Organic and inorganic nanoparticles (NPs) have shown promising outcomes in transdermal drug delivery. NPs can not only enhance the skin penetration of small/biomacromolecule therapeutic agents but can also impart control over drug release or target impaired tissue. Thanks to their unique optical, photothermal, and superparamagnetic features, NPs have been also utilized for the treatment of skin disorders, imaging, and biosensing applications. Despite the widespread transdermal applications of NPs, their delivery across the stratum corneum, which is the main skin barrier, has remained challenging. Microneedle array (MN) technology has recently revealed promising outcomes in the delivery of various formulations, especially NPs to deliver both hydrophilic and hydrophobic therapeutic agents. The present work reviews the advancements in the application of MNs and NPs for an effective transdermal delivery of a wide range of therapeutics in cancer chemotherapy and immunotherapy, photothermal and photodynamic therapy, peptide/protein vaccination, and the gene therapy of various diseases. In addition, this paper provides an overall insight on MNs’ challenges and summarizes the recent achievements in clinical trials with future outlooks on the transdermal delivery of a wide range of nanomedicines.

RNA therapeutics, such as mRNA, siRNA, and CRISPR–Cas9, present exciting avenues for treating diverse diseases. However, their potential is commonly hindered by vulnerability to degradation and poor cellular uptake, requiring effective delivery systems. Lipid nanoparticles (LNPs) have emerged as a leading choice for in vivo RNA delivery, offering protection against degradation, enhanced cellular uptake, and facilitation of endosomal escape. However, LNPs encounter numerous challenges for targeted RNA delivery in vivo, demanding advanced particle engineering, surface functionalization with targeting ligands, and a profound comprehension of the biological milieu in which they function. This review explores the structural and physicochemical characteristics of LNPs, in-vivo fate, and customization for RNA therapeutics. We highlight the quality-by-design (QbD) approach for targeted delivery beyond the liver, focusing on biodistribution, immunogenicity, and toxicity. In addition, we explored the current challenges and strategies associated with LNPs for in-vivo RNA delivery, such as ensuring repeated-dose efficacy, safety, and tissue-specific gene delivery. Furthermore, we provide insights into the current clinical applications in various classes of diseases and finally prospects of LNPs in RNA therapeutics.

In the past decade, miRNAs have been extensively attracted the scientist’s attentions as tumor suppressors or oncogenes that have been implicated in tumor progression, metastasis and intrinsic resistance to various cancer therapies. microRNA-21 (miR-21) demonstrates a potential oncogenic function and targets tumor inhibitor proteins in almost all types of cancer. miR-21 overexpression has been studied in terms of cell proliferation, migration, invasion, metastasis, and apoptosis regulation. Inhibition of miRNA expression using antisense technology by various nanovectors of different sizes, shapes and compositions has been evolved progressively to overcome the barriers confronted by miRNA delivery. Application of miR-21 antisense oligonucleotides for treating cancerous cells has become a promising achievement for cancer therapy. Moreover, miR-21 can mediate resistance to radiation and chemotherapy. The expanding role of miR-21 functions in human cancers with an emphasis on its regulatory targets and mechanisms, miR-21 related achievements against cancer promotion have been discussed.