Polydopamine Modified Biosilica for Purification of Heavy Metal-Polluted Water

Abstract

Water pollution by aqueous heavy metals has become one of the most serious environmental problems nowadays. The purification of polluted water is of special concern due to toxicity of heavy metals on human health. For removal of heavy metal ion, adsorption technique is very popular because of simplicity and low cost. In recent years, there were several previous studies using non-living algal biomass as an adsorbent for the elimination of heavy metals due to its advantages such as low cost and easy cultivation. Diatoms are photosynthetic algae, found in the oceans, which have cell wall, called frustule. Diatom frustule, which has porous structure and high surface area, can exhibit enhanced heavy metal ion adsorption capacity with absence of secondary pollutants and low cost.

Polydopamine has been used for removal of heavy metal ion due to its chelating ability and simple depositing method without any surface pretreatment. However, substrates that were used in studies of elimination of heavy metal ions using polydopamine coating have problems such as high cost and production of secondary pollutants.

In chapter 1, nature-originated diatom frustule powders modified with a mussel-inspired adhesive, polydopamine, have been studied as an adsorbent for aqueous heavy metals. Diatom frustule powder, processed diatom, was coated by polymerization of dopamine hydrochloride. An aqueous solution containing heavy metal ions was passed through the column and the removal of heavy metal ions in eluate was confirmed by inductively coupled plasma-mass spectrometry.

Atopic dermatitis is a skin disease accompanied by itching, red rash, and dry skin, which is one of the most common disease. Typical treatments for atopy have side effects including diabetes, osteoporosis, and hypertension. Recently, sacran which is another algal biomass, has attracted a particular focus of attention as a new material for atopy treatment, which is a sulfated glycosaminoglycan-like compound extracted from river algae Aphanothece sacrum. Previous studies showed that sacran is effective in the treatment of atopic dermatitis due to its anti-inflammatory effect and moisturizing effect. However, huge molecular weight of sacran (~16 MDa) makes transdermal delivery difficult.

In chapter 2, we increased transdermal delivery efficiency of sacran by using dissolving microneedle (MN) patches. Dissolving microneedles for transdermal delivery of sacran are fabricated using droplet-born air blowing (DAB) method with the advantage of minimization of drug deformation and drug loss. It was confirmed that dissolving MN patches containing sacran helped relieve atopic symptoms through in-vivo test