Purification of protein therapeutics via high-affinity supramolecular host-guest interactions.

Efficient purification is crucial to providing large quantities of recombinant therapeutic proteins, such as monoclonal antibodies and cytokines. However, affinity techniques for manufacturing protein therapeutics that use biomolecule-conjugated agarose beads that harness specific biomolecular interactions suffer from issues related to protein denaturation, contamination and the need to maintain biomolecule-specific conditions for efficient protein capture. Here, we report a versatile and scalable method for the purification of recombinant protein therapeutics. The method exploits the high-affinity and controllable host-guest interactions between cucurbit[7]uril (CB[7]) and selected guests such as adamantylammonium. We show that the Herceptin (the brand name of trastuzumab, a monoclonal antibody drug used to treat breast cancer) and the much smaller cytokine interferon α-2a can be purified by site-specifically tagging them with adamantylammonium using the enzyme sortase A, followed by high-affinity binding with CB[7]-conjugated agarose beads and the recovery of the protein using a guest with a stronger affinity for CB[7]. The thermal and chemical stability of CB[7] beads and their scalability, recyclability and low cost may also make them advantageous for the manufacturing of biosimilars.

Supra-blot: an accurate and reliable assay for detecting target proteins with a synthetic host molecule-enzyme hybrid.

In accordance with the rapid increase in demand for selective and spatial chemical tagging, and accurate detection of proteins of interest, we develop a sensitive protein detection method, termed "Supra-blot" capitalizing on high-affinity host-guest interaction between cucurbit[7]uril (CB[7]) and adamantylammonium (AdA). The method can directly detect chemically tagged proteins without false-positive signals caused by endogenous biomolecules. Not only a single specific protein, but also spatially localized proteins in cells were labeled with AdA, and selectively detected by a host molecule-enzyme hybrid, CB[7]-conjugated horseradish peroxidase (CB[7]-HRP) generating amplified chemiluminescence signals. This study shows the great potential of Supra-blot for accurate and reliable detection of proteins of interest in cells.

Superacid-Mediated Functionalization of Hydroxylated Cucurbit[n]urils.

Herein we report a facile transformation of hydroxylated cucurbit[n]uril (CB[n], n = 6 and 7) to other functionality-conjugated CB[n]s by nucleophilic substitution of the hydroxyl group with a wide range of nitriles and alcohols. The reaction proceeds efficiently via generation of a superelectrophilic carbocation on the CB framework from hydroxylated CB[n]s under superacidic conditions. One of the resulting CB[n] derivatives with reactive functionality, monocarboxylated CB[7], is efficiently conjugated to an enzyme (horseradish peroxidase, HRP) by amide coupling. This provides a CB[7]-conjugated functional biomaterial (CB[7]-HRP) that selectively detects proteins labeled with a guest, adamantylammonium (AdA), based on bioorthogonal high-affinity host-guest interactions between CB[7] and AdA. We demonstrated the potential of overcoming the limitations in preparing reactive functional CB[n] derivatives, enabling the exploration of novel bioapplications of CB[n]-based host-guest chemistry with new CB[n]-conjugated functional materials.

Self-assembled adhesive biomaterials formed by a genetically designed fusion protein.

Here we report a recombinant protein (MS) obtained by genetic fusion of a mussel foot protein (Mfp3) motif into a silk spidroin (MaSp1). The MS not only self-assembled into a supramolecular fibre, as does the parent MaSp1, but also showed enhanced adhesiveness resulting from the DOPA-containing Mfp3 portion. The successful incorporation of the wet adhesiveness of Mfp3 into the well-structured assembly of MaSp1 may provide a new insight for the genetic design of underwater adhesive recombinant proteins by utilizing the structural features of a spidroin protein.

High-power lithium-ion capacitor using LiMnBO3 -nanobead anode and polyaniline-nanofiber cathode with excellent cycle life.

LiMnBO3 nanobeads (LMB-NB) with uniform size and distribution were synthesized using a urea-assisted microwave/solvothermal method. The potential application of LMB-NBs as an anode for a lithium-ion hybrid capacitor (Li-AHC) was tested with a polyaniline-nanofiber (PANI-NF) cathode in a nonaqueous LiPF6 (1 M)-ethylene carbonate/dimethyl carbonate electrolyte. Cyclic voltammetry (CV) and charge-discharge (C/DC) studies revealed that the PANI-NF/LMB-NB cell showed an exceptional capacitance behavior between 0-3 V along with a prolonged cycle life. A discharge capacitance of about 125 F g(-1) , and energy and power densities of about 42 Wh kg(-1) and 1500 W kg(-1) , respectively, could be obtained at a current density of 1 A g(-1) ; those Li-AHC values are higher relative to cells containing various lithium intercalation materials in nonaqueous electrolytes. In addition, the PANI-NF/LMB-NB cell also had an outstanding rate performance with a capacitance of 54 F g(-1) and a power density of 3250 W kg(-1) at a current density of 2.25 A g(-1) and maintained 94% of its initial value after 30000 cycles. This improved capacitive performance with an excellent electrochemical stability could be the result of the morphological features and inherent conductive nature of the electroactive species.