Carriers are equally important as drugs. They can substantially improve bioavailability of cargos and safeguard healthy cells from toxic effects of certain therapeutics. Recently, polymeric nanocarriers (PNCs) have achieved significant success in delivering drugs not only to cells but also to subcellular organelles. Variety of natural sources, availability of different synthetic routes, versatile molecular architectures, exploitable physicochemical properties, biocompatibility, and biodegradability have presented polymers as one of the most desired materials for nanocarrier design. Recent innovative concepts and advances in PNC‐associated nanotechnology are providing unprecedented opportunities to engineer nanocarriers and their functions. The efficiency of therapeutic loading has got considerably increased. Structural design‐based varieties of PNCs are widely employed for the delivery of small therapeutic molecules to genes, and proteins. PNCs have gained ever‐increasing attention and certainly paves the way to develop advanced nanomedicines. This article presents a comprehensive investigation of structural design‐based varieties of PNCs and the influences of their physicochemical properties on drug delivery profiles with perspectives highlighting the inevitability of incorporating both the multi‐stimuli‐responsive and multi‐drug delivery properties in a single carrier to design intelligent PNCs as new and emerging research directions in this rapidly developing area.

Ferroelectric BaTiO₃ became a multifunctional material via doping of lanthanide ions (0.3 mol% Er³⁺/3.0 mol% Yb³⁺) and subsequently upconversion luminescence was enhanced by incorporation of Zn²⁺ ions. Upconversion luminescence of BaTiO₃:Er³⁺/Yb³⁺ perovskite nanophosphor has been studied using 800 and 980 nm laser excitations. The emission dynamics is studied with respect to its dependence on input power and external temperature including lifetime. Based on time-resolved spectroscopy, it is inferred that two types of Er³⁺ sites are present in the barium titanate lattice. The first one is a short lived component (minor species) present at 6-coordinated Ti-sites of low symmetry while the second one is a long lived component (major species), present at 12-coordinated Ba-sites with high symmetry. The influence of the introduction of Zn²⁺ ions on the lifetime of ⁴S_3/2 and ⁴F_9/2 levels of Er³⁺ ions is also investigated. Enhanced temperature sensing performance (120 K to 505 K) of the material is observed using the fluorescence intensity ratio technique, employing the emission from the thermally coupled, ²H_11/2 and ⁴S_3/2 energy levels of Er³⁺ ions. The defect luminescence of the material is also found to increase upon Zn-doping.

Enhancing upconversion, temperature sensing and cathodoluminescence in the CaMoO ₄ :Er ³⁺ /Yb ³⁺ nanophosphor via K ⁺ /Na ⁺ simultaneous codoping.