Application Guide: Virus Characterization

Spectradyne’s ARC™ Particle Analyzer

Published:
Revision: V3

Overview

Spectradyne’s ARC™ particle analyzer is rapidly being adopted for virus quantification in research and GMP lab environments. It delivers fast viral titer measurements as well as single-particle molecular analysis using fluorescence for in-depth characterization.

The ARC enables accurate measurement of virus size and concentration, quantitative payload identification, and surface marker analysis directly in complex media without isolation or sample cleanup.

How the ARC Particle Analyzer Works

  1. Microfluidic Resistive Pulse Sensing (MRPS) directly measures single-particle size and concentration. MRPS is a non-optical electrical technique that is orthogonal to DLS, NTA, and flow cytometry.
  2. Single-particle fluorescence directly quantifies payload and surface ligands. Color multiplexing enables simultaneous measurements of encapsulated payloads, co-encapsulation, and targeting ligands.

Gold-Standard Accuracy for Size and Concentration

Comparison of particle size and concentration measurements using MRPS and Cryo-TEM
Figure 1. Comparison of MRPS and Cryo-TEM measurements for an mRNA-loaded LNP formulation. The ARC measured 1906 particles in approximately two minutes, yielding a concentration of 4.2 × 10¹² particles/mL.

Direct comparison of MRPS and Cryo-TEM shows remarkable agreement across the full measurement range, validating the ARC’s accuracy for virus characterization.

Rapid Viral Titer in Complex Media

The ARC delivers simultaneous measurements of size, concentration, and fluorescence intensity. Up to three optical detection bands enable quantitative analysis of surface ligands and encapsulated payloads using standard fluorescence units.

Particle size distributions of adenovirus and extracellular vesicles measured by MRPS
Figure 2. Particle size distributions for adenovirus, extracellular vesicles (EVs), and their mixture. Fluorescence gating enables direct quantification of adenovirus concentration in complex samples.

Quantifying RNA-Loaded Lentivirus

RNA-loaded lentivirus can be quantified directly using SYBR Gold fluorescence staining. Fluorescence-positive particles identify the loaded virion subpopulation within complex samples.

Size distribution and fluorescence scatter plot identifying RNA-loaded lentivirus
Figure 5. Size distribution and fluorescence analysis of RNA-loaded lentivirus, revealing the full virion subpopulation using F-MRPS.

Compatibility with a Variety of Virus Samples