Noninvasive Prenatal Genetic Screening of Cell-Free Fetal DNA for Early Prediction of ß-Thalassemia Using Fiber Optic Nanogold-Linked Sorbent Assay.

ß-Thalassemia is a prevalent type of severe inherited chronic anemia, primarily identified in developing countries. The identification of single nucleotide polymorphisms (SNPs) plays a vital role in the early diagnosis of genetic diseases. Here, we reported the development of an amplification-free fiber optic nanogold-linked sorbent assay method using a fiber optic particle plasmon resonance (FOPPR) biosensor for rapid and ultrasensitive detection of SNPs. Herein, MutS protein was selected as the biorecognition capture probe and immobilized on the sensing region to capture the target mutant DNA, which was hybridized with a single-base mismatched single-stranded DNA labeled by a gold nanoparticle (AuNP). The AuNP acts as a signaling agent to be detected by the FOPPR biosensor when it is bound on the fiber core surface. The method effectively differentiates mismatched double-stranded DNA by MutS protein from perfectly matched/complementary dsDNA. It exhibits an impressively low detection limit for the detection of SNPs at approximately 10-16 M using low-cost sensor chips and devices. By determination of the ratio of mutant DNA to normal DNA in cell-free genomic DNA from blood samples, this method is promising for diagnosing ß-thalassemia in fetuses without invasive testing techniques.

Competitive Assay for the Ultrasensitive Detection of Organophosphate Pesticides Based on a Fiber-Optic Particle Plasmon Resonance Biosensor and an Acetylcholinesterase Binding Peptide.

An acetylcholinesterase (AChE) binding-based biosensor was developed for the ultrasensitive detection of organophosphate (OP) pesticides. The biosensor integrates the technique based on fiber-optic particle plasmon resonance detection and a synthetic AChE binding peptide conjugated with gold nanoparticles on the optical fiber surface via an AChE competitive binding assay. The OP pesticides present in the solution hinder the binding of AChE to the peptide on the biosensor by competing for the binding sites present in AChE. The limit of detection obtained for parathion using this method was observed to be 0.66 ppt (2.3 pM). This method shows a wide linear dynamic range of 6 orders. Furthermore, the use of the AChE binding peptide in the biosensor can better discriminate OPs against carbamates by using only a single biosensor. The practical application of this method was tested using spiked samples, which yielded good recovery and reproducibility. The spiked sample required minimal pretreatment before analysis; hence, this biosensor may also be used in the field.

A fiber optic nanoplasmonic biosensor for the sensitive detection of ampicillin and its analogs.

A novel optical immunosensor for the screening of ampicillin (Amp) residues has been developed. The biosensor is based on fiber optic particle plasmon resonance detection and uses an enhancement method called as fiber optic nanogold-linked immunosorbent assay (FONLISA) for the sensitive detection of antibiotics. A commercial antibody which had a higher affinity for ampicillin than for other ß-lactam antibiotics was chosen. A surface competitive binding assay was used in which a fixed concentration of antibiotic-conjugated gold nanoparticles (AuNPs) competes with free unlabeled antibiotic molecules to measure the amount of binding with antibody molecules immobilized on an optical fiber. The synthesis of the 11-mercaptoundecanoic acid (MUA)-ampicillin conjugate facilitates the attachment of the Amp molecules to AuNPs via MUA which acts as a linker between them. This AuNP-Amp conjugate was then used for the detection of ß-lactam antibiotics. The practical limit of detection obtained for Amp was 0.74 ppb (7.4 × 10-10 g/mL) which is lower than the recommended maximum residue limit (MRL) for ß-lactams. The method also shows a wide linear range of 4 orders. Its applicability to the determination of ampicillin in spiked milk samples has been demonstrated with good recovery and reproducibility. Graphical abstract.

Formulation and evaluation of multiparticulate system for chronotherapeutic delivery of salbutamol sulphate.

Solution layering technique was used to prepare pellets of Salbutamol Sulphate. A multiparticulate system was prepared with pH independent and pH dependent coatings, and evaluated as pulsatile drug delivery system. Salbutamol sulphate release was studied from methacrylate coated pellets from non pareils. Morphology was studied using Scanning Electron Microscopy for the characterization of prepared pellets. Combination of Eudragit RSPO (pH independent) and Eudragit L100 (pH dependent) was used for coating of the pellets. Different concentrations of this polymeric combination were loaded on to the drug-loaded pellets. The aim of this study was to investigate the effect of physicochemical properties of the polymers on the release profile of Salbutamol sulphate from the pellets dosage form. The in-vitro study suggested that Eudragit RSPO and Eudragit L100 at 10% coating level led to an optimum pulsatile release behavior. The coated pellets prepared by solution layering technology successfully released drug after specific lag time indicating pulsatile drug delivery. It was revealed that Eudragit RSPO has the effect to retard drug release. The results generated in this study showed that proper selection of polymeric materials based on their physicochemical properties is important in designing pellets dosage form with suitable dissolution profile.