Applications of capillary action in drug delivery

Abstract

Contrary to the fact that capillary action is ubiquitous in our daily lives, its role in drug delivery has not attracted attention. Therefore, its application in medicine and disease treatment has not been actively developed. This perspective begins by reviewing the principles, advantages, and limitations of the three existing drug delivery strategies: non-covalent interaction, cavity loading, and covalent conjugation. Then, we discussed the principle of capillary action in drug delivery and the influencing factors that determine its performance. To illustrate the advantages of capillary action over existing drug delivery strategies and how the capillary action could potentially address the shortcomings of the existing drug delivery strategies, we described five examples of using capillary action to design drug delivery platforms for disease treatment: marker pen for topical and transdermal drug delivery, microneedle patch with a sponge container for pulsatile drug delivery, core-shell scaffold for sustained release of growth factors, oral bolus for insulin delivery to the esophagus, and semi-hollow floating ball for intravesical and gastroprotective drug delivery. Each of the five drug delivery platforms exhibits certain unique functions that existing drug delivery technologies cannot easily achieve, hence expected to solve specific practical medical problems that are not satisfactorily resolved. As people pay more attention to capillary action and develop more drug delivery platforms, more unique functions and characteristics of capillary action in drug delivery will be explored. Thus, capillary action could become an important choice for drug delivery systems to improve therapeutic drug efficacy, treat diseases, and improve human health.

Dual Catalytic and Self‐Assembled Growth of Two‐Dimensional Transition Metal Dichalcogenides Through Simultaneous Predeposition Process

“…Although metal organic salts, such as perylene‐3,4,9,10‐tetracarboxylic acid tetrapotassium salts, were introduced in early CVD studies [ 9,25 ] remarkable improvements in growth have been demonstrated by the adoption of alkali metal halides (AMHs). [ 26–38 ] The versatility and practicality of AMH‐assisted CVD are supported by the reduced process temperature, [ 26 ] millimeter‐scaled large grains, [ 27 ] rapid growth, [ 27,28 ] and one‐dimensional growth (TMD nanowire). [ 29 ] AMH‐assisted CVD has evolved into a universal process capable of synthesizing more than 40 2D TMDs.…”

Hydration‐Induced Void‐Containing Hydrogels for Encapsulation and Sustained Release of Small Hydrophilic Molecules

“…In recent decades, hydrogels have been widely used as drug delivery vehicles due to their excellent biocompatibility, storage, this can result in depletion of the vehicles' drug content; concerning in vivo, this can manifest as burst release and systemic toxicity, which is especially problematic with ultrapotent drugs. [12][13][14][15] Given the advantages of hydrogels in biomedical engineering applications, if the above challenges of small hydrophilic molecule delivery are addressed, hydrogels could have an extensive clinical impact on the local delivery of small hydrophilic molecules.…”

Hybrid Alkali Salt Catalysts‐Promoted CVD Growth of 2D MoSe2–WSe2 and WSe2–MoSe2 Lateral Heterostructures

“…[ 17,18 ] To solve this problem, alkali metal halide‐based catalysts are commonly used to accelerate the growth of CVD 2D materials. [ 19 ] The role of cations (Na + , Li + , K + ) and anions (F − , Cl − , Br − , I − ), [ 20,21 ] and the use of single salt catalysts have been widely explored. [ 19,22–26 ] The metal halide catalysts offer two intermediate products including volatile metal oxyhalides and non‐volatile molten metals, assisting the nucleation growth's kinetics and thermodynamics.…”

“…[ 19 ] The role of cations (Na + , Li + , K + ) and anions (F − , Cl − , Br − , I − ), [ 20,21 ] and the use of single salt catalysts have been widely explored. [ 19,22–26 ] The metal halide catalysts offer two intermediate products including volatile metal oxyhalides and non‐volatile molten metals, assisting the nucleation growth's kinetics and thermodynamics. [ 20 ] In addition, dual additive catalysts with core precursor embedded – Na 2 MoO 4 –Na 2 SeO 3 have been introduced through a molten metal droplet growth pathway, resulting in a continuous growth of MoSe 2 monolayers.…”