Metal-Organic Frameworks in Bioanalysis: Extraction of Small Organic Molecules

Practicality evaluation of novel microextraction techniques for the determination of PFAS in food and water samples using the Blue Applicability Grade Index

BACKGROUND

Due to their high stability, persistence, and non-degradability, per- and polyfluoroalkyl substances (PFAS) are considered to be "forever chemicals" that can be present in a wide range of samples. Towards the development of novel analytical strategies for the reduction of the environmental impact of the analytical scheme, a plethora of novel solid-phase microextraction and miniaturized extraction techniques have been proposed for the determination of PFAS. However, the evaluation of the applicability of these protocols in terms of their practicality is still scarce.

RESULTS

In this article, the Blue Analytical Grade Index (BAGI) was used to evaluate the practicality of the sorbent-based microextraction techniques that were developed during the last decade for PFAS. In total thirty-four protocols were evaluated, resulting in a minimum score of 50.0 and a maximum score of 77.5.

SIGNIFICANCE

These findings clearly indicate that there is significant room for improvement and there is still a need for the development of microextraction approaches with higher practicality. Moreover, with regards to the best-performing protocols, their greenness was also assessed using the AGREEprep metric to enable a more comprehensive comparison.

Saliva analysis using metal-organic framework-coated miniaturized vials

BACKGROUND

In-vial microextraction is probably the simplest microextraction technique because it eliminates centrifugation and/or filtration steps while offering short extraction and desorption times. However, it has had limited applicability, mostly involving polydimethylsiloxane coatings and gas chromatography applications. Quite recently, one study introduced metal-organic framework (MOF)-coated glass vials for environmental analyses and liquid chromatography, thus combining the advantages of MOFs as adsorbents with the advantages of the in-vial approach, while not limiting the application to volatile analyses. Besides, a much higher exposure of the MOF to the sample due to the thin film coating available within the vial's inner walls is attained. Clearly, the applicability of this format for bioanalysis has not been evaluated, as there are not many stable and reusable sorbents useful for biological samples presenting high protein content. Besides, the in-vial technique must demonstrate to be valid for low-availability samples, such as saliva.

RESULTS

A vial with 2 mL-capacity and coated uniformly with a MOF has been developed to analyze saliva in a thin film solid-phase microextraction approach, while keeping an adequate analytical performance using only 50 μL of solvent for desorption. The procedure only requires 12.5 min of operation. Interestingly, the issues related to pore-blocking of the crystalline materials by proteins present in the saliva samples are solved with a simple cleaning protocol that also ensures a high reusability of the vials (more than 50 times). Seven bisphenols were determined in saliva with these devices, reaching limits of detection down to 0.10 μg L-1, and with inter-vial and inter-day precision values as RSD (in %) lower than 15% at a low concentration level (2.0 μg L-1).

SIGNIFICANCE

A device is presented to analyze complex saliva samples with a novel miniaturized MOF-coated vial ensuring proper reusability, while addressing the challenge of protein clogging and, at the same time, keeping adequate analytical performance with short analysis times. This approach represents significant progress in the bioanalytical sample preparation field, particularly when using sorbent porous materials integrated within miniaturized devices.

Advances in green sample preparation methods for bioanalytical laboratories focusing on drug analysis

Bioanalytical laboratories face significant challenges in sample preparation due to the complexity of biological matrices and the low concentrations of target analytes. This review focuses on advances in green sample preparation (GSP) techniques tailored to meet these challenges while promoting sustainability. Innovations in sorbents, including metal-organic frameworks (MOFs), magnetic nanoparticles (MNPs), sol-gel-based materials, molecularly imprinted polymers (MIPs), carbon-based materials, and natural sorbents like cellulose and kapok fiber, have enhanced extraction efficiency and selectivity. Green solvents such as deep eutectic solvents (DES), ionic liquids (ILs), supramolecular solvents (SUPRAs), and switchable hydrophilicity solvents (SHSs) further reduce environmental impact by minimizing toxic solvent use. This review highlights their use in drug analysis, emphasizing their roles in enhancing extraction efficiency, selectivity, and environmental sustainability. Recent applications demonstrate the integration of these sorbents and solvents into bioanalytical workflows, significantly improving analytical performance while adhering to Green Analytical Chemistry (GAC) principles. It is anticipated that this comprehensive review will aid scholars in the formulation of selective, rapid, environmentally friendly, straightforward, sensitive, and precise analytical methodologies for bioanalysis, thereby promoting innovation and sustainability within drug analysis protocols.

Recent Advances in Bioanalysis of Cephalosporins Toward Green Sample Preparation

This review highlights recent advances in the bioanalysis of cephalosporins using liquid chromatographic methods, focusing on green sample preparation (GSP) techniques. Cephalosporins, a class of β-lactam antibiotics, are critical in combating bacterial infections but present challenges related to drug resistance and toxicity. This article evaluates various sample preparation methods, including solid-phase extraction, solid-phase microextraction, and protein precipitation, which have been employed in the extraction and quantification of cephalosporins from biological matrices. Special attention is given to the optimization of critical parameters, such as pH, extraction solvents, and purification techniques to maximize analytes' recovery and sensitivity. Emerging trends in GSP, such as the use of molecularly imprinted polymers and miniaturized processing devices, are also discussed. The review underscores the growing importance of integrating environmentally friendly approaches in cephalosporin bioanalysis, paving the way for future innovations in bioanalytical research.

Virucidal activity of porphyrin-based metal-organic frameworks against highly pathogenic coronaviruses and hepatitis C virus

The antiviral effect of four porphyrin-based Metal-Organic Frameworks (PMOFs) with Al and Zr, namely Al-TCPP, PCN-222, PCN-223 and PCN-224 was assessed for the first time against HCoV-229E, two highly pathogenic coronaviruses (SARS-CoV-2 and MERS-CoV) and hepatitis C virus (HCV). Infection tests in vitro were done under dark or light exposure for different contact times, and it was found that 15 min of light exposure were enough to give antiviral properties to the materials, therefore inactivating HCoV-229E by 99.98 % and 99.96 % for Al-TCPP and PCN-222. Al-TCPP diminished the viral titer of SARS-CoV-2 greater than PCN-222 in the same duration of light exposure, having an effect of 99.95 % and 93.48 % respectively. Next, Al-TCPP was chosen as the best candidate possessing antiviral properties and was tested against MERS-CoV and HCV, showcasing a reduction of infectivity of 99.28 % and 98.15 % respectively for each virus. The mechanism of the antiviral activity of the four PMOFs was found to be the production of singlet oxygen 1O2 from the porphyrin ligand TCPP when exposed to visible light, by using sodium azide (NaN3) as a scavenger, that can later attack the phospholipids on the envelope of the viruses, thus preventing their entry into the cells.

Metal-organic frameworks in chiral separation of pharmaceuticals

Stereoselective chiral molecules are responsible for specific biological functions in nature. At present, more than half of the prescribed drugs are chiral. Living organisms display divergent pharmacological responses to the enantiomers, leading to altered toxicity, pharmacokinetics, and pharmacodynamics. Thus, chiral analysis, separation, and extraction are crucial for ensuring enantiomeric purity to develop safe and effective medication. In recent times, metal-organic frameworks (MOFs) with appealing structures are gaining importance because of their fascinating properties as a sorbent and stationary phase. MOFs are crystalline porous solid materials built by interconnecting metal ions or clusters and organic linkers. This review explores the advancements in MOFs for the isolation and separation of chiral active pharmaceutical drugs.

Effect of Geometrical Parameters on Extraction Efficiency of the Annular Centrifugal Contactor

The geometrical parameters of annular centrifugal contactors (ACCs) have an important influence on the extraction efficiency. The present work used a home-made 25 mm ACC constructed by 3D printing to investigate the effect of five geometrical parameters on the extraction efficiency. These parameters are annular width (d), clearance height (Hc), rotor inlet diameter (Din), bottom vane number (N), and the bottom vane’s bending direction (S). Central composite design was employed to design the experiment, and the response surface methodology was used to analyze the data. The results show that Hc and Din were positive for efficiency, while d and N were negative. When the bottom vane’s bending direction was the same as the liquid helical flow direction, the efficiency improved compared to the straight vane. It is found that 3 mm d, 5 mm Hc, 6 mm Din, and four clockwise covered vanes are the parameters where the efficiency reached the highest point of 94.5%. We analyzed the interactions between the parameters based on the coefficients of the quadratic equation, and the interactions were not considered in previous studies. This work surprisingly reveals that the effects of the parameters on the extraction efficiency were not independent, and there were interactions between the parameters. The interaction between the rotor inlet diameter and annular width was significant and could not be ignored. These results could serve as a reference for optimizing extraction processes and the design of ACCs.