Polystyrene Microspheres Coupled with Hybridization Chain Reaction for Dual‑Amplified Chemiluminescence Detection of Specific DNA Sequences

We report on a highly sensitive chemiluminescence(CL)assay for the detection of specific DNA sequence,where streptavidin-modified polystyrene microspheres(PS–SA)coupled with hybridization chain reaction(HCR)were employed as dual amplification platform.Briefly,a“sandwich-type”detection strategy was proposed in our design,which involved capture probe DNA immobilized on the surface of carboxyl-terminated magnetic beads(MB)and the reporter DNA combined with the HCR trigger immobilized on the surface of PS–SA.After that,two hairpin-type monomers were added to initiate the HCR.In the detection system,CL signal was obtained via the instantaneous derivatization reaction between 3,4,5-trimethoxylphenylglyoxal(TMPG)and guanine bases in the target and the HCR complex binding on the magnetic beads.As compared to traditional sandwich type(capture/target/reporter)assays,this dual-amplified strategy for sequence-specific DNA detection showed better specificity,lower detection limit and wider linear response range(linear range of 0.01 fmol–10 pmol and a low detection limit of 5 amol).Moreover,this approach could be easily extended to detect a wide range of specific DNA sequences by modification of the hybridization region.We believe this simple technique will present a significant step towards early diagnoses of diseases.

Preparation and Catalytic Performance of Microporous Polymer/Au Nanoparticles Composite Microspheres

Polystyrene crosslinked microspheres were prepared by soap-free emulsion polymerization using styrene (St) and divinylbenzene (DVB) as monomers;then,the microporous structure was knitted by the Friedel-Crafts alkylation reaction,and the Au nanoparticles (AuNPs) were loaded into the pores through thermal reduction,to obtain AuNPs/ hyper-crosslinked microporous polymer composite microspheres.SEM and particle-size test results show that the microspheres show good monodispersity.The micropore analysis indicates that the specific surface area and the pore volume of the microporous polymer microspheres decrease with increasing DVB content,and when the DVB content is 0.1%,the specific surface area reaches a maximum of 1 174.6 m2/g.After loading AuNPs,the specific surface area and the amount of micropores of the composite microspheres decrease obviously.The results of XRD and XPS analyses suggest that HAuCl4 is reduced to AuNPs.The composite microspheres show a good catalytic performance for the reduction catalyst of 4-nitrophenol.

Comparison of Two Rhodamine-Polyamine Polystyrene Solid-phase Fluorescence Sensors for Hg(Ⅱ) Detection Based on Theoretical Calculation

Two novel rhodamine-based polystyrene solid-phase fluorescence sensors PS-PA-Ⅰ and PS・PA-Ⅱ with different lengths of polyamines were synthesized for Hg(Ⅱ)determination.Thedetection mechanism involving the Hg(Ⅱ)chelation-induced spirocycle open of rhodamine was proposed with the aid of theoretical calculation.The stronger N—Hg bond and the longer polyamine chain in PS-PA-Ⅱ led to a better selectivity,much higher and more quickly fluorescence response to Hg(Ⅱ).

One-step polymerized lanthanide-based polystyrene microsphere for sensitive lateral flow immunoassay

Lateral flow immunoassays(LFIAs)provide a powerful tool for rapid real-time assay of cancer biomarkers,which is vital for cancer detection and treatment follow-up.Lanthanide-based LFIAs is one of the most widely used methods,especially Eu(Ⅲ)chelates,which possess distinctive and attractive characteristics,such as time-resolved fluorescence and large Stokes shift.Herein,we adopted a new onestep mini-emulsion polymerization method to synthesize carboxyl-modified fluorescent microsphere(OS-EuCM),which shows good stability,resistance to non-specific adhesion and uniform particle size distribution compared with traditional microspheres synthesized through the swelling method.Benefiting from the above advantages,OS-EuCM was successfully used in LFIAs to detect tumor marker Alpha-fetoprotein with high sensitivity and selectivity in concentration as high as 320 ng/mL,as well as a detection limit of 0.683 ng/mL This lanthanide-based microsphere holds great potential for rapid pointof-care screening and clinical application.

A Miniature Fiber Tip Polystyrene Microsphere Temperature Sensor With High Sensitivity

A fiber-optic temperature sensor based on fiber tip polystyrene microsphere is proposed.The sensor structure can be formed simply by placing and fixing a polystyrene microsphere on the center of an optical fiber tip.Since polystyrene has a much larger thermal expansivity,the structure can be used for high-sensitive temperature measurement.By the illuminating of the sensor with a broadband light source and through the optical Fabry-Perot interference between the front and back surfaces of the polystyrene microsphere,the optical phase difference(OPD)or wavelength shift can be used for the extraction of temperature.Temperature measurement experiment shows that,using a fiber probe polystyrene microsphere temperature sensor with a spherical diameter of about 91.7 pm,a high OPD-temperature sensitivity of about-0.61796nm/℃and a good linearity of 0.9916 were achieved in a temperature range of 20℃-70℃.