Study on Drug Resistance to Treatment for Ureaplasma Urealyticum Infections in the Female Genital Tract.

BACKGROUND: Ureaplasma urealyticum (U. urealyticum) commonly occurs in female genitourinary infections, and its different biovars and serotypes have varying degrees of resistance to different antibiotics. This study aimed to ex-plore the characteristics of U. urealyticum infection and drug-resistant profiles in Chinese females. METHODS: We included 1,045 females with genital tract infections who visited Tangshan Workers' Hospital and Tangshan Maternal and Child Health Center from September 2017 to December 2018. The bacteria were selectively cultured, and drug sensitivity experiments were conducted. Eight pairs of oligonucleotide primers were designed, and polymerase chain reaction (PCR) was performed to amplify specific DNA fragments to perform bacterial strain typing. RESULTS: Among the 1,045 participants included, 566 (54.11%) participants were positive for mycoplasma infection. There were 432 (41.34%) participants with U. urealyticum infection, accounting for 76.33% of the positive participants. The infection rate of U. urealyticum was the highest in females who were 21 - 30 years old, followed by those who were 31 - 40 years old. Ureaplasma urealyticum showed the highest sensitivity to tetracyclines and the greatest resistance to quinolones. The biovar 1 of U. urealyticum with the highest detection rate of serotype 4, accounted for 66.88%. The biovar 2 of U. urealyticum mainly showed mixed subtypes 2 and 3. Biovar 2 showed higher resistance to sparfloxacin, clarithromycin, josamycin, and doxycycline than biovar 1. CONCLUSIONS: Women might be more susceptible to U. urealyticum, especially if they are of childbearing age. Urea-plasma urealyticum is mainly caused by a single serotype 6 infection. The resistance of U. urealyticum to quinolone (e.g., norfloxacin) is a great concern. Sparfloxacin, clarithromycin, ciprofloxacin, and doxycycline might be more suitable for people with biovar 1 infection. Biotyping may facilitate clinical drug use and help avoid the emergence of drug-resistant strains.

CYSLTR1 antagonist inhibits Th17 cell differentiation by regulating the NF-κB signaling for the treatment of psoriasis.

Cysteinyl leukotriene receptor 1 (CYSLTR1) is observed to increase in psoriatic skin lesions. Montelukast, a CYSLTR1 antagonist, effectively treats inflammatory disorders, such as rheumatoid arthritis, multiple sclerosis, and atopic dermatitis. Thus, blocking CYSLTR1 may be a promising strategy for psoriasis immunotherapy. We prepared a montelukast sodium cream and solution and investigated their effects on psoriasis-like skin lesions induced by imiquimod (IMQ). After the treatment, serum, skin, and spleen samples were collected for evaluation. We treated human T helper (Th) 17 cells with montelukast in vitro to study its effect on Th17 differentiation and nuclear factor kappa-B (NF-κB) signaling. We also created a keratinocyte proliferation model induced by M5 cytokines and assessed the influence of montelukast on key psoriasis-related genes. We induced psoriasis in CYSLTR1 knockout (KO) mice using IMQ to explore the role of CYSLTR1 in psoriasis development. Montelukast sodium cream and solution effectively reduced the psoriasis area and severity index (PASI) and alleviated disease symptoms in IMQ-induced mice. Furthermore, reduced infiltration of inflammatory cells (Th1, Th17, and T follicular helper [Tfh] cells), decreased mRNA expression of cytokines in the skin (interleukin [IL]-17/F and IL-23), and lower serum concentrations of various cytokines (IL-2, IL-6, IL-13, and IL-17A/F) were observed. Montelukast cream and solution also decreased spleen size and the proportion of Th17 and Tfh cells, and significantly inhibited NF-κB signaling-related genes after application. Moreover, montelukast inhibited Th17 cell differentiation and suppressed NF-κB signaling in vitro. CYSLTR1 KO mice induced with IMQ showed improvement in PASI scores, serum IL-17A/F levels, and lower Th1 and Th17 cells in the spleen and skin compared to wild-type mice. Montelukast also suppressed the proliferation and inflammatory response of keratinocytes by regulating NF-κB signaling. Collectively, our results strongly indicate that inhibition of CYSLTR1 signaling to target the Th17 response holds significant promise as a therapeutic approach to manage psoriasis.

A machine vision-assisted Argonaute-mediated fluorescence biosensor for the detection of viable Salmonella in food without convoluted DNA extraction and amplification procedures.

The precise identification viable pathogens hold paramount significance in the prevention of foodborne diseases outbreaks. In this study, we integrated machine vision and learning with single microsphere to develop a phage and Clostridium butyricum Argonaute (CbAgo)-mediated fluorescence biosensor for detecting viable Salmonella typhimurium (S. typhimurium) without convoluted DNA extraction and amplification procedures. Phage and lysis buffer was utilized to capture and lyse viable S. typhimurium, respectively. Subsequently, CbAgo can cleave the bacterial DNA to obtain target DNA that guides a newly targeted cleavage of fluorescent probes. After that, the resulting fluorescent signal accumulates on the streptavidin-modified single microsphere. The overall detection process is then analyzed and interpreted by machine vision and learning algorithms, achieving highly sensitive detection of S. typhimurium with a limit of detection at 40.5 CFU/mL and a linear range of 50-107 CFU/mL. Furthermore, the proposed biosensor demonstrates standard recovery rates and coefficients of variation at 93.22% - 106.02% and 1.47% - 12.75%, respectively. This biosensor exhibits exceptional sensitivity and selectivity, presenting a promising method for the rapid and effective detection of foodborne pathogens. ENVIRONMENTAL IMPLICATION: Bacterial pathogens exist widely in the environment and seriously threaten the safety of human life. In this study, we developed a phage and Clostridium butyricum Argonaute-mediated fluorescence biosensor for the detection of viable Salmonella typhimurium in environmental water and food samples. Compared with other Salmonella detection methods, this method does not need complex DNA extraction and amplification steps, which reduces the use of chemical reagents and experimental consumables in classic DNA extraction kit methods.

Cu(II)-induced magnetic resonance tuning and enhanced magnetic relaxation switching immunosensor for sensitive detection of chlorpyrifos and Salmonella.

Magnetic relaxation switching (MRS) biosensors have been recognized as useful analytical tools for a range of targets; however, traditional MRS biosensors are limited by the "prozone effect", resulting in a narrow linear range and low sensitivity. Herein, we proposed a paramagnetic Cu2+-induced magnetic resonance tuning (MRET) strategy, based on which Cu2+ ions and magnetic nanoparticles (MNPs) were adopted to construct a Cu-MNP-mediated MRS (Cu-M-MRS) immunosensor with Cu2+ ions acting as a quencher and MNPs as an enhancer. An Fe3O4@polydopamine-secondary antibody conjugate was prepared and used to correlate the amount of Cu2+ ions to the target concentration through an immunoassay. Based on the immunoreaction, the Cu-M-MRS immunosensor enabled the sensitive detection of chlorpyrifos (0.05 ng/mL, a 77-fold enhancement in sensitivity compared with the traditional MRS immunosensor) and Salmonella (50 CFU/mL). The proposed MRET strategy effectively improved the sensitivity and accuracy of the MRS immunosensor, offering a promising and versatile platform for food safety detection.

3D monitoring of the microphase separations inside the intraocular lens.

Glistenings often occur after implanting the intraocular lens (IOL) due to the formation of numerous microvacuoles (MVs) and may lead to deterioration of vision quality. Previous studies showed the formation of MVs was associated with the hydrophobicity of IOL materials. Yet, the mechanism remains an open question due to the complexity of IOL polymer networks. In this study, two commercialized IOLs with similar hydrophobicity are found distinct in the formation of MVs. The 3D growth kinetics of MVs during cooling processes are captured for the first time by digital holographic microscopy (DHM) and the components of MVs are measured by DHM and Raman spectroscopy. The results reveal that the growth of MVs stems from the microphase separation of water and surrounding IOL polymers. A polymer swelling model is thus proposed to describe the microphase separation process which is found dependent on the elasticity of IOL polymer networks. The total volume of MVs is determined by the IOL hydrophobicity, while the elastic force of IOL polymer networks determines the number density and size of MVs. This study demonstrates an approach for characterizing the phase separation of crosslinked polymeric materials in biosystems and sheds lights on the refinement of IOL materials. STATEMENT OF SIGNIFICANCE: Glistenings due to the formation of numerous microvacuoles (MVs) in intraocular lens (IOL) can occur after IOL implantation, which may induce poor quality of vision. However, the underlying mechanism of MVs formation is still an open question. This study establishes an in-situ 3D imaging platform to monitor growth kinetics of the MVs in IOLs, which allows to uncover the mechanism of glistenings formation resulting from the microphase separation. The findings imply the material hydrophobicity influences the total volume of MVs, while the local elasticity of IOL polymer networks determines the number density and the size of MVs. This study offers a new approach for characterizing phase separation in crosslinking biosystems and sheds lights on the refinement of IOL materials.

T cell immunoglobulin and immunoreceptor tyrosine-based inhibitory motif domain as a promising immune checkpoint target for the treatment of SLE.

Immune checkpoints (ICs) play a pivotal role in orchestrating immune regulation, crucial for the maintenance of immune tolerance and prevention of autoimmune diseases. One noteworthy example among these immune regulators is T cell immunoglobulin (Ig) and immunoreceptor tyrosine-based inhibitory motif (ITIM) domain (TIGIT). The TIGIT pathway's inhibition or the absence of TIGIT has been linked to the hyperactivation and excessive proliferation of T cells, rendering individuals more susceptible to autoimmune diseases and exacerbating inflammatory responses. Conversely, the activation of TIGIT has exhibited promising outcomes in ameliorating autoimmune disorders, as observed in murine models of systemic lupus erythematosus (SLE). Consequently, a judicious exploration of the co-inhibitory axis appears warranted for the effective management of pathogenic immune responses in SLE. In light of compelling evidence, this review undertakes a comprehensive examination of TIGIT's characteristics within the context of autoimmunity, offering insights into its potential as a therapeutic target for SLE.

Virus-Inspired Glucose and Polydopamine (GPDA)-Coating as an Effective Strategy for the Construction of Brain Delivery Platforms.

The ability of drugs to cross the blood-brain barrier (BBB) is crucial for treating central nervous system (CNS) disorders. Inspired by natural viruses, here we report a glucose and polydopamine (GPDA) coating method for the construction of delivery platforms for efficient BBB crossing. Such platforms are composed of nanoparticles (NPs) as the inner core and surface functionalized with glucose-poly(ethylene glycol) (Glu-PEG) and polydopamine (PDA) coating. Glu-PEG provides selective targeting of the NPs to brain capillary endothelial cells (BCECs), while PDA enhances the transcytosis of the NPs. This strategy is applicable to gold NPs (AuNPs), silica, and polymeric NPs, which achieves as high as 1.87% of the injected dose/g of brain in healthy brain tissues. In addition, the GPDA coating manages to deliver NPs into the tumor tissue in the orthotopic glioblastoma model. Our study may provide a universal strategy for the construction of delivery platforms for efficient BBB crossing and brain drug delivery.

Marriage of Organic and Grubbs Catalysts for Tandem Synthesis of Bottlebrush Polyesters.

Bottlebrush polymers (BBPs) have gained wide attention for their special characters, such as rigid main/side chains, stemming from the exceedingly high graft density. This study aims to provide a simple synthetic approach to BBPs with polyester side chains by merging ring-opening alternating copolymerization (ROAP) and ring-opening metathesis polymerization (ROMP). A simple phosphazene base (tBuP1) is employed for the ROAP of phthalic anhydride and epoxide, after which Grubbs third-generation catalyst (G3) is added to in situ switch on ROMP of the macromonomer, i.e., norbornenyl-ended alternating polyester. The compatibility of tBuP1 with G3 and well-controlled ROMP is evidenced by DOSY-NMR of mixed catalysts, characterization of BBPs, and side-chain degradation. The method can also be extended to BBPs with one-step synthesized block copolyesters side chains. These results highlight the strength of the non-nucleophilic organobase catalyst for convenient construction of complex (degradable) polymers with compositional diversity.

Reservoir computing-based digital signal equalizer for equivalent-time sampling.

A sampling oscilloscope is an important instrument for evaluating the quality of optical communication signals. Since its working principle is equivalent-time sampling, the data obtained for digital signals with random characteristics do not have continuity, which makes it impossible to use methods such as filtering and averaging to equalize the signal. For this reason, this paper proposes a signal equalization method based on reservoir computing. Through training of the reservoir model, an equivalent-time equalizer is established to solve the problem that the sampling oscilloscope cannot equalize random digital signals. Compared with the continuous-time equalizer, the coincidence degree exceeds 95%. The eye height and eye width are increased by 7 and 1.6, respectively, while the jitter in the eye diagram is reduced by 2.3 times, which solves the problem that the sampling oscilloscope cannot equalize random digital signals.

DNA Extraction- and Amplification-Free Nucleic Acid Biosensor for the Detection of Foodborne Pathogens Based on CRISPR/Cas12a and Argonaute Protein-Mediated Cascade Signal Amplification.

A novel method for detecting low levels of viable foodborne pathogens, specifically Salmonella typhimurium (S. typhimurium), has been developed. Traditional nucleic acid assay, such as polymerase chain reaction (PCR), often requires complex DNA extraction and amplification, making it challenging to differentiate between viable and nonviable pathogens. This assay employed a phage as the recognition element to precisely identify and lyse viable S. typhimurium that can undergo DNA extraction. It combined the efficient trans-cleavage activities of CRISPR/Cas12a with the specific cleavage advantages of Argonaute proteins, enabling ultrasensitive detection. This double-enzyme-mediated nucleic acid test can accurately distinguish viable and nonviable S. typhimurium with a detection limit of 23 CFU/mL without DNA amplification. The method was successfully applied to common food samples, producing results consistent with quantitative PCR tests. This work provides a promising platform for easily detecting viable foodborne pathogens with high sensitivity without the need for DNA extraction and amplification.

Chemoselectivity Streamlines the Approach to Linear and Y-Shaped Thiol-Polyethers Starting from Thiocarboxylic Acids.

Thiol-functionalized polyethers, especially poly(ethylene oxide) (PEO), have extensive applications in biomedicine and materials sciences. Herein, we report a simple one-pot synthesis of α-thiol-ω-hydroxyl polyethers through ring-opening polymerization (ROP) of epoxides using thiocarboxylic acid initiators followed by in situ aminolysis. The efficient and chemoselective metal-free Lewis pair catalyst avoids transthioesterification thus achieving well-controlled molar mass, low dispersity, and high end-group fidelity. Kinetic and calculation results demonstrated a fast-initiation mode of the ROP for the strong nucleophilicity of the thiocarboxylate anion and its weak interaction with Lewis acid. The method is expanded for α-thiol-ω-dihydroxyl (Y-shaped) PEO by virtue of the stability of thioester during the ROP. The thiol functionality in linear/Y-shaped PEO is further corroborated by the intensified interaction with gold surface and the resultant protein resistance behavior.

Computer Vision-Based Artificial Intelligence-Mediated Encoding-Decoding for Multiplexed Microfluidic Digital Immunoassay.

Digital immunoassays with multiplexed capacity, ultrahigh sensitivity, and broad affordability are urgently required in clinical diagnosis, food safety, and environmental monitoring. In this work, a multidimensional digital immunoassay has been developed through microparticle-based encoding and artificial intelligence-based decoding, enabling multiplexed detection with high sensitivity and convenient operation. The information encoded in the features of microspheres, including their size, number, and color, allows for the simultaneous identification and accurate quantification of multiple targets. Computer vision-based artificial intelligence can analyze the microscopy images for information decoding and output identification results visually. Moreover, the optical microscopy imaging can be well integrated with the microfluidic platform, allowing for encoding-decoding through the computer vision-based artificial intelligence. This microfluidic digital immunoassay can simultaneously analyze multiple inflammatory markers and antibiotics within 30 min with high sensitivity and a broad detection range from pg/mL to µg/mL, which holds great promise as an intelligent bioassay for next-generation multiplexed biosensing.

TIGIT-Fc fusion protein alleviates murine lupus nephritis through the regulation of SPI-B-PAX5-XBP1 axis-mediated B-cell differentiation.

OBJECTIVES: T cell immunoglobulin and immunoreceptor tyrosine-based inhibitory motif (ITIM) domain (TIGIT) is a newly discovered immune checkpoint (IC) that exhibits immunosuppressive function in the regulation of immune system. Activation of TIGIT signaling has emerged as a promising approach for autoimmune disease immunotherapy, such as systemic lupus erythematosus (SLE). METHODS: We generated a chimeric protein, TIGIT-immunoglobulin (Ig), by fusing the extracellular domain of murine TIGIT to the Fc region of mouse IgG2a, which was used to investigated the effect of activating the TIGIT signaling in murine lupus models (MRL/lpr and chronic graft-versus-host disease mice). Treated mice were harvested, and samples of serum, kidney, and spleen were collected for outcome evaluation. In vitro treatment of TIGIT-Ig in B cells was used for exploring the roles of TIGIT in toll-like receptor 7 (TLR7)-mediated B cell differentiation and antibody production. RESULTS: TIGIT-Ig treatment delayed disease progression in both lupus models, accompanied by a decrease in the production of anti-double stranded DNA antibodies (anti-dsDNA), proteinuria, proteinuria/creatinine, and Ig kidney deposition. Additionally, the group treated with TIGIT-Ig displayed a decreased proportion of T helper cell (Th)1 cells, T follicular helper (Tfh) cells, and B-cell subsets, including germinal center B cells (GC B), plasmablasts, and plasma cells, compared to the group treated with control IgG. Interestingly, we also observed an increased proportion of Tregs in the spleen of the TIGIT-Ig group. We have discovered a new way in which activating the TIGIT pathway can regulate B-cell differentiation through the SPI-B-PAX5-XBP1 pathway, resulting in a reduction in autoantibodies. CONCLUSION: Together, TIGIT may be a promising IC target for SLE treatment.

TIGIT: An emerging immune checkpoint target for immunotherapy in autoimmune disease and cancer.

Immune checkpoints (ICs), also referred to as co-inhibitory receptors (IRs), are essential for regulating immune cell function to maintain tolerance and prevent autoimmunity. IRs, such as programmed cell death protein 1 (PD-1) and cytotoxic T-lymphocyte-associated protein 4 (CTLA-4), have been shown to possess immunoregulatory properties that are relevant to various autoimmune diseases and cancers. Tumors are characterized by suppressive microenvironments with elevated levels of IRs on tumor-infiltrating lymphocytes (TILs). Therefore, IR blockade has shown great potential in cancer therapy and has even been approved for clinical use. However, other IRs, including cell immunoglobulin and immunoreceptor tyrosine-based inhibitory motif (ITIM) domain (TIGIT), may also represent promising targets for anti-tumor therapy. The increasing importance of IRs in autoimmune diseases has become apparent. In mouse models, TIGIT pathway blockade or TIGIT deficiency has been linked to T cell overactivation and proliferation, exacerbation of inflammation, and increased susceptibility to autoimmune disorders. On the other hand, TIGIT activation has been shown to alleviate autoimmune disorders in murine models. Given these findings, we examine the effects of TIGIT and its potential as a therapeutic target for both autoimmune diseases and cancers. It is clear that TIGIT represents an emerging and exciting target for immunotherapy in these contexts.

Nanoblock-mediated selective oncolytic polypeptide therapy for triple-negative breast cancer.

Rationale: Broad-spectrum oncolytic peptides (Olps) constitute potential therapeutic options for treating heterogeneous triple-negative breast cancer (TNBC); however, their clinical application is limited owing to high toxicity. Methods: A nanoblock-mediated strategy was developed to induce selective anticancer activity of synthetic Olps. A synthetic Olp, C12-PButLG-CA, was conjugated to the hydrophobic or hydrophilic terminal of a poly(ethylene oxide)-b-poly(propylene oxide) nanoparticle or a hydrophilic poly(ethylene oxide) polymer. A nanoblocker, that can significantly reduce the toxicity of Olp, was screened out through hemolytic assay, and then Olps were conjugated to the nanoblock via a tumor acidity-cleavable bond to obtain the selective RNolp ((mPEO-PPO-CDM)2-Olp). The tumor acidity responsive membranolytic activity, in vivo toxicity and anti-tumor efficacy of RNolp were determined. Results: We found that the conjugation of Olps to the hydrophobic core of a nanoparticle but not the hydrophilic terminal or a hydrophilic polymer restricts their motion and drastically reduces their hemolytic activity. We then covalently conjugated Olps to such a nanoblock via a cleavable bond that can be hydrolyzed in the acidic tumor environment, yielding a selective RNolp molecule. At physiological pH (pH 7.4), RNolp remained stable with the Olps shielded by nanoblocks and exhibited low membranolytic activity. At the acidic tumor environment (pH 6.8), Olps could be released from the nanoparticles via the hydrolysis of the tumor acidity-cleavable bonds and exerted membranolytic activity against TNBC cells. RNolp is well tolerated in mice and demonstrated high antitumor efficacy in orthotopic and metastatic mouse models of TNBC. Conclusion: We developed a simple nanoblock-mediated strategy to induce a selective cancer therapy of Olps for TNBC.

Janus Effect of Lewis Acid Enables One-Step Block Copolymerization of Ethylene Oxide and N-Sulfonyl Aziridine.

One-step sequence-selective block copolymerization requires stringent catalytic control of monomers relative activity and enchainment order. It has been especially rare for An Bm -type block copolymers from simple binary monomer mixtures. Here, ethylene oxide (EO) and N-sulfonyl aziridine (Az) compose a valid pair provided with a bicomponent metal-free catalyst. Optimal Lewis acid/base ratio allows the two monomers to strictly block-copolymerize in a reverse order (EO-first) as compared with the conventional anionic route (Az-first). Livingness of the copolymerization facilitates one-pot synthesis of multiblock copolymers by addition of mixed monomers in batches. Calculation results reveal that a Janus effect of Lewis acid on the two monomers is key to enlarge the activity difference and reverse the enchainment order.

Discovery of N-l-Lactoyl-l-Trp as a Bitterness Masker via Structure-Based Virtual Screening and a Sensory Approach.

N-Lactoyl-amino acid derivatives (N-Lac-AAs) are of increasing interest as potential taste-active compounds. The complexity and diversity of N-Lac-AAs pose a significant challenge to the effective discovery of taste-active N-Lac-AAs. Therefore, a structure-based virtual screening was used to identify taste-active N-Lac-AAs. Virtual screening results showed that N-lactoyl-hydrophobic amino acids had a higher affinity for taste receptors, specifically N-l-Lac-l-Trp. And then, N-l-Lac-l-Trp was synthesized in yields of 22.3% by enzymatic synthesis in the presence of l-lactate and l-Trp, and its chemical structure was confirmed by MS/MS and one-dimensional (1D) and two-dimensional (2D) NMR. Sensory evaluation revealed that N-l-Lac-l-Trp had a significant taste-masking effect on quinine, d-salicin, caffeine, and l-Trp, particularly l-Trp and caffeine. N-l-Lac-l-Trp had a better masking effect on the higher concentration of bitter compounds. It reduced the bitterness of caffeine (500 mg/L) and l-Trp (1000 mg/L) by approximately 20 and 26%, respectively. The result of the ligand-receptor interaction and a quantum mechanical analysis showed that N-l-Lac-l-Trp increased the binding affinity to the bitter receptor mainly through hydrogen bonding and lowering the electrostatic potential.

Tuning the Properties of Ester-Based Degradable Polymers by Inserting Epoxides into Poly(ϵ-caprolactone).

A series of ester-ether copolymers were obtained via the reaction between α,ω-dihydroxyl poly(ϵ-caprolactone) (PCL) and ethylene oxide (EO) or monosubstituted epoxides catalyzed by strong phosphazene bases. The two types of monomeric units were distributed in highly random manners due to the concurrence of epoxide ring-opening and fast transesterification reactions. The substituent of epoxide showed an interesting bidirectional effect on the enzymatic degradability of the copolymer. Compared with PCL, copolymers derived from EO exhibited enhanced hydrophilicity and decreased crystallinity which then resulted in higher degradability. For the copolymers derived from propylene oxide and 1,2-butylene oxide, the hydrophobic alkyl pendant groups also allowed lower crystallinity of the copolymers thus higher degradation rates. However, further enlarging the pendant groups by using styrene oxide or 2-ethylhexyl glycidyl ether caused a decrease in the degradation rate, which might be ascribed to the higher bulkiness hindering the contact of ester groups with lipase.

A phage-based magnetic relaxation switching biosensor using bioorthogonal reaction signal amplification for Salmonella detection in foods.

Phages are uniquely suited for bacterial detection due to their low cost and ability to recognize live bacteria. Herein, our work establishes the proof-of-concept detection of Salmonella in orange juice based on a phage-mediated portable magnetic relaxation switching (MRS) biosensor. The limit of quantification (LOQ) could reach 5 CFU/mL (95 % confidence interval [CI]: 4-7, N = 4) with a linear range of 102-108 CFU/mL, which has improved 10-fold than that without bioorthogonal signal amplification. The recovery rate of the phage-based MRS biosensor was 95.0 % (95 % confidence interval [CI]: 89.0 %-100.9 %, N = 6). The specificity of the phage-based MRS biosensor was 100 % without false-positive results. In addition, this sensor was able to detect <10 CFU per 25 mL of Salmonella in orange juice with 4-h pre-enrichment. The result from the phage-based MRS biosensor is consistent with that from the standard plate count method. This sensor provides a reliable and ultrasensitive detection platform for pathogens.

Polydopamine-mediated quantity-based magnetic relaxation sensing for the rapid and sensitive detection of chloramphenicol in fish samples.

Chloramphenicol is an antibiotic that cause adverse effects in humans. In this work, a novel quantity-based magnetic relaxation switching (sMRS) sensor using polydopamine (PDA) for signal amplification was successfully developed for the rapid and sensitive detection of chloramphenicol in fish samples. We first prepared the conjugation of large magnetic nanoparticles (MNPs) and CAP antigen (MNP-antigen), which performed a competitive immune reaction with chloramphenicol and chloramphenicol antibody. Horseradish peroxidase, that can bind to antibody at the surface of large MNPs, was employed to catalyze the rapid polymerization of dopamine to PDA, which was easily deposited onto the surface of large MNPs. The concentration of chloramphenicol is inversely proportional to the content of HRP after reaction, in other words, it is inversely proportional to the content of PDA. PDA then reacted with 30 nm-diameter amine-functionalized MNPs (NH2-MNP30), the consumption of which resulted in a decrease in the concentration of free NH2-MNP30 particles in solution. After magnetic separation, the remaining free NH2-MNP30 served as the magnetic probe for signal readout. The limit of detection of the sMRS assay for detecting chloramphenicol was 16.6 pg/mL, which was 49-fold lower than MRS sensor without signal amplification. This quantity-based MRS sensor can provide a powerful platform for enabling the rapid and sensitive detection of chloramphenicol in food samples.