pump laser wavelength. The emission spectra no longer resemble solution spectra and are similar, regardless of the QD diameter. Emission extends from the pump laser wavelength into the near-IR, with strong emission features above the band gap energy, between 645 and 775 nm, and in the near-infrared. Emission spectra from brightened QD ensembles, single QD aggregates, and single QD monomers are similar, showing that even single QDs support PL from a wide variety of states. The heating and cooling processes for QDs in this environment are analyzed, providing limits on the magnitudes of the absorption cross sections before and after thermal brightening. A model, based on absorption bleaching by extra electrons in the conduction band, appears to account for the changes in absorption and emission behavior induced by charging and heating.

Optically detected, single nanoparticle mass spectrometer with pre-filtered electrospray nanoparticle source

An instrument designed for non-destructive mass analysis of single trapped nanoparticles is described. The heart of the instrument is a 3D quadrupole (Paul) trap constructed to give optical access to the trap center along ten directions, allowing passage of lasers for particle heating and detection, particle injection, collection of scattered or fluorescent photons for particle detection and mass analysis, and collection of particles on TEM grids for analysis, as needed. Nanoparticles are injected using an electrospray ionization (ESI) source, and conditions are described for spraying and trapping polymer particles, bare metal particles, and ligand stabilized particles with masses ranging from 200 kDa to >3 GDa. Conditions appropriate to ESI and injection of different types of particles are described. The instrument is equipped with two ion guides separating the ESI source and nanoparticle trap. The first ion guide is mostly to allow desolvation and differential pumping before the particles enter the trap section of the instrument. The second is a linear quadrupole guide, which can be operated in mass selective or mass band-pass modes to limit transmission to species with mass-to-charge ratios in the range of interest. With a little experience, the design allows injection of single particles into the trap upon demand.

The development of charge detection-quadrupole ion trap mass spectrometry driven by rectangular and triangular waves

In this article, the charge detection quadrupole mass spectrometry (CD-ITMS) driven by rectangular and triangular waveforms (rect-CD-ITMS and tri-CD-ITMS) was developed for the characterization of microparticles. Since the frequency scan of rectangular and triangular waveform could be realized easier than that of sinusoidal waveform, this research intends to provide simpler operation modes for CD-ITMS. In order to demonstrate the feasibility of rect-CD-ITMS and tri-CD-ITMS, the discharge onset voltage, ejection point of analyzed particles, and the achieved mass resolution were analyzed and compared with the case in conventional sinusoidal CD-ITMS (sin-CD-ITMS). The results indicated that the rect-CD-ITMS and tri-CD-ITMS can work well for the mass measurement of microparticles by using frequency scan. Identical mass resolutions were achieved under the same root mean square (RMS) voltage of different waveforms. The mass resolution was further improved by increasing the applied voltage and signal-to-noise ratio (S/N) of charge detector. Moreover, the rect-CD-ITMS and tri-CD-ITMS were applied to characterize red blood cells (RBCs). According to the obtained mean masses and mass distributions, normal and anemic RBCs were distinguished successfully.

Ultrahigh-mass mass spectrometry of single biomolecules and bioparticles

Since the advent of soft ionization methods, mass spectrometry (MS) has found widespread application in the life sciences. Mass is now known to be a critical parameter for characterization of biomolecules and their complexes; it is also a useful parameter to characterize bioparticles such as viruses and cells. However, because of the genetic diversity of these entities, it is necessary to measure their masses individually and to obtain the corresponding mean masses and mass distributions. Here, I review recent technological developments that enable mass measurement of ultrahigh-mass biomolecules and bioparticles at the single-ion level. Some representative examples include cryodetection time-of-flight MS of single-megadalton protein ions, Millikan-type mass measurements of single viruses in a cylindrical ion trap, and charge-detection quadrupole ion trap MS of single whole cells. I also discuss the promises and challenges of these new technologies in real-world applications.

Trap for MAbs: characterization of intact monoclonal antibodies using reversed-phase HPLC on-line with ion-trap mass spectrometry

For the first time, the characterization of intact 150-kDa monoclonal antibodies (MAbs) using a commercially available three-dimensional ion-trap mass spectrometer (IT-MS) is reported. The IT-MS analysis was performed on-line with reversed-phase high performance liquid chromatography (RP-HPLC) on a POROS column using a nontraditional solvent system of acetonitrile, isopropanol, ethanol, and water in formic acid. The operating parameters of the IT-MS were optimized by extending the mass range to m/z 4000 and elevating the tube lens offset voltage value to around -100 V. Mass accuracy better than 300 ppm (+/-40 Da) has been routinely achieved for these macromolecules. Multiple peaks 162 Da apart due to the hexose variants of the monoclonal IgG antibodies were partially resolved in mass spectra. Several commercial and chimeric antibodies have been investigated in this study.

Laser-induced fluorescence of trapped gas-phase molecular ions generated by internal source matrix-assisted laser desorption/ionization in a Fourier transform ion cyclotron resonance mass spectrometer

The combination of laser-induced fluorescence with mass spectrometry opens up new possibilities both for detection purposes and for structural studies of trapped biomolecular ions in the gas phase. However, this approach is experimentally very challenging, and only a handful of studies have been reported so far. In this contribution, a novel scheme for laser-induced fluorescence measurements of ions trapped inside a Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer will be introduced. It is based on an open FT-ICR cell design, continuous wave axial excitation of the fluorescence, orthogonal photon collection by fiber optics, and single photon counting detection. Rhodamine 6G ions generated by an internal matrix-assisted laser desorption/ionization source were used to develop and test the set-up. Due to photobleaching processes, the excitation laser power and the observation time window have to be carefully optimized. An ion tomography method was used to align the excitation laser. Potential applications for studying the gas-phase structure of fluorescent biomolecular ions and for investigating fluorescence resonance energy transfer of donor-acceptor pairs will be presented.

Optical detection methods for mass spectrometry of macroions

Detection of macroions has been a challenge in the field of mass spectrometry. Conventional ionization-based detectors, relying on production and multiplication of secondary electrons, are restricted to detection for charged particles of m/z < 1 x 10(6). While both energy-sensitive and charge-sensitive detectors have been developed recently to overcome the limitation, they are not yet in common use. Photon-sensitive detectors are suggested to be an alternative, with which detection of macroions (or charged particles) by either elastic light scattering (ELS) or laser-induced fluorescence (LIF) has been possible. In this article, we provide a critical review on the developments of novel optical detection methods for mass spectrometry of macroions, including both micron-sized and nano-sized synthetic polymers as well as high-mass biomolecules. Design and development of new spectrometers making possible observations of the mass spectra of macroions with sizes in the range of 10-10(3) nm or masses in the range of 1-10(6) MDa are illustrated. The potential and promise of this optical approach toward macroion detection with high efficiency are discussed in practical aspects.