An ultrasensitive and selective chemiluminescence (CL) assay system for the detection of platelet-derived growth factor (PDGF)-BB was developed by taking advantage of the powerful signal amplification capability of rolling circle amplification (RCA) and a hydroxylamine-amplified gold nanoparticle (Au NP)-based CL technique. Rabbit anti-human PDGF-BB polyclonal antibody was covalently coupled on the surface of a 96-well plate that offers the reactive N-oxysuccinimide (NOS) group. In the presence of PDGF-BB, the aptamer–primer oligonucleotides were bound to the surface-captured antigen, resulting in an analyte-specific single-stranded DNA that could serve as the prime for the RCA reaction. The captured aptamer–primer was extended through the RCA reaction forming a single-stranded tandem repeated biotinylated copy of the circular template. After binding of the RCA product with streptavidin-gold (SA-Au NPs), the assembled Au NPs were enlarged by a NH2OH–HAuCl4 redox reaction allowing gold metal to be catalytically deposited onto the surface of the Au NPs. After an oxidative gold metal dissolution, a huge number of Au3+ ions were released from the enlarged Au NPs and were determined by a simple and sensitive luminol CL reaction. With two successive amplification steps, the proposed CL assay system exhibits not only high sensitivity with the detection limit of PDGF-BB as low as 0.06 pM (corresponding to 3 amol in 50 μL of sample solution), but also high specificity by taking advantage of using aptamers as recognition elements. In addition, PDGF-BB has been determined in diluted serum indicating the applicability of this assay.

A highly sensitive and selective chemiluminescent (CL) biosensor for adenosine triphosphate (ATP) was developed by taking advantage of the ATP-dependent enzymatic reaction (ATP-DER), the powerful signal amplification capability of rolling circle amplification (RCA), and hydroxylamine-amplified gold nanoparticles (Au NPs). The strategy relies on the ability of ATP, a cofactor of T4 DNA ligase, to trigger the ligation-RCA reaction. In the presence of ATP, the T4 DNA ligase catalyzes the ligation reaction between the two ends of the padlock probe, producing a closed circular DNA template that initiates the RCA reaction with phi29 DNA polymerase and dNTP. Therein, many complementary copies of the circular template can be generated. The ATP-DER is eventually converted into a detectable CL signal after a series of processes, including gold probe hybridization, hydroxylamine amplification, and oxidative gold metal dissolution coupled with a simple and sensitive luminol CL reaction. The CL signal is directly proportional to the ATP level. The results showed that the detection limit of the assay is 100 pM of ATP, which compares favorably with those of other ATP detection techniques. In addition, by taking advantage of ATP-DER, the proposed CL sensing system exhibits extraordinary specificity towards ATP and could distinguish the target molecule ATP from its analogues. The proposed method provides a new and versatile platform for the design of novel DNA ligation reaction-based CL sensing systems for other cofactors. This novel ATP-DER based CL sensing system may find wide applications in clinical diagnosis as well as in environmental and biomedical fields.

Graphene oxide (GO) was for the first time designed as a bionanolabel for sensitive chemiluminescent (CL) immunosensing of human IgG by taking advantage of a magnetic separation–mixing process and a GO-triggered luminol–H2O2 CL reaction. The detection limit of the concentration of human IgG is 1.2 pg mL−1, which is comparable with or better than other immunoassays.

An ultrasensitive and selective chemiluminescence (CL) assay system for the detection of platelet-derived growth factor (PDGF)-BB was developed by taking advantage of the powerful signal amplification capability of rolling circle amplification (RCA) and a hydroxylamine-amplified gold nanoparticle (Au NP)-based CL technique. Rabbit anti-human PDGF-BB polyclonal antibody was covalently coupled on the surface of a 96-well plate that offers the reactive N-oxysuccinimide (NOS) group. In the presence of PDGF-BB, the aptamer–primer oligonucleotides were bound to the surface-captured antigen, resulting in an analyte-specific single-stranded DNA that could serve as the prime for the RCA reaction. The captured aptamer–primer was extended through the RCA reaction forming a single-stranded tandem repeated biotinylated copy of the circular template. After binding of the RCA product with streptavidin-gold (SA-Au NPs), the assembled Au NPs were enlarged by a NH2OH–HAuCl4 redox reaction allowing gold metal to be catalytically deposited onto the surface of the Au NPs. After an oxidative gold metal dissolution, a huge number of Au3+ ions were released from the enlarged Au NPs and were determined by a simple and sensitive luminol CL reaction. With two successive amplification steps, the proposed CL assay system exhibits not only high sensitivity with the detection limit of PDGF-BB as low as 0.06 pM (corresponding to 3 amol in 50 μL of sample solution), but also high specificity by taking advantage of using aptamers as recognition elements. In addition, PDGF-BB has been determined in diluted serum indicating the applicability of this assay.

Graphene oxide (GO) was for the first time designed as a bionanolabel for sensitive chemiluminescent (CL) immunosensing of human IgG by taking advantage of a magnetic separation–mixing process and a GO-triggered luminol–H2O2 CL reaction. The detection limit of the concentration of human IgG is 1.2 pg mL−1, which is comparable with or better than other immunoassays.