Hydrophobically-modified poly(vinyl pyrrolidone) as a physically-associative, shear-responsive ophthalmic hydrogel

Sheikholeslami, Paniz; Muirhead, Ben B; Baek, David Sung Hyeon; Wang, Hai; Zhao, Xu; Sivakumaran, Daryl; Boyd, Shelley; Sheardown, Heather; Hoare, Todd

doi:10.1016/j.exer.2015.05.021

Cited by 26 publications

(16 citation statements)

References 48 publications

(46 reference statements)

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“…The reasons for the coagulation of slurries dispersed by hydrophobic dispersants are as follows. (a) The particles are bridged because of the attractive force between the hydrophobic chains of the dispersant, resulting in coagulation 42‐44 . (b) The introduction of TMAC may have added ions in the slurry, causing the compression of the electrical double layer and resulting in the flocculation of the slurry 39,40,45 …”

Section: Resultsmentioning

confidence: 99%

“…(a) The particles are bridged because of the attractive force between the hydrophobic chains of the dispersant, resulting in coagulation. [42][43][44] (b) The introduction of TMAC may have added ions in the slurry, causing the compression of the electrical double layer and resulting in the flocculation of the slurry. 39,40,45 In order to understand which of the above reasons dominated the coagulation of the slurries, we carried out a comparative testing by separately adding KCl and TMAC to the ceramic slurries (0.3 wt% Isobam 600AF; 50 vol% solid loading) and controlling the same ion concentration.…”

Section: Rheological Behavior Of Slurriesmentioning

confidence: 99%

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Hydrophobic coagulation of alumina slurries

et al. 2020

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Wet forming 1,2 is an important ceramic forming technology, characterized by the transformation of slurry (suspension) to wet body. Based on the coagulation mode, wet forming can be divided into two types: (a) obtaining wet body through solidliquid separation, including slip casting, 3 pressure filtration, 4 tape casting, 5 and centrifugal molding 6 and (b) obtaining wet body through in-situ coagulation of slurry, including polymer additive transformation (agarose 7 and gelatin 8), gel casting, 9,10 and direct coagulation casting (DCC). 11 Wet bodies formed by in-situ coagulation do not have the gradient problem caused by solid-liquid separation but usually require kinds of additives to achieve coagulation. In addition, an inducer (temperature, pH value, or initiator, etc) is needed to trigger the slurry state change, which increases the technical difficulty in practical operations. Recently, Yang et al 12 reported the spontaneous coagulation casting (SCC) method in which PIBM (a copolymer of isobutylene and maleic anhydride; commercial name,

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Section: Resultsmentioning

confidence: 99%

Section: Rheological Behavior Of Slurriesmentioning

confidence: 99%

Hydrophobic coagulation of alumina slurries

et al. 2020

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“…For this study, institutional animal ethical clearance was taken vide permission #36/IAEC‐IPT/18, dated 9/5/2018. In vivo ocular irritation test was conducted as per the Draize rabbit eye test protocol . In gist, 0.1 g of the prepared oleogels was placed within the conjunctival sac of the right eye of an albino rabbit.…”

Section: Methodsmentioning

confidence: 99%

Oleogels Based on Palmitic Acid and Safflower Oil: Novel Formulations for Ocular Drug Delivery of Voriconazole

Mohanty¹,

Pal

Quereshi

et al. 2020

Euro J Lipid Sci & Tech

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The gelation of the vegetable oils using fat crystals has gained significant attention in recent years. These formulations have been explored for food and pharmaceutical applications. The alteration in the properties of palmitic acid (20–40% w/w) and safflower oil oleogels is extensively studied at microscopic and macroscopic levels. The thermal and mechanical stability of the oleogels is improved when the proportion of the palmitic acid content is increased. However, under stress, the fat crystal network junction zones of the oleogels with higher proportions of palmitic acid undergo disruption. The changes in the properties of the oleogels are due to the alteration in the molecular packing, crystallite size, and lattice strain of the fat crystal network. The alteration in the properties is governed by the changes in the extent of inter‐ and intramolecular hydrogen bonding within the components of the oleogels. The oleogels can demonstrate the ability to deliver the drug, voriconazole, across the corneal tissue. Further, the prepared oleogels are biocompatible to murine fibroblast cells and do not elicit adverse reactions when instilled within the ocular sac of rabbits. The results suggest that the oleogels can be tried as ocular delivery vehicles. Practical Applications: The delivery of drug into the internal structure of the eye is a great challenge for the ophthalmologists. Usually no more than 1% of the drug can be delivered through conventional techniques. Various researchers have proposed the use of lipid‐based ocular drug delivery systems. Some of them include solid liquid nanoparticles, emulsions, and liposomes. However, the preparation of these formulations requires a tedious process. Keeping this in mind, it is proposed to synthesize oleogel as probable ocular drug delivery system.

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“…Liu and coworkers developed an amphiphilic chitosan colloid hydrogel as a shear‐reversible, injectable drug platform for improved glaucoma treatment through a subconjunctival injection . Hoare and coworkers reported a shear‐responsive hydrogel based on hydrophobically modified poly(vinyl pyrrolidone) (PVP) for ophthalmic applications . The viscosity and magnitude of shear thinning of PVP hydrogel can be tuned by controlling the molecular weight of the polymer backbone and/or the length of the hydrophobe grafted to the polymer, with shorter backbone polymers resulting in more shear thinning formulations and longer grafts resulting in continual stiffening of the hydrogel for up to 3 weeks.…”

Section: Ophthalmic Hydrogel Systemmentioning

confidence: 99%

Stimulus‐Responsive Hydrogel for Ophthalmic Drug Delivery

Lin

Lei

Shi

et al. 2019

Macromolecular Bioscience

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Blindness and vision impairment are major global health problems. Effective ophthalmic drug delivery poses a significant challenge because of protective physiological barriers and various biological clearance mechanisms that result in extremely low ocular bioavailability. Over the past several decades, several safe and effective ophthalmic drug delivery approaches have been promoted to combat these problems and to improve ocular bioavailability. Among these approaches, the stimulus‐responsive hydrogel for topical drug delivery has gained increasing attention because of its prolonged drug retention at the local site and enhanced ocular bioavailability. This review summarizes and presents recent advances and perspectives of a stimulus‐responsive hydrogel for ophthalmic drug delivery.

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Hydrophobically-modified poly(vinyl pyrrolidone) as a physically-associative, shear-responsive ophthalmic hydrogel

Cited by 26 publications

References 48 publications

Hydrophobic coagulation of alumina slurries

Hydrophobic coagulation of alumina slurries

Oleogels Based on Palmitic Acid and Safflower Oil: Novel Formulations for Ocular Drug Delivery of Voriconazole

Stimulus‐Responsive Hydrogel for Ophthalmic Drug Delivery

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