Application of magnetic nanomaterials in bioanalysis

Engineering mesoporous bioactive glasses for emerging stimuli-responsive drug delivery and theranostic applications

Mesoporous bioactive glasses (MBGs), which belong to the category of modern porous nanomaterials, have garnered significant attention due to their impressive biological activities, appealing physicochemical properties, and desirable morphological features. They hold immense potential for utilization in diverse fields, including adsorption, separation, catalysis, bioengineering, and medicine. Despite possessing interior porous structures, excellent morphological characteristics, and superior biocompatibility, primitive MBGs face challenges related to weak encapsulation efficiency, drug loading, and mechanical strength when applied in biomedical fields. It is important to note that the advantageous attributes of MBGs can be effectively preserved by incorporating supramolecular assemblies, miscellaneous metal species, and their conjugates into the material surfaces or intrinsic mesoporous networks. The innovative advancements in these modified colloidal inorganic nanocarriers inspire researchers to explore novel applications, such as stimuli-responsive drug delivery, with exceptional in-vivo performances. In view of the above, we outline the fabrication process of calcium-silicon-phosphorus based MBGs, followed by discussions on their significant progress in various engineered strategies involving surface functionalization, nanostructures, and network modification. Furthermore, we emphasize the recent advancements in the textural and physicochemical properties of MBGs, along with their theranostic potentials in multiple cancerous and non-cancerous diseases. Lastly, we recapitulate compelling viewpoints, with specific considerations given from bench to bedside.

Nano-Micron Combined Hydrogel Microspheres: Novel Answer for Minimal Invasive Biomedical Applications

Hydrogels, key in biomedical research for their hydrophilicity and versatility, have evolved with hydrogel microspheres (HMs) of micron-scale dimensions, enhancing their role in minimally invasive therapeutic delivery, tissue repair, and regeneration. The recent emergence of nanomaterials has ushered in a revolutionary transformation in the biomedical field, which demonstrates tremendous potential in targeted therapies, biological imaging, and disease diagnostics. Consequently, the integration of advanced nanotechnology promises to trigger a new revolution in the realm of hydrogels. HMs loaded with nanomaterials combine the advantages of both hydrogels and nanomaterials, which enables multifaceted functionalities such as efficient drug delivery, sustained release, targeted therapy, biological lubrication, biochemical detection, medical imaging, biosensing monitoring, and micro-robotics. Here, this review comprehensively expounds upon commonly used nanomaterials and their classifications. Then, it provides comprehensive insights into the raw materials and preparation methods of HMs. Besides, the common strategies employed to achieve nano-micron combinations are summarized, and the latest applications of these advanced nano-micron combined HMs in the biomedical field are elucidated. Finally, valuable insights into the future design and development of nano-micron combined HMs are provided.

Magnetic separation-assisted cluster-amplified versatile fluorescent aptasensors for the sensitive detection of target biomolecules

A sensitive and versatile platform for detecting diverse target biomolecules was developed by combining a magnetic separation module and a fluorescence amplification module in a plug-and-play manner. The magnetic separation module was constructed using magnetic beads (MBs), whose surfaces were modified with aptamer-blocked captor DNAs. The fluorescence amplification module was constructed by loading the fluorescent dye rhodamine 6G (Rh6G) into the pores of mesoporous silica nanoparticles (MSNs). The MSN surfaces were modified with prey DNAs, of which the MSN-near ends hybridized with complementary DNAs (sealing DNAs) to form duplexes to seal the pores, and the free ends were designed to be single-stranded that were complementary to the captor DNAs. Upon binding of targets to their aptamers, the captor DNAs were unblocked and thus were able to hybridize with the prey DNAs, to capture Rh6G-laden MSNs, forming MB-MSN clusters. The clusters were isolated by magnetic separation and heated to dissociate the DNA duplexes, to unseal the MSN pores and release the inner Rh6G; thus a target was converted into a cluster of Rh6G dyes. By simply changing the target aptamers and related DNA connectors, this strategy detected ATP, thrombin, and platelet-derived growth factor BB with detection limits of 2.1 nM, 4.1 pM, and 2.4 pM, respectively. A wide range of targets, high amplification efficiency and universal functional modules endow the aptasensors with good potential as versatile platforms for detecting target molecules in vitro and in medical research.

Remediation of copper and lead contaminated sediments using iron-based granule biochar: mechanisms and enzyme activity

In recent years, there has been a growing concern about heavy metal contamination in sediments. In this study, iron-based granular biochar (MGB) is prepared to remediate Cu and Pb contaminated sediments. Characterizations via scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) show that the rough surface of MGB with abundant pore structures and a large number of oxygen-containing functional groups that facilitate stabilization of Cu and Pb in sediments. Potential mobility and bioavailability of Cu and Pb are investigated using BCR sequential extraction in the 35 day remediation experiment. The XPS results indicate that FeOOH and C-OH play a crucial part in stabilizing heavy metals. Large affinity of FeOOH for Pb allows it to occupy a proportion in F₂ while C-OH is attractive to Cu. Changes of pH, organic matter (OM), and available phosphorus (AP) in sediments after adding MGB as well as the relationship between changes and the stable solidification of Cu and Pb are explored. The stable solidification of heavy metals effectively reduces the available phosphorus in sediments. Magnetic and particle properties of the material are used to reduce the impact of MGB aging on sediment environment and separate it from the remediated sediment. Finally, 3% of MGB significantly enhanced the sediment catalase activity in the biological enzyme activity experiment. All findings indicate that MGB is a green and environmentally friendly sediment remediation material with satisfactory potential in synergistically stabilizing heavy metals and phosphorus.Highlights The complexation of FeOOH with Pb on the surface of MGB fixes it to the reduced stateThe C-OH on the surface of MGB is more attractive to Cu than PbMGB effectively mitigates the release of bioavailable phosphorus from sediments to overlying water.

Coupling in-syringe kapok fiber-supported liquid-phase microextraction with flow injection-mass spectrometry for rapid and green biofluid analysis: Determination of antidepressants as an example

Quantification of substances in biofluid samples (e.g., urine, blood, and cerebrospinal fluids) are useful for clinical diagnosis. In current study, a rapid and green strategy by coupling in-syringe kapok fiber-supported liquid-phase microextraction with flow-injection mass spectrometry was proposed. The natural kapok fiber was used as an oily extraction solvent (e.g., n-octanol) support material, and an in-syringe extraction device was conveniently constructed. The whole extraction processes, including sampling, washing and desorption, were conveniently conducted by simply pulling/pushing the syringe plunger, enabling rapid analyte enrichment and sample purification. The follow-up flow injection-mass spectrometry detection enabled rapid and high throughput analysis. As an example, the proposed method was applied to analyze antidepressants in plasma/urine, showing satisfied linearities (R² ≥0.993) in ranges of 0.2-1000 ng/mL. By employing the in-syringe extraction method prior to flow injection-mass spectrometry detection, the LOQs in plasma and urine were reduced by 25-80 folds and 5-25 folds, respectively. Besides, by employing ethanol and 80% ethanol as the desorption solvent and carrier solvent, respectively, the analytical method showed excellent greenness. In general, the integrated method provides a promising choice for rapid and green biofluid analysis.

Study on the biological effects of ZnO nanosheets on EBL cells

In this study, the biological effects of ZnO nanosheets were initially investigated using embryonic bovine lung (EBL) cells cultured in vitro as a model. ZnO nanosheets were prepared by a hydrothermal method, and their structure and morphology were characterized, and their effects on EBL cell viability, oxidative stress, cell proliferation, and apoptosis were investigated. The results showed that 12.5 μg ml⁻¹ ZnO nanosheets can cause morphological changes in EBL cells. The toxic effects of ZnO nanosheets on EBL cells were time-dependent. Caspase-3 activity in EBL cells changed under certain conditions with the introduction of 25 μg ml⁻¹ ZnO nanomaterials, and EBL cell apoptosis was promoted. Under different concentration and time effects, ZnO nanosheets induced an increase in ROS levels in EBL cells, indicating that they have an oxidative damage effect on cells. The toxic effects of ZnO nanosheets on EBL cells were discussed, including concentration effect, time effect, and cytotoxic effect, which eventually led to cell oxidative damage.

Terminal deoxynucleotidyl transferase associated with split G-quadruplex/hemin deoxyribozyme amplification detection for various contaminants in milk based on pregnancy test strip platform

Contaminant residue analysis in milk can provide essential assistance for safety quality and contamination level management of milk production, which is critical for safeguarding public health. In this study, the pregnancy test strip is employed to achieve multiple analytes detection based on the specific recognition of aptamer and terminal deoxynucleotidyl transferase associated with split G-quadruplex/hemin deoxyribozyme system. Through the subsequent enzyme catalyzed reaction, the detection signal can be further amplified to improve the sensitivity. The method does not need to assemble test strip, prepare and purify antibodies/haptens, nor design complex probe sequences. By coupling human chorionic gonadotrophin with DNA probes and combining magnetic separation technology, the targets can be determined via the test strip. Under the optimized conditions, the visual detection limits for mercury ion, bisphenol A, and penicillin are 1, 0.1 and 0.05 nM, respectively. The detection results show that the method displays good accuracy and practicability in spiked milk sample. The method presents a simple scheme, low cost as well as good design versatility, which demonstrates great application prospect for the sensitive, low-cost, and convenient detection of food matrices.

Construction of PEGylated boronate-affinity-oriented imprinting magnetic nanoparticles for ultrasensitive detection of ellagic acid from beverages

Molecularly imprinted polymers (MIPs) can exhibit antibody-level affinity for target molecules. However, the nonspecific adsorption of non-imprinted regions for non-target molecules limits the application range of MIPs. Herein, we fabricated PEGylated boronate-affinity-oriented ellagic acid-imprinting magnetic nanoparticles (PBEMN), which first integrated boronate-affinity-oriented surface imprinting and sequential PEGylation for small molecule-imprinted MIPs. The resultant PBEMN possess higher adsorption capacity and faster adsorption rate for template ellagic acid (EA) molecules than the non-PEGylated control. To prove the excellent performance, the PBEMN were linked with hydrophilic boronic acid-modified/fluorescein isothiocyanate-loaded graphene oxide (BFGO), because BFGO could selectively label cis-diol-containing substances by boronate-affinity and output ultrasensitive fluorescent signals. Based on a dual boronate-affinity synergy, the PBEMN first selectively captured EA molecules by boronate-affinity-oriented molecular imprinted recognition, and then the EA molecules were further labeled with BFGO through boronate-affinity. The PBEMN linked BFGO (PBPF) strategy provided ultrahigh sensitivity for EA molecules with a limit of detection of 39.1 fg mL^-1, resulting from the low nonspecific adsorption of PBEMN and the ultrasensitive fluorescence signal of BFGO. Lastly, the PBPF strategy was successfully employed in the determination of EA concentration in a spiked beverage sample with recovery and relative standard deviation in the range of 96.5 to 104.2% and 3.8 to 5.1%, respectively. This work demonstrates that the integration of boronate-affinity-oriented surface imprinting and sequential PEGylation may be a universal tool for improving the performance of MIPs.

Immobilization of Alcohol Dehydrogenase, Acetaldehyde Lyase, and NADH Oxidase for Cascade Enzymatic Conversion of Ethanol to Acetoin

Acetoin, a four-carbon hydroxyl-keto compound, is used in the food, pharmaceutical, and chemical industries. The cascade enzymatic production is considered a promising and efficient method to produce acetoin. However, the stability and compatibility of the enzymes under the same catalytic conditions are challenges that need to be resolved. In this work, alcohol dehydrogenase, acetaldehyde lyase, and NADH oxidase were selected to work at the same conditions to efficiently convert ethanol into acetoin. These three enzymes were immobilized on epoxy-modified magnetic nanomaterials to obtain highly stable biocatalysts. The stability and the immobilization conditions, including temperature, pH, enzyme–carrier ratio, and immobilization time, were optimized to obtain the immobilized enzymes with a high catalytic activity. The cascade reactions catalyzed by the immobilized enzymes yielded a high conversion of 90%, suggesting that the use of immobilized enzymes is a promising way to produce acetoin.

Current development of bioanalytical sample preparation techniques in pharmaceuticals

Sample preparation is considered as the bottleneck step in bioanalysis because each biological matrix has its own unique challenges and complexity. Competent sample preparation to extract the desired analytes and remove redundant components is a crucial step in each bioanalytical approach. The matrix effect is a key hurdle in bioanalytical sample preparation, which has gained extensive consideration. Novel sample preparation techniques have advantages over classical techniques in terms of accuracy, automation, ease of sample preparation, storage, and shipment and have become increasingly popular over the past decade. Our objective is to provide a broad outline of current developments in various bioanalytical sample preparation techniques in chromatographic and spectroscopic examinations. In addition, how these techniques have gained considerable attention over the past decade in bioanalytical research is mentioned with preferred examples. Modern trends in bioanalytical sample preparation techniques, including sorbent-based microextraction techniques, are primarily emphasized.

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Bioanalytical sampling techniques are described with suitable applications in pharmaceuticals.

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The pros and cons of each bioanalytical sampling techniques are described.

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Relevant biological matrices are outlined.

A microfluidic approach for rapid and continuous synthesis of glycoprotein-imprinted nanospheres

Many strategies have been reported for the preparation of glycoproteins imprinted polymers, but they take a long time and cannot produce imprinted polymers continuously. Herein, a microfluidic synthesis approach was developed to make glycoproteins imprinted nanospheres rapidly and continuously. By using ovalbumin as a model template and a synthesized phenylboronic acid-tagged silane reagent as the functional monomer, the synthetic conditions including the polymerization contents, the flow rate and the microfluidic reactor size were comprehensively studied. Under the optimized conditions, the glycoprotein imprinted nanospheres could be synthesized rapidly (<2 h), and exhibited high specificity with cross-reactivity factors of 1.3 (ovotransferrin), +∞ (horse-radish peroxidase), 5.1 (β-lactoglobulin) and 101 (bovine serum albumin). The kinetic and equilibrium binding behaviors, reusability and potential applications of the glycoprotein imprinted nanosphere were investigated. Such microfluidic synthesis strategy can be easily extended to produce other target glycoproteins imprinted nanospheres, as well as non-glycoproteins by using suitable functional monomers.

A detection method of Escherichia coli O157:H7 based on immunomagnetic separation and aptamers-gold nanoparticle probe quenching Rhodamine B's fluorescence: Escherichia coli O157:H7 detection method based on IMS and Apt-AuNPs probe quenching Rho B' s fluorescence

This research aimed to detect Escherichia coli O157:H7 in milk based on immunomagnetic probe separation technology and quenching effect of gold nanoparticles to Rhodamine B. Streptavidin-modified magnetic beads (MBs) were combined with biotin-modified antibodies to capture E. coli O157:H7 specifically. Gold nanoparticle (AuNPs) was incubated with sulfhydryl-modified aptamers (SH-Aptamers) to obtain the Aptamers-AuNPs probe. After magnetic beads captured target bacteria and formed a sandwich structure with the gold nanoprobe, Rhodamine B was added into complex to obtain fluorescent signal changes. Our results demonstrated that the established method could detect E. coli O157:H7 in the range of 101-107 CFU/mL, and the limit of detection (LOD) was 0.35 CFU/mL in TBST buffer (pH = 7.4). In milk simulation samples, the LOD of this method was 1.03 CFU/mL. Our research provides a promising approach on the detection of E. coli O157:H7.