Targeting nanoparticle (NP) carriers to sites of disease is critical for their successful use as drug delivery systems. Along with optimization of physicochemical properties, researchers have focused on surface modification of NPs with biological ligands. Such ligands can bind specific receptors on the surface of target cells. Furthermore, biological ligands can facilitate uptake of modified NPs, which is referred to as ‘active targeting’ of NPs. In this review, we discuss recent applications of biological ligands including proteins, polysaccharides, aptamers, peptides, and small molecules for NP-mediated drug delivery. We prioritized studies that have demonstrated targeting in animals over in vitro studies. We expect that this review will assist biomedical researchers working with NPs for drug delivery and imaging.

Nanoparticles (NPs) play a key role in nanomedicine in multimodal imaging, drug delivery and targeted therapy of human diseases. Consequently, due to the attractive properties of NPs including high stability, high payload, multifunctionality, design flexibility, and efficient delivery to target tissues, nanomedicine employs various types of NPs to enhance targeting and treatment efficacy. In this review, we primarily focus on light-responsive materials, such as fluorophores, photosensitizers, semiconducting polymers, carbon structures, gold particles, quantum dots, and upconversion crystals, for their biomedical applications. Armed with these nanomaterials, NPs represent a growing potential in biophotonic imaging (luminescence, photoacoustic, surface enhanced Raman scattering, and optical coherence tomography) as well as targeted therapy (photodynamic therapy, photothermal therapy, and light-responsive drug release).

BackgroundClick chemistry is termed as a group of chemical reactions with favorable reaction rate and orthogonality. Recently, click chemistry is paving the way for novel innovations in biomedical science, and nanoparticle research is a representative example where click chemistry showed its promising potential. Challenging trials with nanoparticles has been reported based on click chemistry including copper-catalyzed cycloaddition, strain-promoted azide-alkyne cycloaddition, and inverse-demand Diels-Alder reaction.Main bodyHerein, we provide an update on recent application of click chemistry in nanoparticle research, particularly nanoparticle modification and its targeted delivery. In nanoparticle modification, click chemistry has been generally used to modify biological ligands after synthesizing nanoparticles without changing the function of nanoparticles. Also, click chemistry in vivo can enhance targeting ability of nanoparticles to disease site.ConclusionThese applications in nanoparticle research were hard or impossible in case of traditional chemical reactions and demonstrating the great utility of click chemistry.

This review summarizes recent advances in the development of nanoparticles (NPs) for efficient photodynamic therapy (PDT), particularly the development and application of various NPs based on organic and inorganic materials. PubMed database was used for literature search with the terms including NP, nanomedicine, PDT, photosensitizer (PSs), and drug delivery. For successful PDT, it is essential to deliver PSs to target disease sites. A number of NPs have been developed and tested as the carriers for both imaging and therapy, an approach termed "nanomedicine". Many studies of NP carriers showed increased water solubility and stability of PSs for injection, and these NP carriers provided benefits including longer circulation in blood and higher accumulation of PSs at disease sites. This review describes new techniques in PDT such as aggregation-induced emission (AIE) and luminescence-based PDT, and provides insights on NPs and PDT for biomedical researchers working to develop or apply NPs in efficient PDT.

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