Nonspecific Absorption Research Articles

Molecular Effects of Zwitterionic Peptide on Monolayer Lipid Membranes upon Enzyme-Catalyzed Degradation.

Secretory phospholipase A2 (sPLA2), an enzyme overexpressed in numerous diseases, has been used to trigger structural transformations in lipid-based drug delivery systems, enabling payload release at target sites. Zwitterionic peptides are known for their superior antifouling properties, often outperforming poly(ethylene glycol) (PEG) surface modification by resisting protein adsorption. In this study, we examined lipid monolayers at the water-vapor interface on a Langmuir trough, incorporating varying molar fractions of zwitterionic peptide-conjugated lipids or PEG-conjugated lipids. Synchrotron X-ray surface techniques, including X-ray reflectivity and grazing incidence X-ray diffraction, were employed to analyze molecular packing, enzyme adsorption, enzyme-catalyzed lipid degradation, and metabolite reorganization at the interface, and microscopy was used to observe domain morphologies. The results demonstrate that zwitterionic peptides exhibit a significantly greater efficiency than PEG in stabilizing the interfacial monolayer packing structure against enzyme-catalyzed lipid degradation. However, contrary to most studies reporting strong resistance of zwitterionic materials to nonspecific protein absorption, enzyme absorption to the interface, which is interfacial and phospholipids specific, was not impeded by the presence of zwitterionic peptides at low molar ratios (≤10 mol %).

Protein absorption alters the cellular targeting of glycopolymeric nanoparticles

Glycopolymeric nanoparticles are widely employed in biomedical applications due to their high targeting ability, biocompatibility, and biodegradability. The pendant saccharides serve as targeting ligands to be explicitly coordinated to receptors on cell membrane surfaces. However, proteins in the blood often absorb onto the nanoparticle surface, potentially impacting the exposure and effectiveness of the saccharide ligands for targeted delivery. To elucidate the protein absorption effects, we prepared micelles decorated with different percentages of fructose moieties and evaluated the bioactivity of nanoparticles using 2D cell culture, tumor spheroid, liver organoid, and coculture models. The 2D cell culture model did not show a significant difference in activity between protein-coated and non-coated micelles. However, a dramatic decrease in cellular uptake and penetration ability of micelles was observed in 3D tumor spheroids after protein absorption. Additionally, protein absorption notably increased micelle uptake in liver organoids. In the coculture model, protein absorption reduced micelle uptake in tumor spheroids while favoring uptake in liver organoids. Our work suggests that decreasing non-specific protein absorption of glycopolymeric nanoparticles could enhance their delivery efficiency. These findings underscore the importance of understanding protein interactions in nanoparticle applications for drug delivery.

Specific isolation and quantification of PD-L1 positive tumor derived exosomes for accurate breast cancer discrimination via aptamer-functionalized magnetic composites and SERS immunoassay

PD-L1 positive tumor derived exosomes (TEXsPD−L1) play a significant role in disease progression, tumor metastasis and cancer immunotherapy. However, the overlap of PD-L1 between TEXs and non-tumor derived exosomes (non-TEXs) restricts the specific isolation and quantification of TEXPD−L1 from clinical samples. Herein, a new aptamer-functionalized and hydrophilic immunomagnetic substrate was designed by decorating generation 5 polyamidoamine dendrimers (G5 PAMAM), zwitterionic trimethylamine N-oxide (TMAO) and EpCAM (Epithelial cell adhesion molecule) aptamers on magnetic cores sequentially (Fe3O4@PAMAM@TMAO@Aptamer, named as FPTA) for rapid target and efficient capture of TEXs. The FPTA substrate gathered excellent characters of strong magnetic responsiveness of Fe3O4, abundant affinity sites of PAMAM, strong hydrophilicity of TMAO and enhanced affinity properties of EpCAM aptamers. Because of these advantages, FPTA can isolate TEXs quickly within 30min with high capture efficiency of 90.5 % ± 3.0 % and low nonspecific absorption of 8.2 % ± 2.0 % for non-TEXs. Furthermore, PD-L1 (Programmed cell death-ligand 1) positive TEXs (TEXsPD−L1) from the captured TEXs were recognized and quantitatively analyzed by utilizing SERS (surface-enhanced Raman spectroscopy) reporter molecules 4-NTP (4-Nitrothiophenol) on PD-L1 aptamers-functionalized gold immunoaffinity probe. The signal of TEXsPD−L1 was converted to SERS signal of 4-NTP at 1344 cm−1 which exhibited a linear correlation to concentration of TEXsPD−L1(R2 = 0.9905). With these merits, this strategy was further applied to clinical plasma samples from breast cancer (BC) patients and healthy controls (HC), exhibited an excellent diagnosis accuracy with area under curve (AUC) of receiver operating characteristic (ROC) curve reaching 0.988. All these results demonstrate that the FPTA immunomagnetic substrate combined with SERS immunoaffinity probe may become a generic tool for specific isolation and quantitative analysis of PD-L1 positive tumor-derived exosomes in clinics.

Boronic Acid-Rich Lanthanide Metal-Organic Frameworks Enable Deep Proteomics with Ultratrace Biological Samples.

Label-free proteomics is widely used to identify disease mechanism and potential therapeutic targets. However, deep proteomics with ultratrace clinical specimen remains a major technical challenge due to extensive contact loss during complex sample pretreatment. Here, a hybrid of four boronic acid-rich lanthanide metal-organic frameworks (MOFs) with high protein affinity is introduced to capture proteins in ultratrace samples jointly by nitrogen-boronate complexation, cation-π and ionic interactions. A MOFs Aided Sample Preparation (MASP) workflow that shrinks sample volume and integrates lysis, protein capture, protein digestion and peptide collection steps into a single PCR tube to minimize sample loss caused by non-specific absorption, is proposed further. MASP is validated to quantify ≈1800 proteins in 10 HEK-293T cells. MASP is applied to profile cerebrospinal fluid (CSF) proteome from cerebral stroke and brain damaged patients, and identified ≈3700 proteins in 1µL CSF. MASP is further demonstrated to detect ≈9600 proteins in as few as 50µg mouse brain tissues. MASP thus enables deep, scalable, and reproducible proteome on precious clinical samples with low abundant proteins.

Label-free, background-free detection of nucleic acid with immobilization-free heterogeneous biosensor and one-pot hybridization chain reaction amplification

Although immobilization-free and label-free electrochemical DNA (E-DNA) biosensors have engaged tremendous interest due to their superior properties, such as easy operation, time-saving and cost-saving, most of them are fabricated in homogeneous modes and usually produce high background current. In the present work, we proposed a new immobilization-free and label-free heterogeneous E-DNA assay based on a dual-blocker-aided multibranched hybridization chain reaction (HCR) for one-pot nucleic acid detection with zero background. The target nucleic acid triggers the HCR involving cascaded hybridization between two metastable hairpins, resulting in the generation of HCR products with multibranched arms, which can be captured onto the electrode via π-π stacking interactions between multibranched arms and reduced graphene oxide (rGO). Prior to the incubation process with an electrode, two blockers are designed to prohibit the nonspecific absorption of unreacted hairpin probes. Thus, an immobilization-free and label-free heterogeneous electrochemical assay for one-pot nucleic acid detection with zero background is readily realized. This strategy also presents additional merits of simplicity and cheap cost, since probe immobilization, signal tag labeling, and multiple incubation processes are avoided. Therefore, the as-proposed effective and versatile biosensor has great potential to be applied in nucleic acid-related practical biosensing.

Integrating PEGylated peptide-oriented bacteria-imprinted matrix and PdPt bimetallic-doped imidazolium zeolite framework-8 for sensitive detection of Escherichia coli with smartphone readout system

Escherichia coli (E. coli) is one of the major foodborne pathogens, and its efficient isolation and detection from complex samples are crucial. Herein, we fabricated a novel hydrophilic-PEGylated peptide-oriented bacteria-imprinted PDMS matrix (HPBIM) for highly efficient capture of E. coli from complex samples. The antibody-free HPBIM possessed a hierarchical structure of imprinted cavities, which were inlaid with peptide-functionalized SiO2 (SiO2@peptide). Meanwhile, PEGylation was performed on the non-imprinted region of HPBIM to limit the non-specific absorption. So HPBIM could specifically capture target E. coli due to the synergistic effect of peptide affinity, bacteria-imprinting and PEGylation of non-imprinted region. Additionally, a new polyethylene glycol-covered / boronic acid-modified PdPt bimetallic-doped ZIF-8 (PBPPZ) was prepared for electively labeling E. coli captured by HPBIM. PBPPZ exhibited excellent peroxidase-like activity and could generate sensitive output signals, which could be further quantitatively determined by smartphone readout device. To prove the practicability, we proposed an innovative HPBIM-PBPPZ strategy, in which the HPBIM first selectively captured E. coli, then the PBPPZ specific labeled E. coli and oxidized colorless substrate into colored product, and finally the change in color was quantitatively determined by a smartphone readout device equipped with a Color Grab APP. The biomacromolecule-free HPBIM-PBPPZ strategy exhibited excellent sensitivity with limit of detection of 69 CFU mL−1 for grapefruit juice and 257 CFU mL−1 for milk, and was successfully applied in the determination of E. coli in spiked sample with recovery and relative standard deviation in the range of 88.1–106.7% and 4.0–7.8%, respectively. Therefore, we believe that the HPBIM-PBPPZ strategy has great potential to become a powerful tool for the ultrasensitive detection of pathogens in complex biological samples.

POLYMER-BASED INTERFACE TARGETING INFLAMMATION IN ULCERATIVE COLITIS

Abstract A major hurdle in the treatment of inflammatory bowel disease (IBD) is the lack of effective drug carriers that can precisely deliver the required amount of drug to the sites of inflammation. Available therapies have limited efficacy or severe side effects, largely because of the low concentration of active drugs at the disease sites and non-specific systemic absorption of the administered drugs. Drug delivery targeting the sites of intestinal inflammation offers an approach to maximize therapeutic efficacy while minimizing adverse side effects. We focus on developing formulations that can provide improved local drug administration in the treatment of ulcerative colitis (UC), one of the two main types of IBD. Targeting sites of inflammation in the gastrointestinal tract can be achieved using drug delivery systems that exploit pathophysiological features of the inflamed intestine. Our previous study showed preferential adhesion of a negatively charged small-molecule-based hydrogel to the inflamed colon in murine models of colitis and biopsies from UC patients; further, a corticosteroid drug delivered by this hydrogel demonstrated an improved efficacy compared to the drug alone. Based on our previous experience, we expanded the small-molecule-based hydrogel to polymer-based hydrogels for enhanced selective targeting. We designed the material so that it has a strong affinity towards ulcers. Through molecular structure design, we functionalized thermo-responsive poly(N-isopropylacrylamide) (PNIPAM)-based polymers to modulate the physicochemical properties of the materials and compared the resultant polymers’ gelation and adhesion to the inflamed colon in dextran sulfate sodium (DSS)-induced colitis in mice. We showed that both the types of chemical modification and polymer molecular weight affected the adhesion of the resultant hydrogels to the inflamed colon. We further quantified the disease parameters of colitis for individual mice and correlated the colitis parameters with polymers’ adhesion. Our study suggests a new strategy for targeting the inflamed colon through harnessing charge-mediated interaction and thermo-responsiveness of PNIPAM-based polymers. By adhering to the inflamed mucosa, our delivery system has the potential to maintain the drug locally at the active ulcer sites where it is needed, thereby minimizing the adverse effects of drugs on the healthy tissue. The examination of these polymeric hydrogels’ mucosal binding provides a further understanding of interactions between the polymers and the biological interface in colitis. These studies were performed in preclinical models of UC that develop colitis similar to human UC, as a prerequisite for future studies.

Novel aromatic moieties-modified poly(glycidyl amine)s with potent siRNA delivery and cancer treatment effect.

The development of safe and effective delivery systems is critical for the clinical applications of siRNA-based therapeutics. Polymer-based vectors have garnered significant attention owing to their structural flexibility and functional tunability. Polyethyleneimine (PEI) has been extensively studied for nucleic acid delivery; nevertheless, its high cytotoxicity has posed challenges for clinical applications. In this study, we have reported poly(glycidyl amine) (PGAm), a linear PEI analogue, demonstrating remarkable siRNA delivery efficacy and improved biocompatibility. By introducing three aromatic moieties (tyrosine, p-hydroxybenzenepropanoic acid, and phenylalanine) at varying ratios to further modify PGAms, we successfully constructed a library comprising 36 PGAm-based carriers. In vitro evaluations revealed that PGAm-based carriers exhibited significantly enhanced biocompatibility and reduced non-specific protein absorption in comparison to PEI25k. Among them, 10 modified PGAms achieved a knockdown of target gene expressions exceeding 80%, and 26 modified PGAms maintained over 70% cell viability when utilized for the in vitro delivery of siRNA to HeLa cells. Explorations into the structure-activity relationship of PGAm-based polyplex nanoparticles (NPs) indicated that the siRNA delivery efficacy of NPs depended on factors such as the molecular weight of PGAm precursors, the type of modifying moieties, and the modification ratio. Furthermore, it was demonstrated that two top-performing NPs, namely 2T100/siLuc and 2A50/siLuc, exhibited potent silencing of target genes in tumors following i.v. injection into mice bearing HeLa-Luc xenografts. The in vivo efficacy of the selected NPs was further validated by a remarkable anti-cancer effect when employed for the delivery of siRNA targeting polo-like kinase 1 (siPLK1) to mice with PC-3 xenograft tumors. The intravenous administration of NPs resulted in a substantial inhibition of tumor growth without significant toxicity. These findings demonstrate the feasibility of employing PGAm in siRNA delivery and provide valuable insights for the development of efficient siRNA carriers based on PGAm.

Water-stable perovskite-silica nanocomposites for encoded microbeads construction and multiplexed detection

All-inorganic lead halide perovskite nanocrystals exhibiting bright luminescence have great potential as fluorescence elements for optical encoding. However, their limited stability in water hinders the application in biosensing. In this study, novel optical encoded microbeads based on CsPbX3 (X = Cl, Br) nanocrystals are developed and applied in bead-based suspension arrays for the first time. Through the in-situ crystallization of CsPbX3 nanocrystals within mesoporous silica nano-templates (MSNs), accompanied by mesopores collapse after sintering, CsPbX3@MSNs (X3M) nanocomposites with uniform morphology and stable fluorescence intensity in aqueous solutions for up to 50 days are obtained. By assembling X3M with microspheres to form a host–guest structure, an optical encoding microbead (MX3M) library is established by varying the X3M ratio, halide composition, and the size of host microspheres, which can be easily decoded under multi-channel flow cytometer. As a result, MX3M exhibits outstanding capacity for specific target capture and negligible nonspecific absorption performance in the multiplex nucleic acid detection of respiratory viruses, with a low limit of detection (10 copies/rxn). This result highlights the tremendous potential of MX3M encoded microbeads constructed based on CsPbX3 nanocrystals for multiplexed bioassays.

Advantages of Electro-deposited Gold on Carbon Electrodes for NT-proBNP Immunosensor for Development of Heart Failure Test Kit

Accurate measurement of the N-terminal pro B-type natriuretic peptide (NT-proBNP) in serum is important for the diagnosis of heart failure (HF). Carbon screen-printed electrodes (SPCEs) modified with graphene oxide (GO) or gold (Au) were compared for the construction of NT-proBNP immunosensors. NT-proBNP and its recognition unit, a single-chain variable fragment fused with alkaline phosphatase (scFv-AP), were expressed and purified. The currents of the electrodes immobilized with scFv-AP were measured after adding an ethanolamine (ETA), blank and NT-proBNP in either phosphate buffer saline (PBS) or human serum. SPCE/Au had lower mean baseline slopes than for SPCE/GO for all measurements, in both PBS and serum, indicating greater accuracy for SPCE/Au. None of the measurements in PBS had statistically different peak currents between SPCE/GO and SPCE/Au; however, there was a significant difference with the serum. The significant reduction of SPCE/GO peak currents after applying serum blank implied non-specific absorption on the surface. The peak current of 300 pg/mL of NT-proBNP in the serum measured on SPCE/Au was significantly higher (by a factor of three) than on SPCE/GO, suggesting the possibility of using SPCE/Au to detect NT-proBNP at higher concentrations. The binding efficiency of scFv-AP to NT-proBNP did not depend on the electrodes, as shown by the similar delta peak-currents (Blank-Target). Thus, immobilized scFv-AP on SPCE/Au electrodes had good potential to accurately detect NT-proBNP in serum, for use in the fabrication of an HF test kit.

Regulating Biomolecular Surface Interactions Using Tunable Acoustic Streaming.

Diffusion limitations and nonspecific surface absorption are great challenges for developing micro-/nanoscale affinity biosensors. There are very limited approaches that can solve these issues at the same time. Here, an acoustic streaming approach enabled by a gigahertz (GHz) resonator is presented to promote mass transfer of analytes through the jet mode and biofouling removal through the shear mode, which can be switched by tuning the deviation angle, α, between the resonator and the sensor. Simulations show that the jet mode (α ≤ 0) drives the analytes in the fluid toward the sensing surface, overcomes the diffusion limitation, and enhances the binding; while the shear mode (0 < α < π/4) provides a scouring action to remove the biofouling from the sensor. Experimental studies were performed by integrating this GHz resonator with optoelectronic sensing systems, where a 34-fold enhancement for the initial binding rate was obtained. Featuring high efficiency, controllability, and versatility, we believe that this GHz acoustic streaming approach holds promise for many kinds of biosensing systems as well as lab-on-chip systems.

Hydrophilic imprinted MnO2 nanowires “coating” membrane with ultrahigh adsorption capacity for highly selective separation of Artemisinin/Artemether

The selective separation and purification of ART and ARE using molecularly imprinted membrane (MIM) has attracted considerable attention, but most of conventional blending MIM face low adsorption capacity and poor selectivity due to the blockage of imprinting sites. Herein, an alternative ART imprinted MnO2 nanowires “coating” membrane (MINM) withhydrophilicity was fabricated by vacuum filtration of imprinted MnO2 nanowires and graphene oxide nanosheets on PVDF membrane surface for selective ART separation. For the MINM, the imprinted MnO2 nanowires coating offers more available exposed imprinting sites on the MINM surface compared to that of the blending MIM, while the introduction of graphene oxide improves the hydrophilicity of MINM, significantly reducing the non-specific absorption. Consequently, the MINM exhibits ultrahigh ART adsorption capacity and selectivity, with the ART adsorption amount of 335 mg g−1 at 5 min using dynamic cross-flow separation system, about 12.18 times higher than that of ARE (27.5 mg g−1), and the separation factor (a) value of 12.39. Moreover, the ATR FT-IR dynamic spectrum discloses the in-situ formation of H-bond between ART and MINM, playing a key role in the selective adsorption process. This work provides an alternative strategy to prepare “coating” MIM for high-efficient and selective separation of complex analogue systems.

A Silicon-Based PDMS-PEG Copolymer Microfluidic Chip for Real-Time Polymerase Chain Reaction Diagnosis.

Polydimethylsiloxane (PDMS) has been widely used to make lab-on-a-chip devices, such as reactors and sensors, for biological research. Real-time nucleic acid testing is one of the main applications of PDMS microfluidic chips due to their high biocompatibility and transparency. However, the inherent hydrophobicity and excessive gas permeability of PDMS hinder its applications in many fields. This study developed a silicon-based polydimethylsiloxane-polyethylene-glycol (PDMS-PEG) copolymer microfluidic chip, the PDMS-PEG copolymer silicon chip (PPc-Si chip), for biomolecular diagnosis. By adjusting the modifier formula for PDMS, the hydrophilic switch occurred within 15 s after contact with water, resulting in only a 0.8% reduction in transmittance after modification. In addition, we evaluated the transmittance at a wide range of wavelengths from 200 nm to 1000 nm to provide a reference for its optical property study and application in optical-related devices. The improved hydrophilicity was achieved by introducing a large number of hydroxyl groups, which also resulted in excellent bonding strength of PPc-Si chips. The bonding condition was easy to achieve and time-saving. Real-time PCR tests were successfully conducted with higher efficiency and lower non-specific absorption. This chip has a high potential for a wide range of applications in point-of-care tests (POCT) and rapid disease diagnosis.

Bi-Functionalized Transferrin@MoS2-PEG Nanosheets for Improving Cellular Uptake in HepG2 Cells.

Pre-coating with a protein corona on the surface of nanomaterials (NMs) is an important strategy for reducing non-specific serum protein absorption while maintaining targeting specificity. Here, we present lipoic acid-terminated polyethylene glycol and transferrin bi-functionalized MoS2 nanosheets (Tf@MoS2-PEG NSs) as a feasible approach to enhance cellular uptake. Tf@MoS2-PEG NSs can maintain good dispersion stability in cell culture medium and effectively protect MoS2 NSs from oxidation in ambient aqueous conditions. Competitive adsorption experiments indicate that transferrin was more prone to bind MoS2 NSs than bovine serum albumin (BSA). It is noteworthy that single HepG2 cell uptake of Tf@MoS2-PEG presented a heterogeneous distribution pattern, and the cellular uptake amount spanned a broader range (from 0.4 fg to 2.4 fg). Comparatively, the intracellular Mo masses in HepG2 cells treated with BSA@MoS2-PEG and MoS2-PEG showed narrower distribution, indicating homogeneous uptake in the single HepG2 cells. Over 5% of HepG2 cells presented uptake of the Tf@MoS2-PEG over 1.2 fg of Mo, about three-fold that of BSA@MoS2-PEG (0.4 fg of Mo). Overall, this work suggests that Tf coating enhances the cellular uptake of MoS2 NSs and is a promising strategy for improving the intracellular uptake efficiency of cancer cells.

Microfluidic Engineering of Crater-Terrain Hydrogel Microparticles: Toward Novel Cell Carriers.

Fabrication and application of novel anisotropic microparticles are of wide interest. Herein, a new method for producing novel crater-terrain hydrogel microparticles is presented using a concept of droplet-aerosol impact and regional polymerization. The surface pattern of microparticles is similar to the widespread "crater" texture on the lunar surface and can be regulated by the impact morphology of aerosols on the droplet surface. Methodological applicability was demonstrated by producing ionic-cross-linked (alginate) and photo-cross-linked (poly(ethylene glycol) diacrylate, PEGDA) microparticles. Additionally, the crater-terrain microparticles (CTMs) can induce nonspecific protein absorption on their surface to acquire cell affinity, and they were exploited as cell carriers to load living cells. Cells could adhere and proliferate, and a special cellular adhesion fingerprint was observed on the novel cell carrier. Therefore, the scalable manufacturing method and biological potential make the engineered microparticles promising to open a new avenue for exploring cell-biomaterial crosstalk.

Phosphatidylserine-functionalized liposomes-in-microgels for delivering genistein to effectively treat ulcerative colitis.

Ulcerative colitis (UC) is an inflammatory disease involving ulcers in the colon and rectum. The conventional treatments for UC still have many limitations, such as non-specific release, adverse effects and low absorption, resulting in the poor bioavailability of therapeutic agents. To address these challenges, targeting delivery systems are required to specifically deliver drugs to the colonic site with controlled release. Herein, we present a novel microgel oral delivery system, loaded with liposome nanoparticles (Li NPs) containing a natural anti-inflammatory compound genistein (Gen) into alginate microgels, thereby achieving the targeted release of Gen in the colonic region and ameliorating UC symptoms. Initially, Gen was loaded into phosphatidylserine (PS)-functionalized Li NPs to form Gen@Li NPs with an average size of 245.9 ± 9.6 nm. In vitro assessments confirmed that Gen@Li NPs efficiently targeted macrophages and facilitated the internalization of Gen into cells. To prevent rapid degradation in the harsh gastrointestinal tract, Gen@Li NPs were further encapsulated into alginate microgels through electric spraying technology, forming Gen@Li microgels. In vivo distribution tests demonstrated that Gen@Li microgels possessed long-term retention in the colon and gradual release characteristics compared to Gen@Li NPs. Furthermore, in vivo experiments confirmed that Gen@Li microgels significantly alleviated UC symptoms in mice induced by dextran sulfate sodium salt (DSS) mainly through reducing the expression levels of pro-inflammatory cytokines (TNF-α, IL-1β and IL-6) and promoting colonic mucosal barrier repair through upregulation of mucosal protein expression. This study shed light on the potential of utilizing oral administration of natural compounds for UC treatment.

Topological insulator Bi2Se3 based electrochemical aptasensors for the application of sensitive detection of interferon-γ.

Interferon-γ (IFN-γ) is one of the crucial inflammatory cytokines as an early indicator of multiple diseases. A fast, simple, sensitive and reliable IFN-γ detection method is valuable for early diagnosis and monitoring of treatment. In this work, we creatively developed an electrochemical aptasensor based on the topological material Bi2Se3 for sensitive IFN-γ quantification. The high-quality Bi2Se3 sheet was directly exfoliated from a single crystal, which immobilized the synthesized IFN-γ aptamer. Under optimal conditions, the electrochemical signal revealed a wide linear relation along with the logarithmic concentration of IFN-γ from 1.0 pg mL-1 to 100.0 ng mL-1, with the limit of detection as low as 0.5 pg mL-1. The topological material Bi2Se3 with Dirac surface states improved the electrochemical signal/noise ratio and thus the sensitivity of the sensors. Furthermore, this electrochemical aptasensor exhibited excellent specificity and stability, which could be attributed to the large-scale smooth surface of the Bi2Se3 sheet with few defects decreasing the non-specific absorption. The developed biosensor has the same good performance as the ELISA method for detecting the real serum samples. Our work demonstrates that the developed electrochemical aptasensors based on topological materials have great potential in the field of clinical determination.

Tunable graphene oxide for the low-fouling electrochemical sensing of uric acid in human serum.

Numerous studies have been reported to improve the selectivity of uric acid (UA) by eliminating the interference from other electroactive species that coexist in biological fluids. However, two main challenges associated with the nonenzymatic electrochemical detection of UA need to be overcome to achieve practical applications in biological samples. Those are the chemical fouling of electrodes caused by the oxidation product of UA and biofouling due to the non-specific absorption of biological macromolecules. It was found that the residual oxo-functional groups and defects on graphene played a crucial part in both electrocatalysis and anti-biofouling. Here, graphene oxide (GO) was tuned by electro-oxidation and electro-reduction and was investigated in antifouling and electrocatalytic performances for the electrochemical sensing of UA by using pristine GO, BSA bound GO, electro-reduction-treated GO and electro-oxidation-treated GO. The electro-oxidation-treated GO was explored in electrochemical sensing for the first time and exhibited the highest sensitivity and low fouling properties. Holey GO might be formed on the electrode surface by the electrochemical oxidation method in a mild and green solution without the use of an acid. The different electrode interfaces as well as the interaction with BSA were investigated by Raman spectroscopy, X-ray photoelectron spectroscopy, contact angle measurements, scanning electron microscopy, electrochemistry, and electrochemical impedance spectroscopy.

In Situ Electrochemical Formation of Oxo-Functionalized Graphene on Glassy Carbon Electrode with Chemical Fouling Recovery and Antibiofouling Properties for Electrochemical Sensing of Reduced Glutathione.

Electrochemical detection can be used to achieve intracellular or in vivo analysis of reduced glutathione (GSH) in tissues such as brain by using a microelectrode, which can help to better understand the complex biochemical processes of this molecule in the human body. The main challenges associated with electrochemical GSH detection are the chemical fouling of electrodes, caused by the oxidation product of GSSG, and biofouling due to the non-specific absorption of biological macromolecules. Oxo-functionalized graphene was generated in situ on the surface of a glassy carbon electrode using a green electrochemical method without using any other modifiers or materials in a mild water solution. The fabricated oxo-functionalized graphene interface was characterized by Raman spectroscopy, X-ray photoelectron spectroscopy, electrochemistry, electrochemical impedance spectroscopy, and contact angle measurements. The interface showed high electrocatalytic activity towards the oxidation of GSH, and a simple and efficient GSH sensor was developed. Interestingly, the electrode is reusable and could be recovered from the chemical fouling via electrochemical oxidation and reduction treatment. The electrode also exhibited good antibiofouling properties. The presented method could be a promising method used to treat carbon materials, especially carbon-based microelectrodes for electrochemical monitoring of intracellular glutathione or in vivo analysis.

Mannosylated Systems for Targeted Delivery of Antibacterial Drugs to Activated Macrophages.

Macrophages are a promising target for drug delivery to influence macrophage-associated processes in the body, namely due to the presence of resistant microorganisms in macrophages. In this work, a series of mannosylated carriers based on mannan, polyethylenimine (PEI) and cyclodextrin (CD) was synthesized. The molecular architecture was studied using FTIR and 1H NMR spectroscopy. The particle size, from small 10-50 nm to large 500 nm, depending on the type of carrier, is potentially applicable for the creation of various medicinal forms: intravenous, oral and inhalation. Non-specific capture by cells with a simultaneous increase in selectivity to CD206+ macrophages was achieved. ConA was used as a model mannose receptor, binding galactosylated (CD206 non-specific) carriers with constants of the order of 104 M-1 and mannosylated conjugates of 106-107 M-1. The results of such primary "ConA-screening" of ligands are in a good agreement in terms of the comparative effectiveness of the interaction of ligands with the CD206+ macrophages: non-specific (up to 10%) absorption of highly charged and small particles; weakly specific uptake of galactosylated polymers (up to 50%); and high affine capture (more than 70-80%) of the ligands with grafted trimannoside was demonstrated using the cytometry method. Double and multi-complexes of antibacterials (moxifloxacin with its adjuvants from the class of terpenoids) were proposed as enhanced forms against resistant pathogens. In vivo pharmacokinetic experiments have shown that polymeric carriers significantly improve the efficiency of the antibiotic: the half-life of moxifloxacin is increased by 2-3 times in conjugate-loaded forms, bio-distribution to the lungs in the first hours after administration of the drug is noticeably greater, and, after 4 h of observation, free moxifloxacin was practically removed from the lungs of rats. Although, in polymer systems, its content is significant-1.2 µg/g. Moreover, the importance of the covalent crosslinking carrier with mannose label was demonstrated. Thus, this paper describes experimental, scientifically based methods of targeted drug delivery to macrophages to create enhanced medicinal forms.