Detection of prostate specific antigen (PSA) in human saliva using an ultra-sensitive nanocomposite of graphene nanoplatelets with diblock-co-polymers and Au electrodes.

Prostate-specific antigen (PSA) is a commonly used biomarker for the detection of prostate cancer (PCa) and there are numerous data available for its invasive detection in the serum and whole blood. In this work, an electrochemical sensing method was devised to detect traces of PSA in human saliva using a hybrid nanocomposite of graphene nanoplatelets with diblock co-polymers and Au electrodes (GRP-PS67-b-PAA27-Au). The pure graphitic composition on filter paper provides significantly high electrical and thermal conductivity while PS67-b-PAA27 makes an amphiphilic bridge between GRP units. The sensor utilizes the binding of an anti-PSA antibody with an antigen-PSA to act as a resistor in a circuit providing an impedance change that in turn allows for the detection and quantification of PSA in saliva samples. A miniaturized electrical impedance analyzer was interfaced with a sensor chip and the data were recorded in real-time using a Bluetooth-enabled module. This fully integrated and optimized sensing device exhibited a wide PSA range of detection from 0.1 pg mL-1 to 100 ng mL-1 (R2 = 0.963) with a lower limit of detection of 40 fg mL-1. The performance of the biosensor chip was validated with an enzyme-linked immunosorbent assay technique with a regression coefficient as high as 0.940. The advantages of the newly developed saliva-PSA electrical biosensor over previously reported serum-PSA electrochemical biosensors include a faster response time (3-5 min) to achieve a stable electrical signal for PSA detection, high selectivity, improved sensitivity, no additional requirement of a redox electrolyte for electron exchange and excellent shelf life. The presented sensor is aimed for clinical commercialization to detect PSA in human saliva.

Renal prostaglandins in renal hypertensive dogs.

1. Hypertension produced in two-kidney Goldblatt dogs was accompanied by a transient fluid retention, reaching a maximum 4 days after clamping. 2. Prostaglandin E and F concentrations in venous blood from the intact kidney also rose transiently, showing a maximum by the fifth day. 3. The rise in prostaglandin release from the intact kidney may be related to the fluid retention.

Renal blood flow autoregulation and renal venous prostaglandins in the pump-perfused canine kidney (in situ).

1. Renal autoregulation of blood flow was re-examined in the pump-perfused canine kidney and concentrations of prostaglandins E and F in the renal venous plasma were measured by radioimmunoassay. 2. At low perfusion pressures, below the range of autoregulation, prostaglandin E and F concentrations rose and calculated prostaglandin E secretion rate fell. 3. Meclofenamate (10 mg/kg i.v.) reduced renal blood flow and prostaglandin E and F secretion rates, but did not abolish autoregulation. 4. Renal prostaglandins do not appear to mediate autoregulation in the kidney but may affect the level at which flow is controlled.

The development of antisera to prostaglandins B2 and F2alpha and their analysis using solid-phase and double antibody radioimmunoassay methods.

1 A method for the production of highly substituted prostaglandin-bovine serum albumin conjugates has been developed. 2 Antisera to prostaglandins B2 and F2alpha were raised in rabbits immunized with prostaglandin-bovine serum albumin conjugates. 3 The antisera were assessed for specificity and sensitivity by the double antibody radioimmunoassay method and after they were covalently linked to powdered cellulose to form a 'solid-phase' system. 4 Solid phase radioimmunoassays were developed using conventional shaking and in the presence of sucrose which obviates the need for continuous mixing of the incubates.

A solid-phase radioimmunoassay for plasma progesterone.

A detailed procedure is presented for the assay of plasma progesterone. The routine assay is based on the use of antiserum which is covalently linked to microcrystalline cellulose, the double-antibody method being used as a reference separation system. This procedure gives high precision accompanied by small and acceptable losses of antiserum titre but without loss of sensitivity when compared with the double-antibody method. Ethanol is first added to the plasma (10vol. of plasma+1vol. of ethanol) after which a single extraction with light petroleum yields a constant recovery [92.4+/-1.2 (s.d.)% of added [(3)H]progesterone] and obviates the need for tracer recoveries on each sample being assayed. Distortions of the response curve owing to solvent residues have been almost eliminated. The assay can measure progesterone at all stages of the menstrual cycle when volumes of 200mul of plasma are used and this permits the detection of the periovulatory rise at its inception. Detailed specificity studies are presented for the assay end point itself and these are related to the responses to be expected in extracts of plasma. Progesterone-like activity was found in urine and a fourfold increase in excretion rates was observed between the follicular and luteal phase of the normal menstrual cycle.