Objective This study aimed to investigate the antimicrobial resistance profiles of bacterial strains isolated from pediatric intensive care units(PICU)in China for better antimicrobial therapy.Methods Clinical isolates were collected from 17 institutions,including tertiary care children's hospitals and pediatric department of tertiary general hospitals in China from January 1,2020 to December 31,2022.Antimicrobial susceptibility testing was carried out according to a unified protocol using Kirby-Bauer method or automated systems.Results were interpreted according to the breakpoints released by the Clinical and Laboratory Standards Institute(CLSI)in 2020.Results A total of 10 688 isolates were collected,including gram-positive organisms(39.2％)and gram-negative organisms(60.8％).The top three organisms were S.aureus(13.6％,1 453/10 688),A.baumannii(10.0％,1 067/10 688),and coagulase-negative Staphylococcus(9.9％,1 058/10 688).Multi-drug resistant organisms(MDROs)were very common in children.The prevalence of methicillin-resistant Staphylococcus aureus(MRSA),carbapenem-resistant Enterobacterales(CRE),carbapenem-resistant E.coli,carbapenem-resistant K.pneumoniae(CRKP),carbapenem-resistant A.baumannii(CRAB),and carbapenem-resistant P.aeruginosa(CRPA)was 41.1％,19.4％,8.8％,30.9％,67.4％,and 28.8％,respectively.Overall,more than 50％of Enterobacteriales isolates were resistant to cephalosporins,while nearly 25％of Enterobacteriales isolates were resistant to carbapenems.MDROs were highly resistant to commonly used antibiotics.More than 80％of CRE and CRAB strains were resistant to all beta-lactam antibiotics.CRE and CRAB showed low resistance rates to tigecycline and polymyxin.CRPA showed lower resistance rates to piperacillin,beta-lactamase inhibitor combinations than the resistance rates to third and fourth generation cephalosporins.All of the Staphylococcus and Enterococcus isolates were susceptible to vancomycin and tigecycline.None of PRSP strains isolated from meningitis and nonmeningitis samples were resistant to rifampicin,vancomycin,or linezolid.The prevalence of β-lactamase-negative ampicillin-resistant(BLNAR)strains was 43.3％in Haemophilus influenzae.Conclusions MDROs were prevalent in PICU.It is necessary to establish an effective multidisciplinary team(MDT)to control the antimicrobial resistance.

AIM:To investigate the effect of drug-containing serum of oxytropis falcata extract on oxi-dative stress injury of podocyte induced by high glucose through PI3K/AKT/Nrf2 pathway.METH-ODS:The rat renal podocyte was cultured in vitro,and the concentration and time of D-glucose mod-elling and the optimal concentration and time of administration in the drug-containing serum of oxy-tropis falcata extract were screened.The cells were divided into normal group,high glucose group,high glucose+blank serum group,oxytropis falcata group,inhibitor group,oxytropis falcata+inhibitor group.Rhodamine staining and electron microsco-py were used to observe the morphological and pathological changes of podocyte,flow cytometry was used to detect apoptosis rate,and cell migra-tion ability was detected by scratch test.Immuno-fluorescence and fluorescence probe were used to detect the fluorescence expression of p-AKT and ROS level of cells,ELISA was used to detect the con-tent of MDA,NO,SOD and T-AOC in the superna-tant of cells,and Western Blot was used to detect the protein expression of p-PI3K/PI3K,p-AKT/AKT and Nrf2 in cells.The mRNA expressions of Nrf2,HO-1,GCLM and SOD were detected by RT-qPCR.RESULTS:It was selected that 45 mmol/LD-glucose induction for 48 hours was the best modeling con-dition,and the 1-fold dilution of the medicated se-rum of oxytropis falcata extract for 48 hours was the best concentration and intervention time.Com-pared with the normal group,the foot processes of the high glucose group were widely fused and ad-hered to each other,the apoptosis rate,migration ability and intracellular ROS level were significantly increased(P＜0.01),the fluorescence expression of p-AKT was markedly decreased(P＜0.01),the con-tents of MDA and NO were dramatically enhanced,and the contents of SOD and T-AOC were signifi-cantly downregulated(P＜0.01).The protein expres-sion of p-PI3K/PI3K,p-AKT/AKT,Nrf2 and the mRNA expression of Nrf2,HO-1,GCLM and SOD markedly declined(P＜0.01).Compared with high glucose group,foot process fusion and adhesion of podo-cytes in oxytropis falcata group and oxytropis falca-ta+inhibitor group were improved in varying de-grees,apoptosis rate,migration ability and intracel-lular ROS level significantly declined(P＜0.05,P＜0.01),p-AKT fluorescence expression increased(P＜0.01),NO content decreased,T-AOC level elevated(P＜0.01);the content of MDA decreased and the activity of SOD notably rose(P＜0.01),the protein expression of p-PI3K/PI3K,p-AKT/AKT,Nrf2 and the mRNA expression of Nrf2,HO-1,GCLM and SOD markedly increased in oxytropis falcata group(P＜0.05,P＜0.01);the level of ROS in podocytes im-proved(P＜0.01),the fluorescence expression of p-AKT decreased(P＜0.05),the content of NO upregu-lated,the content of T-AOC downregulated,and the expression of p-PI3K/PI3K,p-AKT/AKT,Nrf2 pro-tein and HO-1,GCLM,SOD mRNA decreased in in-hibitor group(P＜0.05,P＜0.01).Compared with oxy-tropis falcata group,the apoptosis rate,migration ability and intracellular ROS level of podocytes in oxytropis falcata+inhibitor group markedly in-creased(P＜0.05,P＜0.01),p-AKT fluorescence ex-pression declined(P＜0.01),MDA and NO content increased,SOD and T-AOC content decreased(P＜0.05,P＜0.01),p-PI3K/PI3K,p-AKT/AKT,Nrf2 protein and Nrf2,HO-1,GCLM,SOD mRNA expression all dramatically downregulated(P＜0.05,P＜0.01).CON-CLUSION:Oxytropis falcata extract may protect podocytes by activating the PI3K/AKT/Nrf2 signal-ing pathway,thereby improving the morphological,structural and functional changes of podocytes in-duced by high glucose and inhibiting oxidative stress response.

AIM:To investigate the effect of drug-containing serum of oxytropis falcata extract on oxi-dative stress injury of podocyte induced by high glucose through PI3K/AKT/Nrf2 pathway.METH-ODS:The rat renal podocyte was cultured in vitro,and the concentration and time of D-glucose mod-elling and the optimal concentration and time of administration in the drug-containing serum of oxy-tropis falcata extract were screened.The cells were divided into normal group,high glucose group,high glucose+blank serum group,oxytropis falcata group,inhibitor group,oxytropis falcata+inhibitor group.Rhodamine staining and electron microsco-py were used to observe the morphological and pathological changes of podocyte,flow cytometry was used to detect apoptosis rate,and cell migra-tion ability was detected by scratch test.Immuno-fluorescence and fluorescence probe were used to detect the fluorescence expression of p-AKT and ROS level of cells,ELISA was used to detect the con-tent of MDA,NO,SOD and T-AOC in the superna-tant of cells,and Western Blot was used to detect the protein expression of p-PI3K/PI3K,p-AKT/AKT and Nrf2 in cells.The mRNA expressions of Nrf2,HO-1,GCLM and SOD were detected by RT-qPCR.RESULTS:It was selected that 45 mmol/LD-glucose induction for 48 hours was the best modeling con-dition,and the 1-fold dilution of the medicated se-rum of oxytropis falcata extract for 48 hours was the best concentration and intervention time.Com-pared with the normal group,the foot processes of the high glucose group were widely fused and ad-hered to each other,the apoptosis rate,migration ability and intracellular ROS level were significantly increased(P＜0.01),the fluorescence expression of p-AKT was markedly decreased(P＜0.01),the con-tents of MDA and NO were dramatically enhanced,and the contents of SOD and T-AOC were signifi-cantly downregulated(P＜0.01).The protein expres-sion of p-PI3K/PI3K,p-AKT/AKT,Nrf2 and the mRNA expression of Nrf2,HO-1,GCLM and SOD markedly declined(P＜0.01).Compared with high glucose group,foot process fusion and adhesion of podo-cytes in oxytropis falcata group and oxytropis falca-ta+inhibitor group were improved in varying de-grees,apoptosis rate,migration ability and intracel-lular ROS level significantly declined(P＜0.05,P＜0.01),p-AKT fluorescence expression increased(P＜0.01),NO content decreased,T-AOC level elevated(P＜0.01);the content of MDA decreased and the activity of SOD notably rose(P＜0.01),the protein expression of p-PI3K/PI3K,p-AKT/AKT,Nrf2 and the mRNA expression of Nrf2,HO-1,GCLM and SOD markedly increased in oxytropis falcata group(P＜0.05,P＜0.01);the level of ROS in podocytes im-proved(P＜0.01),the fluorescence expression of p-AKT decreased(P＜0.05),the content of NO upregu-lated,the content of T-AOC downregulated,and the expression of p-PI3K/PI3K,p-AKT/AKT,Nrf2 pro-tein and HO-1,GCLM,SOD mRNA decreased in in-hibitor group(P＜0.05,P＜0.01).Compared with oxy-tropis falcata group,the apoptosis rate,migration ability and intracellular ROS level of podocytes in oxytropis falcata+inhibitor group markedly in-creased(P＜0.05,P＜0.01),p-AKT fluorescence ex-pression declined(P＜0.01),MDA and NO content increased,SOD and T-AOC content decreased(P＜0.05,P＜0.01),p-PI3K/PI3K,p-AKT/AKT,Nrf2 protein and Nrf2,HO-1,GCLM,SOD mRNA expression all dramatically downregulated(P＜0.05,P＜0.01).CON-CLUSION:Oxytropis falcata extract may protect podocytes by activating the PI3K/AKT/Nrf2 signal-ing pathway,thereby improving the morphological,structural and functional changes of podocytes in-duced by high glucose and inhibiting oxidative stress response.

Objective This study aimed to investigate the antimicrobial resistance profiles of bacterial strains isolated from pediatric intensive care units(PICU)in China for better antimicrobial therapy.Methods Clinical isolates were collected from 17 institutions,including tertiary care children's hospitals and pediatric department of tertiary general hospitals in China from January 1,2020 to December 31,2022.Antimicrobial susceptibility testing was carried out according to a unified protocol using Kirby-Bauer method or automated systems.Results were interpreted according to the breakpoints released by the Clinical and Laboratory Standards Institute(CLSI)in 2020.Results A total of 10 688 isolates were collected,including gram-positive organisms(39.2％)and gram-negative organisms(60.8％).The top three organisms were S.aureus(13.6％,1 453/10 688),A.baumannii(10.0％,1 067/10 688),and coagulase-negative Staphylococcus(9.9％,1 058/10 688).Multi-drug resistant organisms(MDROs)were very common in children.The prevalence of methicillin-resistant Staphylococcus aureus(MRSA),carbapenem-resistant Enterobacterales(CRE),carbapenem-resistant E.coli,carbapenem-resistant K.pneumoniae(CRKP),carbapenem-resistant A.baumannii(CRAB),and carbapenem-resistant P.aeruginosa(CRPA)was 41.1％,19.4％,8.8％,30.9％,67.4％,and 28.8％,respectively.Overall,more than 50％of Enterobacteriales isolates were resistant to cephalosporins,while nearly 25％of Enterobacteriales isolates were resistant to carbapenems.MDROs were highly resistant to commonly used antibiotics.More than 80％of CRE and CRAB strains were resistant to all beta-lactam antibiotics.CRE and CRAB showed low resistance rates to tigecycline and polymyxin.CRPA showed lower resistance rates to piperacillin,beta-lactamase inhibitor combinations than the resistance rates to third and fourth generation cephalosporins.All of the Staphylococcus and Enterococcus isolates were susceptible to vancomycin and tigecycline.None of PRSP strains isolated from meningitis and nonmeningitis samples were resistant to rifampicin,vancomycin,or linezolid.The prevalence of β-lactamase-negative ampicillin-resistant(BLNAR)strains was 43.3％in Haemophilus influenzae.Conclusions MDROs were prevalent in PICU.It is necessary to establish an effective multidisciplinary team(MDT)to control the antimicrobial resistance.

Imipenem-cilastatin is a broad-spectrum carbapenem antibiotic drug that has been widely used in clinical practice ， but there is a lack of guidelines and expert consensus on the development of individualized regimens for special status populations [e.g. continuous renal replacement therapy （CRRT）patients，extracorporeal membrane oxygenation （ECMO）patients， critically ill burn patients ，neonates and children]. In this paper ，by searching population pharmacokinetics research of imipenem- cilastatin in special status populations ，it is recommended that imipenem-cilastatin is given 1 to 3 g/d for CRRT patients ；500 mg to 1 g，q6 h for burn patients ；750 mg to 1 g，q6 h for ECMO patients ；20 mg/kg or 25 mg/kg，q8 h for neonates ；and 25 mg/kg，q6 h for children.

Purpose: This study aims to comprehensively evaluate the clinical efficacy of chemotherapy or endocrine therapy maintenance in metastatic breast cancer (MBC) patients. Materials and Methods: The meta-analysis of randomized clinical trials (RCTs) and propensity score matching of multicenter cohort study evaluated MBC patients who underwent first-line chemotherapy or endocrine therapy maintenance. This study is registered with PROSPERO: CRD42017071858 and ClinicalTrials.gov: NCT04258163. Results: A total of 2,867 patients from 15 RCTs and 760 patients from multicenter cohort were included. The results from meta-analysis showed that chemotherapy maintenance improved progression-free survival (PFS) (hazard ratio [HR], 0.63; 95% confidence interval [CI], 0.54 to 0.73; p < 0.001; moderate-quality evidence) and overall survival (OS) (HR, 0.87; 95% CI 0.78 to 0.97; p=0.016; high-quality evidence) than observation. In the cohort study, for hormone receptor–positive MBC patients, chemotherapy maintenance improved PFS (HR, 0.67; 95% CI, 0.52 to 0.85; p < 0.001) and OS (HR, 0.55; 95% CI 0.42 to 0.73; p < 0.001) compared with observation, and endocrine therapy maintenance also improved PFS (HR, 0.65; 95% CI, 0.53 to 0.80; p < 0.001) and OS (HR, 0.55; 95% CI, 0.44 to 0.69; p < 0.001). There were no differences between chemotherapy and endocrine therapy maintenance in PFS and OS (all p > 0.05). Regardless of the continuum or switch maintenance therapy, showed prolonged survival in MBC patients who were response to first-line treatment. Conclusion This study provided evidences for survival benefits of chemotherapy and endocrine therapy maintenance in MBC patients, and there was no difference efficacy between chemotherapy and endocrine therapy maintenance for hormone receptor–positive patients.

Objective:To explore the effects of necroptosis specific inhibitor-1 (Nec-1) on brain injury in rats after cardiac arrest and its mechanism.Methods:A total of 24 Sprague-Dawley (SD) rats were divided into Sham group, model group and Nec-1 group ( n = 8 per group) according to random number table method. In the Sham group, only general surgical procedures were underdone without inducing cardiac arrest. In the model group, the rats were subjected to asphyxial cardiac arrest followed by cardiopulmonary resuscitation (CPR) at 6 minutes after cardiac arrest. In the Nec-1 group, Nec-1 of 1 mg/kg was administered after cardiac arrest, and CPR was performed at 6 minutes after cardiac arrest. At 72 hours after CPR, neurological deficit scores (NDS) were assessed, serum S100B levels were measured by enzyme linked immunosorbent assay (ELISA), receptor-interacting protein 3 (RIP3) expression in cerebral cortex and hippocampus was observed under immunofluorescence and positive rate was calculated, and the levels of RIP3 protein expression in brain were analyzed by Western blotting. Results:At 72 hours after CPR, the rats in the model group showed obvious necroptosis and injury in brain. Compared with the Sham group, the NDS scores in the model group were significantly decreased [57.0 (52.7, 60.0) vs. 80.0 (80.0, 80.0), P < 0.05], the serum S100B was significantly increased (ng/L: 44.9±4.5 vs. 18.6±1.5, P < 0.05), the percentages of RIP3 positive cells in cerebral cortex and hippocampus were significantly elevated [cerebral cortex: (31.7±4.8)% vs. (11.6±3.2)%, hippocampus: (28.4±0.8)% vs. (10.9±0.6)%, both P < 0.05], and the levels of RIP3 protein expression in brain were significantly increased [RIP3 protein (RIP3/GAPDH): 0.708 (0.642, 0.722) vs. 0.408 (0.253, 0.504), P < 0.05]. After Nec-1 intervention, necroptosis and injury in brain were obviously improved. Compared with the model group, the NDS scores at 72 hours after CPR in the Nec-1 group were significantly increased [70.5 (68.5, 71.7) vs. 57.0 (52.7, 60.0), P < 0.05), the serum S100B was significantly decreased (ng/L: 31.9±2.7 vs. 44.9±4.5, P < 0.05), the percentages of RIP3 positive cells in cerebral cortex and hippocampus were significantly lowered [cerebral cortex: (23.7±4.1)% vs. (31.7±4.8)%, hippocampus: (20.4±0.4)% vs. (28.4±0.8)%, both P < 0.05], and the levels of RIP3 protein expression in brain were significantly declined [RIP3 protein (RIP3/GAPDH): 0.437 (0.379, 0.507) vs. 0.708 (0.642, 0.722), P < 0.05]. Conclusion:Nec-1 attenuated necroptosis of brain cells by inhibiting the expression of RIP3 protein, so as to reduce brain injury after cardiac arrest in rats.

Objective:To investigate the underlying molecular mechanisms of brain injury in rats after cardiac arrest and cardiopulmonary resuscitation (CPR) by observing necroptosis of brain cells and changes of 90 cytokines in brain tissue.Methods:Sprague-Dawley (SD) rats were divided into Sham group ( n = 10) and cardiac arrest group ( n = 10) according to random number table method. The model of asphyxia cardiac arrest for 6 minutes followed by CPR model was established. Tracheal intubation in Sham rats were routinely performed without inducing cardiac arrest. Neurological deficit score (NDS) was evaluated, blood samples were collected and rats were sacrificed, then serum S100B level was measured by enzyme linked immunosorbent assay (ELISA) on the third day after CPR. Necroptotic cells in brain were detected by immunofluorescence staining. The levels of 90 cytokines expression in brain were measured by antibody array. The relative ratio of the two groups of protein expression ≥ 1.5 or ≤ 0.5 and P < 0.05 represented the differential expression protein. Results:There were 8 rats successfully resuscitated and 2 died in cardiac arrest group. There were 8 rats selected in Sham group to match the sample size. Compared with Sham group, the NDS score of cardiac arrest group was significantly lower [63.0 (62.5, 64.3) vs. 80.0 (80.0, 80.0), P < 0.01], and the level of serum S100B was significantly higher (ng/L: 47.96±10.16 vs. 16.56±5.60, P < 0.01). More necroptotic cells in cerebral cortex and hippocampus were found in cardiac arrest group [proportion of cells positive for TdT-mediated nick end labeling (TUNEL) and negative for caspase-3: (15.70±0.32)% vs. (8.00±0.28)% in cortex, (20.80±1.35)% vs. (9.00±4.00)% in hippocampus, both P < 0.05]. The levels of inflammatory cytokines [cytokine-induced neutrophil chemoattractant (CINC-2α/β, CINC-3), interferon-γ (IFN-γ)] and signal protein c-Src kinase (CSK) in brain significantly increased after cardiac arrest as compared to Sham group levels (ratio of cardiac arrest group to Sham group: CINC-2 α/β was 2.503±0.428, P = 0.024; CINC-3 was 2.369±0.142, P = 0.005; IFN-γwas 3.149±1.362, P = 0.044; CSK was 1.887±0.105, P = 0.001). However, the levels of neuroprotective cytokines ciliary neurotrophic factor (CNTF), glial cell-derived neurotrophic factor receptor (GFR α-1, GFR α-2), growth hormone (GH), growth hormone receptor (GHR), granulocyte-macrophage colony-stimulating factor (GM-CSF) and anti-inflammatory protein interleukin-10 (IL-10) significantly decreased after cardiac arrest (ratio of cardiac arrest group to Sham group: CNTF was 0.341±0.137, P = 0.036; GFRα-1 was 0.461±0.164, P = 0.044; GFRα-2 was 0.447±0.017, P = 0.033; GH was 0.450±0.136, P = 0.024; GHR was 0.508±0.128, P = 0.022; GM-CSF was 0.446±0.130, P = 0.035; IL-10 was 0.502±0.211, P = 0.017). Conclusions:Necroptosis is involved in brain injury after cardiac arrest. The molecular mechanisms of brain injury may be related to inflammatory response, neurogenesis disorder and impaired survival of nerve cells.

Objective To prepare dual?modality single?photon emission computed tomography (SPECT)?MRI molecular nanoprobes targeting HAb18G/CD147 expressed on breast cancer cell membranes and investigate the physicochemical and biological properties in vitro. Methods Superparamagnetic iron oxide nanoparticles (SPIOs) were prepared by one?pot reaction method as described. The single?chain antibody fragments HAb18F(ab')2 were conjugated to SPIOs via chemical method and then labeled with 125I using Iodogen method. The final 125I?SPIO?HAbF18(ab')2 nanoprobes were purified. SPIOs or 125I?HAb18F(ab')2 were used as control. We carried preliminary evaluation on their physicochemical properties and biological characteristics in vitro: transmission electron microscope (TEM) and dynamic light scattering (DLS) were used to measure these nanoparticle sizes and the hydrodynamic diameters. The MRI T2 transverse relaxation efficiency of these nanoprobes at different Fe2+concentrations were measured with 1.5 T clinical MR scanner. The 125I?SPIO?HAb18F(ab')2 and 125I?HAb18F(ab')2 radiochemical purity were measured by thin layer chromatography and the radio chemical yield was calculated. We also conducted stability tests in vitro and octanol/water partition coefficient experiments. Two breast tumor cell lines, MDA?MB?231 (HAb18G?overexpressing cells,experimental group) and MDA?MB?468 (control), were used for assessment of cells viability at different Fe2 + concentrations (1, 5, 10, 20, 40 μg/ml) by methyl thiazolyl tetrazolium assay. Specific binding experiments in vitro included two parts:magnetic resonance imaging and radionuclide tests, the above?mentioned breast cancer cell lines were incubated with 125I?SPIO?HAb18F(ab')2 nanoprobes respectively and took MDA?MB?231 cells which were not treated as blank group. First comparing the MR signal intensity differences among experimental group, the control group and blank group, then calculated the rate of MRI signal changes;Two breast tumor cell lines, MDA?MB?231 and MDA?MB?468 were incubated with 125I?SPIO?HAb18F(ab')2 nanoprobes too, then measured radioactivity counting byγcounter at different time and calculated the cell binding rates, and did statistical analysis by using one?way ANOVA. Results The SPIOs were fairly homogeneous with an average core size of (10.32±1.30) nm;the SPIO and 125I?SPIO?HAb18F(ab')2 hydrodynamic diameter of 44.80 and 52.64 nm, and MRI scanning showed that the transverse relaxation efficiency of SPIO and 125I?SPIO?HAb18F(ab')2 were 38.79 and 106.73 mM-1 · s-1, respectively. The radio chemical yield of 125I?SPIO?HAbF18(ab')2 and 125I?HAb18F(ab')2 were 41.90% and 85.50%, respectively. The radio chemical yield of the two groups were >95%, suggesting well stability in vitro. The lipo?hydro partition coefficient values were -0.99 ± 0.03 and-1.49 ± 0.08, respectively, which demonstrated that they were both water?soluble substances. Different Fe2+concentrations (1,5,10,20,40μg/ml) of 125I?SPIO?HAb18F(ab')2 on breast cancer cell lines MDA?MB?231 and MDA?MB?468 showed no significant inhibition of cell proliferation (F values were 0.78, 0.66; P values were 0.58, 0.66). The cell?specific binding experiment showed: MRI signal intensity values on experimental group, the control group and the blank group were (1 670 ± 5), (1 930 ± 8), (2 349 ± 14), respectively, significant differences existed among these groups (F=4 408.48,P=0.000), the rate of signal intensity change of experimental group and the control group were 28.87%,17.78%. SPECT:MDA?MB?231 could uptake 125I?SPIO?HAb18F(ab')2, the cell binding rates were (6.52 ± 0.60)% and (10.52 ± 2.04)% in 20 min and 4 h, respectively.Conclusions Our results suggested that the dual?modality SPECT?MRI nanoprobes 125I?SPIO?HAb18F(ab')2 were prepared successfully with good physicochemical properties and biological characteristics in vitro. These dual?modality molecular imaging nano?probes may have potential to improvearly detection and diagnosis of HAb18G/CD147?expressing cancers and to facilitate the development of HAb18G/CD147?directed interventions.

ObjectiveTo establish a novel assay for HIV-1 p24 ultrasensitive detection based on Gold Nanoparticle Probe (GNP) and PCR.MethodsSandwich ELISA method was established by a pair of anti-p24 monoclonal antibodies (mAbs),1G12 and 1D4,and was used to detect recombinant HIV-1 p24 antigen.The bio-barcode DNA was 47 bp,selected from genome of Arabidopsis,and formed double-stranded DNA by hybridization with the capture DNA (complementary with bio-barcode DNA) modified with sulfhydryl.Then double-stranded DNA were conjugated on the surface of 1D4-modified gold nanoparticles by sulfhydryl,and the Gold Nanoparticle Probe was produced.1G12 was precoated in the micropaltes,and in the presence of target recombinant HIV-1 p24 protein,a sandwich immuno-complex would form by adding GNP.Then the bio-barcode DNA in the immuno-complex were released by heating as detection signal,and consequently characterized by the polymerase chain reaction (PCR) with synthesized special primers and analyzed by 4％ agar gel electrophoresis,so HIV-1 p24 antigen could be evaluated.The sensitivity comparison between the new assay and ELISA can be done.ResultsSandwich ELISA was used to quantify HIV-1 p24 antigen by monoclonal antibodies 1G12 and 1D4,and the limit of detection (LOD) was 1000 pg/ml.The new GNP assay was established by the same pair of antibodies,combined with PCR and agar gel electrophoresis,and was used to indirectly detect HIV-1 p24 antigen.The band intensity of PCR products paralleled with the quantity of HIV-1 p24 antigen,and the limit of detection (LOD) could reach down to 1 pg/ml.ConclusionThe new assay based on GNP and PCR was efficient in the detection of HIV-1 p24,which is at least 3 orders of magnitude more sensitive than traditional ELISA.