Democratic presidential frontrunner Hillary Clinton said in an interview aired Wednesday night that special interest groups cannot buy her to gain access and influence as she continues to face scrutiny for taking large sums of money in speaking fees from the financial industry in recent years.

Speaking over the phone with MSNBC's Chris Matthews, Clinton was asked how she will respond to impending attack ads from her main primary challenger, Sen. Bernie Sanders (I, Vt.), who is expected to target her ties to Wall Street.

"As anybody who knows me knows, you can't buy me," Clinton said in response, defending her commitment to regulate financial firms and weaken Wall Street's influence.

"I've been standing up and fighting and getting knocked around for years trying to get things done that I think would improve peoples' lives, and I'm not going to stop," Clinton added. "And that includes anybody trying to, you know, mess with our financial system."

Clinton described Sanders’ attacks as "disappointing" and a "low blow," saying the Senator from Vermont is becoming "increasingly personal with his attacks" and breaking his pledge to not conduct a negative campaign.

The Democratic frontrunner has come under fire in recent weeks for having connections to Wall Street and receiving significant amounts of money from the financial industry during a primary that has largely focused on targeting Wall Street firms to address income inequality.

A New York Times report from last week detailed how Bill and Hillary Clinton have taken in more than $125,000,000 in speaking fees since they left the White House, much of which came from Wall Street-linked financial firms.

Just under a quarter of the money has come in the last two years.

Nicholas Confessore, one of the authors of the article, told MSNBC last week that the amount of money the former first couple has amassed from speaking engagements is "almost obscene."

Clinton made on average about $250,000 per speech, including $675,000 from Wall Street giant Goldman Sachs for three speeches.

Sanders, a self-declared socialist, has attacked Clinton for being too close to Wall Street and being aligned with corporate interests. He has promised to break up America's largest banks and restore the Glass-Steagall barrier between investment and commercial banking.

Sanders has called the American economy a rigged system that only benefits the wealthy while oppressing working and middle class Americans.

Clinton has made similar comments on the campaign trail and said she will do more to mitigate the power of Wall Street and the broader financial industry through stricter regulation, but Sanders has called her hypocritical because of the money she has taken from Wall Street.

Sanders is planning a new blitz of attack ads targeting Clinton in the final days before the Iowa caucuses are held on Feb. 1. Recent polls show Clinton and Sanders are neck-and-neck in Iowa, while Sanders holds a large lead in New Hampshire, the next state to vote in the primary.