Cyclodextrins and their derivatives play an important role in improving the therapeutic efficacy of drugs with poor solubility and/or stability problems. They are capable of alleviating the undesirable properties of drug molecules through the formation of inclusion complexes (1). Hydroxypropyl-b-cyclodextrin (HPbCD) is mainly selected for its higher solubility than other cyclodextrins and this generally results in more extensive solubilization ability toward lipophilic molecules, with a good safety profile (2). Ternary complexes of meloxicam (ME) (a poorly water soluble anti-inflammatory drug) with hydroxypropyl-b--cyclodextrin (HPbCD) and either a hydrophilic polymer, namely, polyvinyl pyrrolidone (PVP) or a basic amino acid such as L-arginine, were prepared by the spray-drying technique. The solubilizing efficiency, physical properties and dissolution behaviour of each ternary system of ME--HPbCD with either PVP or L-arginine were compared with those of the corresponding binary system of ME--HPbCD. Tablets compressed from the ternary system of ME-HPbCD-L-arginine were compared with plain and commercial tablets. Phase solubility experiments suggested the formation of an inclusion complex of A L type. Ternary system of ME-HPbCD-L-arginine exhibited a stability constant 30.3 times higher than the binary system of ME-HPbCD, while the ternary system of ME-HPbCD--PVP increased the stability constant 2.2 times only. The prepared complexes were characterized by scanning electron microscopy, differential scanning calorimetry and infra red spectroscopy. Ternary solid complexes indicated the presence of strong interactions between the components. The dissolution behaviour of ME from different ternary complexes was higher than its dissolution from the binary system. Tablets compressed from ternary complexes of ME-HPbCD-L-arginine highly improved drug release compared to plain and commercial tablets.

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Semiconductor quantum dots (QDs) offer tremendous scope to be used in the field of energy, imaging, sensors and optoelectronic devices. However, several issues regarding their hydrophilicity, stability and cytotoxicity remain unresolved. One of the methods to render CdTe QDs water-soluble is to functionalize the surface with carboxylate groups by the use of heterobifunctional ligands such as 3-mercaptopropionic acid (MPA). Following this motif, we report the synthesis of CdTe QDs using the non-aqueous organometallic route, ligand exchange with MPA was performed to replace the initial surface passivation ligands trioctylphosphine oxide (TOPO) and hexadecylamine, and finally, the prepared MPA-CdTe QDs were encapsulated into the biocompatible polyethylene glycol. Our results show that pegylation of CdTe QDs provided minimal cytotoxicity against baby hamster kidney (BHK 21) cells even at high levels. The IC 50 values of pegylated CdTe QDs were higher than the non-pegylated ones with a % viability ranges from 89:90% at a concentration range of 0.01:0.03 nM. Currently, available ligand exchange procedures lead to significant loss of quantum yields. In our study, the photoluminescence (PL) emission of the MPA capped CdTe QDs decreased gradually as the pH increased from 4 to 10 while after pegylation the prepared QDs exhibited significantly enhanced PL efficiency and storage stability.

Water-soluble semiconductor quantum dots (QDs) have become a unique field of materials science with great potential for applications in biomedical and optoelectronic devices. However, the more stable and bright QDs are the conventional QDs that contain toxic heavy metals such as Pb, Cd and Hg or the QDs that were synthesized in an organic phase. Hence, it is important to find an alternative material with similar optical properties and low cytotoxicity among these materials. Recently, hydrophilic CuInS2 (CIS) QDs have attracted a lot of interest due to their direct bandgap in the infrared region, large optical absorption coefficient, hydrophilicity, low cost and low toxic composition. These factors make them a good material for biomedical applications. This review starts with the origin characteristics of CIS QDs followed by various synthetic strategies, including synthesis in aqueous solvents and transformation from organic phase to water-soluble phase QDs. Then the tuning of their optical properties is discussed. The review then considers the strategies to improve the photoluminescence performances of CIS QDs.

Quantum dots (QDs), a type of semiconductor nanomaterial, have drawn a lot of attention because of their exceptional optical characteristics and prospective uses in biology and medicine. However, the presence of heavy hazardous metals in typical QDs, such as Cd, Pb and Hg, has posed a significant obstacle to their use. Therefore, it is essential to look for a workable substitute that would be nontoxic and have comparable optical characteristics to the traditional QDs. It has been determined that ternary I–III–VI QDs are appropriate substitutes. They emit light in the near-infrared range and have adjustable optical characteristics. They are valuable in a variety of biological applications because of their optical characteristics and can be easily bioconjugated with biomolecules for targeted imaging. Therefore, this review concentrates on the most recent developments in the usage of aqueous CIS QDs in biological, bioconjugated with biomolecules, nanomedical and drug delivery system applications.