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Near infrared (NIR) fluorophores like Pt-porphyrin along with analyte specific enzymes require co-encapsulation in biocompatible and biodegradable carriers in order to be transformed into implantable biosensors for efficient and continuous monitoring of analytes in patients. The main objective of this research is to develop natural, biodegradable, biocompatible and a novel co-encapsulated system of Pt-porphyrin encapsulated polymeric nanoparticle and nano-micro hybrid carriers. A sequential emulsification-solvent evaporation and an air driven atomization technique was used for developing above matrices and testing them for fluorescence based oxygen and glucose biosensing. The results indicate Pt-porphyrin can be efficiently encapsulated in Poly-lactic acid (PLA) nanoparticles and PLA-alginate nano-micro particles with sizes ~450 nm and 10 µm, respectively. Biosensing studies have showed a linear fluorescent response in oxygen concentrations ranging from of 0–6 mM (R2 = 0.992). The Oxygen sensitivity was transformed into a linear response of glucose catalytic reaction in the range of 0–10 mM (R2 = 0.968) with a response time of 4 minutes and a stability over 15 days. We believe that the investigated NIR fluorophores like Pt-Porphyrin based nano/nano-micro hybrid carrier systems are novel means of developing biocompatible biodegradable carriers for developing implantable glucose biosensors which can efficiently manage glucose levels in diabetes.

This research demonstrates a carbon quantum dot (CQD) based fluorescence technique for milk quality assessment and detection of urea adulteration using a commercialized optical fiber spectrometer (OFS) and a developed color sensor device (CSD). The change in pH from the normal pH of milk (∼6.7) indicates spoilage. The CQDs were synthesized using phthalic acid (carbon source) and triethylenediamine (TED) (passivant). The CQDs were found to be sensitive in the pH range 3−10 with a quantum yield of about 18.9%. The accuracy of spoilage detection using CQDs was expressed in the form of mean percent recovery and found to be 99.2% (R 2 = 0.97) by the OFS and 99.59% (R 2 = 0.98) by the CSD. The mean percent recovery obtained for urea adulteration in milk was 103.0% (R 2 = 0.98) by the OFS and 97.9% (R 2 = 0.97) by the CSD. The results indicate that CQDs have excellent potential for use as biosensors for spoilage and adulteration detection.

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