Serum albumin–protamine conjugate for biocompatible platform for targeted delivery of therapeutic macromolecules

Abstract

A well-defined, one-to-one conjugate between human serum albumin (HSA) and protamine was synthesized and characterized as a biocompatible carrier for macromolecules. In circulation, the conjugate will camouflage drug molecules upon complex formation, while liberating free drug at the desired location using a triggering mechanism. The N-terminus of protamine was thiolated and conjugated with the unpaired Cysteine-34 of HSA, and was purified by ion-exchange chromatography. The molecular weight of the conjugate was 70.8 kDa, confirming one-to-one conjugation between HSA (66.6 KDa) and protamine (4200 Da). Superimposed fluorescence spectra of native HSA and HSA-protamine conjugate indicated no conformational change around the Trp-214. The conjugate had marked reduction in hemolytic and cytotoxic properties compared to protamine. When therapeutic potential was tested using tissue plasminogen activator as a model drug, HSA-protamine conjugate suppressed the enzymatic activity by 65%, which was fully recovered by a triggering agent, heparin. The construct showed binding characteristics with activated platelets upon conjugation with a targeting peptide, demonstrating flexibility to introduce suitable homing moiety on the surface. The camouflaged construct retained triggered release property in human plasma condition. Overall, the conjugate has a good potential to serve as a biocompatible platform for macromolecular drugs.

Radionuclide I-131 Labeled Albumin-Paclitaxel Nanoparticles for Synergistic Combined Chemo-radioisotope Therapy of Cancer

“…Human serum albumin (HSA), an abundant serum protein with inherent biocompatibility, has been demonstrated to be an ideal drug carrier 11 , 12 . As a compelling case, nanoparticles of HSA bound with paclitaxel (PTX), a potent anti-cancer drug, has been approved by US Food and Drug Administration (FDA) for cancer treatment under the trade name of Abraxane ® 13 , 14 .…”

Thiol–ene Click Hydrogels for Therapeutic Delivery

“…Uncontrolled reactions can contribute to loss of bioactivity and degradation of therapeutic peptides and proteins and hence generally are undesirable. Even so, this approach has been utilized to conjugate biologics to polymeric drug carriers. , …”

“…Even so, this approach has been utilized to conjugate biologics to polymeric drug carriers. 69,70 3.3. Types of Alkenes Used for Thiol−ene Hydrogel Formation.…”

Engineering of plasminogen activators for targeting to thrombus and heightening thrombolytic efficacy

“…We recently proposed a heparin-triggered approach in which t-PA is camouflaged by human serum albumin via electrostatic interactions [76]. Albumin was first conjugated to protamine; the positive charge of the resulting conjugate interacted with electronegative t-PA that was functionalized with 7-mers of glutamate.…”

“…The electrostatic interactions between polyglutamate and protamine give rise to the camouflaged t‐ PA . (C) Camouflaged t‐ PA in the systemic circulation: (i) albumin molecules surrounding the t‐ PA prevent it from binding to macromolecules in the plasma; (ii) accumulation of the complex on activated platelets via targeting peptide–glycoprotein II b– III a; (iii) administration of heparin after accumulation of the complex at the thrombus site; (iv) triggered release of t‐ PA for local plasminogen activation and fibrinolysis . SPDP (Succinimidyl‐3‐(2‐pyridyldithio)‐propionate).…”