Polyaniline-based bovine serum albumin imprinted electrochemical sensor for ultra-trace-level detection in clinical and food safety applications

Monitoring bovine serum albumin (BSA) at ultra-low levels is crucial for clinical and food safety applications, as it plays a significant role in identifying various health conditions and potential risks, necessitating fast, trace-level detection of BSA. This study proposes an approach to address these challenges by employing molecularly imprinted polymer (MIP) to develop an ultra-trace-level and cost-effective BSA sensing platform. The MIP electrochemical sensor was developed using polyaniline (PANI) combined with the protein crosslinker glutaraldehyde (GA) to optimize BSA surface imprinting in the MIP. As a result, the sensor achieves a sensitivity of 1.24 μA/log(pg/mL), with a picomolar detectable limit of 2.3 pg/mL (0.035 pM) and a wide detection range from 20 pg/mL to 200,000 pg/mL (0.303 pM to 3030 pM), making it suitable for clinical and food safety applications. Additionally, the study explores the interaction between an acidic surfactant protein eluent (acetic acid with sodium dodecyl sulfate, AcOH-SDS) and BSA vacant sites, enhancing recognition and re-binding. The PANI-based MIP sensor demonstrates initial feasibility and practicality in commercial milk and real human serum, opening avenues for early disease detection and ensuring food safety in BSA-related immune responses.

Sensing with Molecularly Imprinted Membranes on Two-Dimensional Solid-Supported Substrates

Molecularly imprinted membranes (MIMs) have been a focal research interest since 1990, representing a breakthrough in the integration of target molecules into membrane structures for cutting-edge sensing applications. This paper traces the developmental history of MIMs, elucidating the diverse methodologies employed in their preparation and characterization on two-dimensional solid-supported substrates. We then explore the principles and diverse applications of MIMs, particularly in the context of emerging technologies encompassing electrochemistry, surface-enhanced Raman scattering (SERS), surface plasmon resonance (SPR), and the quartz crystal microbalance (QCM). Furthermore, we shed light on the unique features of ion-sensitive field-effect transistor (ISFET) biosensors that rely on MIMs, with the notable advancements and challenges of point-of-care biochemical sensors highlighted. By providing a comprehensive overview of the latest innovations and future trajectories, this paper aims to inspire further exploration and progress in the field of MIM-driven sensing technologies.

Current methods and prospects of coronavirus detection

SARS-COV-2 is a novel coronavirus discovered in Wuhan in December 30, 2019, and is a family of SARS-COV (severe acute respiratory syndrome coronavirus), that is, coronavirus family. After infection with SARS-COV-2, patients often experience fever, cough, gas prostration, dyspnea and other symptoms, which can lead to severe acute respiratory syndrome (SARS), kidney failure and even death. The SARS-COV-2 virus is particularly infectious and has led to a global infection crisis, with an explosion in the number of infections. Therefore, rapid and accurate detection of the virus plays a vital role. At present, many detection methods are limited in their wide application due to their defects such as high preparation cost, poor stability and complex operation process. Moreover, some methods need to be operated by professional medical staff, which can easily lead to infection. In order to overcome these problems, a Surface molecular imprinting technology (SM-MIT) is proposed for the first time to detect SARS-COV-2 virus. For this SM-MIT method, this review provides detailed detection principles and steps. In addition, this method not only has the advantages of low cost, high stability and good specificity, but also can detect whether it is infected at designated points. Therefore, we think SM-MIT may have great potential in the detection of SARS-COV-2 virus.

Creation of glycoprotein imprinted self-assembled monolayers with dynamic boronate recognition sites and imprinted cavities for selective glycoprotein recognition

Glycoproteins are involved in the pathogenesis and development of many diseases and are used as biomarkers for disease diagnosis. It is highly desirable to develop highly sensitive and selective methods for the detection of glycoproteins without the use of antibodies. Imprinting of proteins represents one of the most challenging tasks. Glycoprotein imprinted self-assembled monolayers (SAMs) were created, for the first time, from an oligo(ethylene glycol) (OEG) terminated 1,2-dithiolane derivative linked through an alkyl chain incorporated with two amide groups (DHAP) and combined functional thiols of p-mercaptophenylboronic acid (PMBA) and p-aminothiophenol (PATP) in aqueous media, without the use of polymerization initiators. Combined action of PMBA and PATP was essential for the development of boronate recognition sites for glycoproteins at the physiological pH, attributed to the water molecule-mediated Lewis acid-base interactions between the electron-deficient PMBA and the electron-rich PATP. DHAP played key roles not only in cementation of imprinted cavities by means of double hydrogen bond networks through the amide groups but also in resistance to nonspecific protein binding by terminal OEG moieties, as well as hydrogen bond binding sites from the amide groups exposed to imprinted cavities. The created glycoprotein imprinted SAMs showed excellent recognition selectivity of target glycoproteins. The strategy for tailor-made glycoprotein imprinted SAMs explores a new avenue to the creation of intelligent biomaterials and fabrication of chemosensors.

An efficient ICT-based ratio/colorimetric tripodal azobenzene probe for the recognition/discrimination of F-, AcO- and H2PO4- anions

The tripodal probe L was readily prepared via introducing rhodamine and azobenzene groups in a two-step procedure. Studies of the recognition properties indicated that probe L exhibited high sensitivity and selectivity towards F^-, AcO^- and H₂PO₄^- through a ratiometric colorimetric response with low detection limits of the order of 10^-7 M. The complexation behaviour was fully investigated by spectral titration, ¹H NMR spectroscopic titration and mass spectrometry. Probe L not only recognizes F^-, AcO^- and H₂PO₄^-, but can also distinguish between these three anions via the different ratiometric behaviour in their UV-vis spectra (387/505 nm for L-H₂PO₄^-, 387/530 nm for L-AcO^- and 387/575 nm for L-F^- complex) or via different colour changes (light coral for L-H₂PO₄^-, light pink for L-AcO^- and violet for the L-F^- complex). Additionally, given the presence of NH and OH groups in probe L, which can be protonated and deprotonated, probe L further exhibited an excellent pH response over a wide pH range (pH 3 to pH 12).

Design and synthesis of supramolecular functional monomers bearing urea and norbornene motifs

Three sets of functional monomers namely urea-based, 2-ureido-4[1H]-primidone (UPy)-based and norbornene based functional monomers were designed and synthesized. These functional monomers (FM) were obtained in decent yields using amine and isocyanate/norbornene as starting materials. Methacrylate and styrene isocyanate with 1,4-diaminobutane/tris(2-aminoethyl)amine were chosen for the synthesis of symmetrical, asymmetrical and three-branched urea-functional monomers, respectively. UPy-based FMs were synthesized with isocyanate and 2-amino-4-hydroxy-6-methylpyrimidine. The synthesis of these monomers feature short reaction times, mild reaction conditions and no need for column chromatographic purification. Furthermore, the norbornene based FM was used for preparing molecularly imprinted polymers (MIPs) by Ring-Opening Metathesis Polymerization (ROMP). Results showed that these synthetic routes represent a convenient and useful approach for synthesis of novel functional monomers.

A chip-based potentiometric sensor for a Zika virus diagnostic using 3D surface molecular imprinting

The latest Zika virus (ZIKV) pandemic caused great international concern from explosively proliferating throughout the Americas. Currently, there is no vaccine to prevent Zika virus infection and available tests rely on antibodies or RNA. Unfortunately, antibody-based detection systems can result in false positive results and RNA-based detection systems are costly, time-consuming, and impractical for testing in remote regions. In this study, a potential point-of-care (POC) diagnostic system was developed using a chip-based potentiometric sensor to detect Zika virus using a 3D molecular imprinting technique. This chip-based potentiometric sensor system was able to detect 10^-1 PFU mL^-1 ZIKV in a buffered solution under 20 minutes without any sample manipulation. This sensor was tested against Dengue virus at clinical viral loads and showed no sign of cross-reactivity. When tested against human saliva samples containing clinical viral loads, this sensor was able to detect 10 PFU mL^-1 ZIKV among the pool of bio-macromolecules. The high sensitivity and high selectivity demonstrated here proved that this lab-on-a-chip diagnostic has the potential to become a POC detection system for rapid and accurate screening of flaviviruses.

ation of the igh ensitiv Label-Free

A highly sensitive electrochemical biosensor with a signal amplification platform of electrodeposited gold nanoparticle (AuNP) has been developed and characterized. The sizes of the synthesized AuNP were found to be critical for the performance of biosensor in which the sizes were dependent on HAuCl₄ and acid concentrations; as well as on scan cycles and scan rates in the gold electro-reduction step. Systematic investigations of the adsorption of proteins with different sizes from aqueous electrolyte solution onto the electrodeposited AuNP surface were performed with a potentiometric method and calibrated by design of experiment (DOE). The resulting amperometric glucose biosensors was demonstrated to have a low detection limit (> 50M) and a wide linear range after optimization with AuNP electrodeposition.

HPLC determination of γ-aminobutyric acid and its analogs in human serum using precolumn fluorescence labeling with 4-(carbazole-9-yl)-benzyl chloroformate

In this study, a simple analytical method for the determination of γ-aminobutyric acid, gabapentin, and baclofen by using high-performance liquid chromatography with fluorescence detection was developed. An amidogen-reactive fluorescence labeling reagent, 4-(carbazole-9-yl)-benzyl chloroformate was first used to sensitively label these analytes. The completed labeling of these analytes can be finished rapidly only within 5 min at the room temperature (25°C) to form 4-(carbazole-9-yl)-benzyl chloroformate labeled fluorescence derivatives. These labeled derivatives expressed strong fluorescence property with the maximum excitation and emission wavelengths of 280 and 380 nm, respectively. The labeled derivatives were analyzed using a reversed-phase Eclipse SB-C18 column within 10 min with satisfactory shapes. Excellent linearity (R²  > 0.995) for all analytes was achieved with the limits of detection and the limits of quantitation in the range of 0.25-0.35 and 0.70-1.10 μg/L, respectively. The proposed method was used for the simultaneous determination of γ-aminobutyric acid and its analogs in human serum with satisfactory recoveries in the range of 94.5-97.5%.

Carboplatin prodrug conjugated Fe3O4 nanoparticles for magnetically targeted drug delivery in ovarian cancer cells

The magnetically targeted NPs@carboplatin can act as a drug delivery system and will have great potential in ovarian cancer therapeutic applications.

The influence of roughness on stem cell differentiation using 3D printed polylactic acid scaffolds

With the increase in popularity of 3D printing, an important question arises as to the equivalence between devices manufactured by standard methods vs. those presenting with identical bulk specifications, but manufactured via fused deposition modeling (FDM) printing. Using thermal imaging in conjunction with electron and atomic force microscopy, we demonstrate that large thermal gradients, whose distribution is difficult to predict, are associated with FDM printing and result in incomplete fusion and sharkskin of the printing filament. Even though these features are micro or submicron scale, and hence may not interfere with the intended function of the device, they can have a profound influence if the device comes in contact with living tissue. Dental pulp stem cells were cultured on substrates of identical dimensions, which were either printed or molded from the same PLA stock material. The cultures exhibited significant differences in plating efficiency, migration trajectory, and morphology at early times stemming from attempts by the cells to minimize cytoplasm deformation as they attempt to adhere on the printed surfaces. Even though biomineralization without dexamethasone induction was observed in all cultures at later times, different gene expression patterns were observed on the two surfaces. (Osteogenic markers were upregulated on molded substrates, while odontogenic markers were upregulated on the FDM printed surfaces.) Our results clearly indicate that the method of manufacturing is an important consideration in comparing devices, which come in contact with living tissues.

A bisulfite treatment and PCR-free global DNA methylation detection method using electrochemical enzymatic signal engagement

In this paper we report on a bisulfite treatment and PCR amplification-free method for sensitive and selective quantifying of global DNA methylation. Our method utilizes a three-step strategy that involves (i) initial isolation and denaturation of global DNA using the standard isolation protocol and direct adsorption onto a bare gold electrode via gold-DNA affinity interaction, (ii) selective interrogation of methylation sites in adsorbed DNA via methylation-specific 5mC antibody, and (iii) subsequent signal enhancement using an electrochemical-enzymatic redox cycling reaction. In the redox cycling reaction, glucose oxidase (GO_x) is used as an enzyme label, glucose as a substrate and ruthenium complex as a redox mediator. We initially investigated the enzymatic properties of GO_x by varying glucose and ruthenium concentration to delineate the redox cyclic mechanism of our assay. Because of the fast electron transfer by ruthenium (Ru) complex and intrinsic signal amplification from GO_x label, this method could detect as low as 5% methylation level in 50 ng of total DNA input. Moreover, the use of methylation-specific 5mC antibody conjugated GO_x makes this assay relatively highly selective for DNA methylation analysis. The data obtained from the electrochemical response for different levels of methylation showed excellent interassay reproducibility of RSD (relative standard deviation) < 5% for n = 3. We believe that this inexpensive, rapid, and sensitive assay will find high relevance as an alternative method for DNA methylation analysis both in research and clinical platforms.

Molecular Fingerprints of Hemoglobin on a Nanofilm Chip

Hemoglobin is an iron carrying protein in erythrocytes and also an essential element to transfer oxygen from the lungs to the tissues. Abnormalities in hemoglobin concentration are closely correlated with health status and many diseases, including thalassemia, anemia, leukemia, heart disease, and excessive loss of blood. Particularly in resource-constrained settings existing blood analyzers are not readily applicable due to the need for high-level instrumentation and skilled personnel, thereby inexpensive, easy-to-use, and reliable detection methods are needed. Herein, a molecular fingerprints of hemoglobin on a nanofilm chip was obtained for real-time, sensitive, and selective hemoglobin detection using a surface plasmon resonance system. Briefly, through the photopolymerization technique, a template (hemoglobin) was imprinted on a monomeric (acrylamide) nanofilm on-chip using a cross-linker (methylenebisacrylamide) and an initiator-activator pair (ammonium persulfate-tetramethylethylenediamine). The molecularly imprinted nanofilm on-chip was characterized by atomic force microscopy and ellipsometry, followed by benchmarking detection performance of hemoglobin concentrations from 0.0005 mg mL⁻¹ to 1.0 mg mL⁻¹. Theoretical calculations and real-time detection implied that the molecularly imprinted nanofilm on-chip was able to detect as little as 0.00035 mg mL⁻¹ of hemoglobin. In addition, the experimental results of hemoglobin detection on the chip well-fitted with the Langmuir adsorption isotherm model with high correlation coefficient (0.99) and association and dissociation coefficients (39.1 mL mg⁻¹ and 0.03 mg mL⁻¹) suggesting a monolayer binding characteristic. Assessments on selectivity, reusability and storage stability indicated that the presented chip is an alternative approach to current hemoglobin-targeted assays in low-resource regions, as well as antibody-based detection procedures in the field. In the future, this molecularly imprinted nanofilm on-chip can easily be integrated with portable plasmonic detectors, improving its access to these regions, as well as it can be tailored to detect other proteins and biomarkers.

Poly(Ethylene Glycol)-Polylactide Micelles for Cancer Therapy

For the treatment of malignancy, many therapeutic agents, including small molecules, photosensitizers, immunomodulators, proteins and genes, and so forth, have been loaded into nanocarriers for controllable cancer therapy. Among these nanocarriers, polymeric micelles have been considered as one of the most promising nanocarriers, some of which have already been applied in different stages of clinical trials. The successful advantages of polymeric micelles from bench to bedside are due to their special core/shell structures, which can carry specific drugs in certain disease conditions. Particularly, poly(ethylene glycol)–polylactide (PEG–PLA) micelles have been considered as one of the most promising platforms for drug delivery. The PEG shell effectively prevents the adsorption of proteins and phagocytes, thereby evidently extending the blood circulation period. Meanwhile, the hydrophobic PLA core can effectively encapsulate many therapeutic agents. This review summarizes recent advances in PEG–PLA micelles for the treatment of malignancy. In addition, future perspectives for the development of PEG–PLA micelles as drug delivery systems are also presented.

One-pot synthesis of highly fluorescent Fe2+-doped carbon dots for a dual-emissive nanohybrid for the detection of zinc ions and histidine

Fe²⁺ was confirmed to be the only definitive one of the common metal ions to synthesize the highly fluorescent carbon dots with proline as the carbon resource at 80 °C for visual fluorescence sensing Zn2+ and histidine, respectively.

Size-controllable dual drug-loaded silk fibroin nanospheres through a facile formation process

Paclitaxel/doxorubicin-loaded silk fibroin nanospheres were prepared through a facile and green method and showed a synergistic effect on the anti-proliferative activity.

Rapid fluorescence immunoassay of benzo[a]pyrene in mainstream cigarette smoke based on a dual-functional antibody–DNA conjugate

Benzo[a]pyrene (BaP) is considered as one of the most carcinogenic pollutants in cigarette smoke. The development of simple and sensitive BaP screening methods can help assess the risk of cigarette exposure to the human body rapidly. In this report, a rapid fluorescence immunoassay (RFIA) method for the detection of BaP is proposed, the core of which is the synthesis of bifunctional covalent antibody–DNA conjugates for target recognition and signal amplification. Based on the optimization of the SYBR Green I and PAH–BSA concentrations, as well as DNA–antibody immune complex's dilution in the RFIA system, a serial dilution of BaP was tested with this method. The results showed that the linear working range of the RFIA for BaP is 0.46 to 333 ng mL⁻¹, which is much wider than traditional ELISA. The detection limit was 0.32 ng mL⁻¹, which was more sensitive than other methods such as the redox-labeled electrochemical immunoassay method and the competitive piezoelectric biosensor. Then the cross-reactions (CR) of other PAHs in cigarette smoke were evaluated using this RFIA and found that the cross-reactions of naphthalene, anthracene, and pyrene were very low (<1%). The cross-reaction in this RFIA system can be reduced by improving the specificity of the antibody. To the best of our knowledge, this is the first time that the BaP in mainstream cigarette smoke was tested; the RFIA demonstrates fast and simple experimental manipulations and better working curves and sensitivity.

Benzo[a]pyrene (BaP) is considered as one of the most carcinogenic pollutants in cigarette smoke.

A highly selective TPE-based AIE fluorescent probe is developed for the detection of Ag+

The detection of Ag⁺ in the environment is very important to determine the level of pollution from silver complexes, which have caused various human health problems. Herein, an aggregation-induced emission (AIE) chromophore (tetraphenylethane, TPE) attached to a benzimidazole group (tetra-benzimidazole, TBI–TPE) is synthesized and utilized to detect Ag⁺ in the environment. The strong chelating effect between the benzimidazole group and Ag⁺ leads to the formation of aggregates, and strong yellow fluorescence signals were observed after adding Ag⁺ into a TBI–TPE solution. The stoichiometry of the complex of TBI–TPE and Ag⁺ was established to be 1 : 2 using photochemical and mass spectra measurements. The detection limit of the Ag⁺ assay is 90 nM with a linear range from 100 nM to 6 μM. This study provides a facile method to determine Ag⁺ in real environmental samples with satisfactory results.

We develop a highly selective TPE-based AIE fluorescent probe containing a benzimidazole group for the detection of Ag⁺.

Microfabricated passive resonator biochip for sensitive radiofrequency detection and characterization of glucose

Passive sensors provide a new route for the characterization of concentration-dependent radiofrequency parameters with high reproducibility in real time. We propose a microfabricated resonator realized using integrated passive device technology for the sensitive detection and characterization of glucose. Experimental results verify the high performance of the proposed biosensor, because radiofrequency parameters such as resonance frequency (from 0.541 to 1.05 GHz) and reflection coefficient (from −34.04 to −24.11 dB) linearly vary in response to deionized water and subsequent iterative measurements of different glucose concentrations (from 50 to 250 mg dL⁻¹). The biosensor has a very low limit of detection of 8.46 mg dL⁻¹, a limit of quantitation of 25.63 mg dL⁻¹, a minimum frequency sensitivity of 29 MHz, and a minimum magnitude sensitivity of 0.22 dB. Moreover, the coupling coefficient consistently decreases with the increasing glucose concentration. We also used the measured radiofrequency parameters to determine the unknown permittivity of glucose samples through mathematical modeling. A decreasing trend in the loss tangent and an increasing trend in the characteristic wave impedance were observed with the increase of glucose concentration. The reproducibility of the sensor was verified through iterative measurements on the same sensor surface and subsequent study of surface morphology.

Passive sensors provide a new route for the characterization of concentration-dependent radiofrequency parameters with high reproducibility in real time.

Smart multifunctional polyurethane microcapsules for the quick release of anticancer drugs in BGC 823 and HeLa tumor cells

Smart multifunctional drug delivery systems (DDSs) based on cytophilic fluorescent polyurethane copolymer microcapsules with high tumor cell internalization, triggered release, quick cancer cell death and real time fluorescent monitoring abilities is developed as a facile and versatile approach for precision cancer therapy.

Targeting thyroid cancer with acid-triggered release of doxorubicin from silicon dioxide nanoparticles

Currently, therapy for thyroid cancer mainly involves surgery and radioiodine therapy. However, chemotherapy can be used in advanced and aggressive thyroid cancer that cannot be treated by other options. Nevertheless, a major obstacle to the successful treatment of thyroid cancer is the delivery of drugs to the thyroid gland. Here, we present an example of the construction of silicon dioxide nanoparticles with thyroid–stimulating-hormone receptor-targeting ligand that can specifically target the thyroid cancer. Doxorubicin nanoparticles can be triggered by acid to release the drug payload for cancer therapy. These nanoparticles shrink the tumor size in vivo with less toxic side effects. This research paves the way toward effective chemotherapy for thyroid cancer.

The influence of surface chemistry on adsorbed fibrinogen conformation, orientation, fiber formation and platelet adhesion

Thrombosis is a clear risk when any foreign material is in contact with the bloodstream. Here we propose an immunohistological stain-based model for non-enzymatic clot formation that enables a facile screen for the thrombogenicity of blood-contacting materials. We exposed polymers with different surface chemistries to protease-free human fibrinogen. We observed that on hydrophilic surfaces, fibrinogen is adsorbed via αC regions, while the γ400-411 platelet-binding dodecapeptide on the D region becomes exposed, and fibrinogen fibers do not form. In contrast, fibrinogen is adsorbed on hydrophobic surfaces via the relatively hydrophobic D and E regions, exposing the αC regions while rendering the γ400-411 inaccessible. Fibrinogen adsorbed on hydrophobic surfaces is thus able to recruit other fibrinogen molecules through αC regions and polymerize into large fibrinogen fibers, similar to those formed in vivo in the presence of thrombin. Moreover, the γ400-411 is available only on the large fibers not elsewhere throughout the hydrophobic surface after fibrinogen fiber formation. When these surfaces were exposed to gel-sieved platelets or platelet rich plasma, a uniform monolayer of platelets, which appeared to be activated, was observed on the hydrophilic surfaces. In contrast, large agglomerates of platelets were clustered on fibers on the hydrophobic surfaces, resembling small nucleating thrombi. Endothelial cells were also able to adhere to the monomeric coating of fibrinogen on hydrophobic surfaces. These observations reveal that the extent and type of fibrinogen adsorption, as well as the propensity of adsorbed fibrinogen to bind platelets, may be modulated by careful selection of surface chemistry.

STATEMENTS OF SIGNIFICANCE

Thrombosis is a well-known side effect of the introduction of foreign materials into the bloodstream, as might exist in medical devices including but not limited to stents, valves, and intravascular catheters. Despite many reported studies, the body's response to foreign materials in contact with the blood remains poorly understood. Current preventive methods consist of drug eluting coatings on the devices or the systemic administration of standard anticoagulants. Here we present a potential mechanism by which surface chemistry can affects fibrinogen conformation and thus affects platelet adhesion and consequently thrombus formation. Our findings suggest a possible coating which enables endothelial cell adhesion while preventing platelet adhesion.

The assembly of small molecule conjugate amphiphiles into a precise nanomedicine for colon cancer

A small molecule conjugate based on a traditional Chinese medicine cantharidin (CTR), which is an anhydride, and the anticancer drug camptothecin (CPT) was designed.

Manipulation of cell adhesion and dynamics using RGD functionalized polymers

An ABA tri-block co-polymer with RGD peptide sequences inserted were synthesized. Cell adhesion can be controlled by polymer configuration changing via electrical field.