Controlled release of lipase from Candida rugosa loaded into hydrogels of N-isopropylacrylamide and itaconic acid

Achievements and Trends in Biocatalytic Synthesis of Specialty Polymers from Biomass-Derived Monomers Using Lipases

New technologies for the conversion of biomass into high-value chemicals, including polymers and plastics, is a must and a challenge. The development of green processes in the last decade involved a continuous increase of the interest towards the synthesis of polymers using in vitro biocatalysis. Among the remarkable diversity of new bio-based polymeric products meeting the criteria of sustainability, biocompatibility, and eco-friendliness, a wide range of polyesters with shorter chain length were obtained and characterized, targeting biomedical and cosmetic applications. In this review, selected examples of such specialty polymers are presented, highlighting the recent developments concerning the use of lipases, mostly in immobilized form, for the green synthesis of ε-caprolactone co-polymers, polyesters with itaconate or furan units, estolides, and polyesteramides. The significant process parameters influencing the average molecular weights and other characteristics are discussed, revealing the advantages and limitations of biocatalytic processes for the synthesis of these bio-based polymers.

An update on smart biocatalysts for industrial and biomedical applications

Recently, smart biocatalysts, where enzymes are conjugated to stimuli-responsive (smart) polymers, have gained significant attention. Based on the presence or absence of external stimuli, the polymer attached to the enzyme changes its conformation to protect the enzyme from the external environment and regulate the enzyme activity, thus acting as a molecular switch. Owing to this behaviour, smart biocatalysts can be separated easily from a reaction mixture and re-used several times. Several such smart polymer-based biocatalysts have been developed for industrial and biomedical applications. In addition, they have been used in biosensors, biometrics and nano-electronic devices. This review article covers recent advances in developing different kinds of stimuli-responsive enzyme bioconjugates, including conjugation strategies, and their applications.

Investigation on pH-switchable (itaconic acid/ethylene glycol/acrylic acid) based polymeric biocompatible hydrogel

A new variety of pH-sensitive polymeric hydrogels (IAE) have been developed and evaluated as biocompatible hydrogels using synergetic combinations of itaconic acid (IA), acrylic acid (AA), and ethylene glycol (EG) in water medium by free radical polymerization.

Long-term delivery of protein therapeutics

INTRODUCTION

Proteins are effective biotherapeutics with applications in diverse ailments. Despite being specific and potent, their full clinical potential has not yet been realized. This can be attributed to short half-lives, complex structures, poor in vivo stability, low permeability, frequent parenteral administrations and poor adherence to treatment in chronic diseases. A sustained release system, providing controlled release of proteins, may overcome many of these limitations.

AREAS COVERED

This review focuses on recent development in approaches, especially polymer-based formulations, which can provide therapeutic levels of proteins over extended periods. Advances in particulate, gel-based formulations and novel approaches for extended protein delivery are discussed. Emphasis is placed on dosage form, method of preparation, mechanism of release and stability of biotherapeutics.

EXPERT OPINION

Substantial advancements have been made in the field of extended protein delivery via various polymer-based formulations over last decade despite the unique delivery-related challenges posed by protein biologics. A number of injectable sustained-release formulations have reached market. However, therapeutic application of proteins is still hampered by delivery-related issues. A large number of protein molecules are under clinical trials, and hence, there is an urgent need to develop new methods to deliver these highly potent biologics.

Stimuli-sensitive hydrogel based on N-isopropylacrylamide and itaconic acid for entrapment and controlled release of Candida rugosa lipase under mild conditions

Stimuli responsive pH- and temperature-sensitive hydrogel drug delivery systems, as those based on N-isopropylacrylamide (NiPAAm) and itaconic acid (IA), have been attracting much of the attention of the scientific community nowadays, especially in the field of drug release. By adjusting comonomer composition, the matrix is enabled to protect the incorporated protein in the highly acidic environment of upper gastrointestinal tract and deliver it in the neutral or slightly basic region of the lower intestine. The protein/poly(NiPAAm-co-IA) hydrogels were synthetized by free radical crosslinking copolymerization and were characterized concerning their swelling capability, mechanical properties, and morphology. The pore structure and sizes up to 1.90 nm allowed good entrapment of lipase molecules. Model protein, lipase from Candida rugosa, was entrapped within hydrogels upon mild conditions that provided its protection from harmful environmental influences. The efficiency of the lipase entrapment reached 96.7%, and was dependent on the initial concentration of lipase solution. The swelling of the obtained hydrogels in simulated pH and temperature of gastrointestinal tract, the lipase entrapment efficiency, and its release profiles from hydrogels were investigated as well.

Assessment of the drug loading, in vitro and in vivo release behavior of novel pH-sensitive hydrogel

CONTEXT

As a glucocorticoid drug, dexamethasone has good therapeutic effects for ulcerative colitis. pH-sensitive hydrogels could make conventional changes of volume in response with different pH values. Meanwhile, they could load drugs depending on its internal three-dimensional network structure.

OBJECTIVE

Appropriate methods were used to improve the drug-loading capacity of hydrogel and exploring the colon-targeting character of dexamethasone hydrogel.

MATERIALS AND METHODS

Different solvents (ethanol and 1,2-propanediol) were employed to dissolve dexamethasone as well as hydrogel monomer materials (poly(ethylene glycol) methyl ether (MPEG)-poly(lactide acid)-acryloyl chloride macromonomer, itaconic acid (IA) and MPEG-methacrylate), then mixing them together to prepare hydrogel through the heat-initiated free radical polymerization method. Differential scanning calorimetry and X-ray diffraction methods were used to verify whether dexamethasone was loaded into hydrogels. In vitro drug release behavior and in vivo pharmacokinetic study were also investigated in detail.

RESULTS

Dexamethasone was successfully loaded into hydrogel, and its loading capacity was improved (5 mg/g). Both the in vitro release study and the in vivo pharmacokinetic study showed the good colon-targeting character of the pH-sensitive P(LE-IA-MEG) hydrogel (T max = 1.0 h, C max = 2.16 µg/ml of dexamethasone; T max = 3.9 h, C max = 0.43 µg/ml of dexamethasone hydrogel).

DISCUSSION

Dexamethasone could be targeted to the colon site by P(LE-IA-MEG) hydrogel, thereby improving its therapeutic effect and reduce its side effects.

CONCLUSION

P(LE-IA-MEG) hydrogel might have great potential application in colon-targeted drug delivery systems.

Development of poly(N-isopropylacrylamide)/alginate copolymer hydrogel-grafted fabrics embedding of berberine nanosuspension for the infected wound treatment

In the present study, a novel hydrogel-grafted fabrics embedding of berberine nanosuspension was developed for the treatment of infected wound. Hydrogel-grafted fabric was prepared by graft copolymerization of N-isopropylacrylamide and alginate using ceric ammonium nitrate as initiator. Berberine nanosuspension was prepared and embedded in the hydrogel-grafted fabrics to achieve sustained drug release. The prepared hydrogel-grafted fabrics embedding of berberine nanosuspension was characterized by FT-IR spectroscopy, scanning electron microscopy, and swelling degree studies. Fourier transform infrared spectroscopy revealed that berberine was embedded into the matrix of hydrogel-grafted fabrics, rather than on the surface. Scanning electron microscopy showed that a thin hydrogel layer was formed on the surface of nonwoven fibers. The swelling study showed that hydrogel-grafted fabric had water absorbing characteristic with reversible temperature sensitivity. The drug release study demonstrated that hydrogel-grafted fabrics can be used as a sustained drug delivery system of hydrophobic compounds. The berberine nanosuspension embedded hydrogel-grafted fabric was further investigated in an animal infected wound model and was found to be a very promising wound healing dressing for the treatment and healing of infected wounds.