Living Bacteria–Nanoparticle Hybrids Mediated through Surface-Displayed Peptides

Abstract

In this study, we investigated the preparation of living bacteria-nanoparticle hybrids mediated by surface-displayed peptides. The assembly of metallic nanoparticles on living bacteria has been achieved under mild conditions utilizing metal-peptide interactions, whereas the viability of the bacterial cells was greatly preserved. Escherichia coli was engineered with inducible gene circuits to control the display of peptides with desired sequences. Several designed peptide sequences as well as known gold-binding peptides were expressed on the cell surface using enhanced circularly permuted outer membrane protein X (eCPX) scaffolds. Driven by metal-peptide affinity, "biofriendly" citrate-stabilized gold nanoparticles were self-assembled onto the surface of bacteria with displayed peptides, which required overcoming the repulsive force between negatively charged nanoparticles and negatively charged cells. The bacteria/Au nanoparticle hybrids were highly viable and maintained the ability to grow and divide, which is a crucial step toward the creation of living material systems. Further activity and preservation of the bacterial hybrid assembly was demonstrated. The method described herein enables the conjugation of bacterial surfaces with diverse metal-rich nanoparticles in an inducible, and therefore easily controlled, manner. The expressed peptide sequences can be easily modified to alter the binding affinity and specificity for a wide variety of materials to form on-demand, high-density living biohybrids.

Discovery of Targeted Material Binding Microorganisms Using a Centrifugal Microfluidic Platform

“…Another reason to first utilize gold as a target substrate is due to the availability of positive control microbial strains, since there are several previously identified microbes that show high selective affinity against gold. [ 16,41 ] In order to achieve successful biopanning of the eCPX 3.0 library against gold or ITO, the optimum shear stress condition was first investigated with four E. coli strains known to have different affinities toward gold. This condition was then used to isolate cells with novel peptide sequences that selectively bind to gold or to ITO from the bacterial display library.…”

Improved Microbial Fuel Cell Performance by Engineering E. coli for Enhanced Affinity to Gold

“…Gold-binding peptides were inserted at both termini. On the N terminal side, a variety of gold-binding peptides known from the literature [38][39][40] and listed in Figure 1C were incorporated after a CTSGQ linker, while on the C terminal side, the P2X peptide, a YPet-Mona binding motif with some affinity to gold, was used [17]. Variants of the eCPX scaffold are, therefore, available with and without each of N-terminal cysteine, additional N-terminal gold-binding sequences and C-terminal P2X.…”

“…For inducible bacterial peptide display by eCPX, MC1061 E. coli containing pDSJR plasmid (Cm R ) with P2X removed [17] (referred to as "no cys no P2X") or pB33-nl3 (Cm R ) with or without P2X [11,44] (referred to as "cys P2X" and "cys no P2X", respectively) were used. Both are pBad33-eCPX variants, with the pB33-nl3 having CTSGQ leading peptide at the N-terminal while pDSJR instead has GTSGQ; all peptides were inserted just after the N terminal of the pB33-nl3 with P2X ("cys P2X") and are therefore preceded by CTSGQ.…”

“…They can also be engineered into microorganisms, including outer membrane proteins, fimbriae and other structures to change the adhesion behavior of microorganisms. By incorporating material binding peptides, it has been possible to use living cells to template them on surfaces [11], to bind nanoparticles [17] and to create biohybrid devices [1].…”

Photosynthetic Tumor Oxygenation by Photosensitizer‐Containing Cyanobacteria for Enhanced Photodynamic Therapy

“…[2] Although these methodologies resulted in unstable therapeutic outcomes,t hese pioneering trials have ushered an ew era for microorganism-based tumor therapy.U pon elaborate fabrication and biological manipulation, various types of bacterial cells have been engineered to serve as delivery vectors for chemotherapeutics, [3] plasmids, [4] proteins [5] as well as other composite nanoplatforms for tumor therapies. [6] Such modifications may endow bacterial cells with diverse therapeutic functions,i ncluding Fenton nanocatalytic therapeutics, [7] photothermal eradication, [8] and biotherapy, [9] contributing to the next generation of tumor nanomedicine,t ermed microbiotic nanomedicine.…”